Patent Publication Number: US-2023133233-A1

Title: Endoscope treatment tool

Description:
RELATED APPLICATION DATA 
     This application is based on and claims priority under 35 U.S.C. § 119 to U.S. Provisional Application Nos. 63/273,174 and 63/273,179, each of which was filed on Oct. 29, 2021. The entire contents of each of these applications are incorporated herein by reference. 
    
    
     FIELD OF THE DISCLOSURE 
     The present disclosure relates to an endoscope treatment tool. 
     BACKGROUND 
     An endoscope treatment tool has been known conventionally, the treatment tool including an insertion portion inserted into a body cavity via an endoscope and being for incision of a site (hereinafter, referred to as a target site) to be treated in body tissue by means of high frequency electric current (see, for example, Specification of Chinese Patent Application Publication No. 108272503). 
     The insertion portion of the endoscope treatment tool described in Specification of Chinese Patent Application Publication No. 108272503 includes: a sheath having a first hole at a distal end of the sheath, the first hole connecting the interior and the exterior to each other; and an incision portion that protrudes outside the sheath from the first hole and makes an incision in the target site by passage of the high frequency electric current. This incision portion has a second hole provided therein, the second hole penetrating the incision portion from near a proximal end of the incision portion to a distal end of the incision portion. This endoscope treatment tool is configured to be switched between: a first mode where liquid is passed to flow into the body cavity from a clearance between an inner surface of the first hole and an outer surface of the incision portion; and a second mode where the liquid is passed to flow into the body cavity from a second hole. 
     SUMMARY 
     In some embodiments, an endoscope treatment tool includes a sheath and an incision device. The sheath includes a distal end portion having a first channel. The first channel extends internal to the distal end portion between a distal opening at a distal end surface of the distal end portion and a proximal opening at a main flow chamber. The incision device is inserted in the first channel and includes a second channel extending between a distal end of the incision device and a proximal end of the incision device. The endoscope treatment tool is switchable between a first mode and a second mode. The endoscope treatment tool is in the first mode when the incision device is in a first position and the endoscope treatment tool is in the second mode when the incision device is in a second position. In the first mode, a first path for fluid is formed between the main flow chamber and the first channel. In the second mode, a second path for fluid is formed between the main flow chamber and the second channel. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a diagram illustrating an endoscope system according to a first embodiment. 
         FIG.  2    is a diagram illustrating a configuration of a treatment tool insertion portion. 
         FIG.  3    is a diagram illustrating the configuration of the treatment tool insertion portion. 
         FIG.  4    is a diagram illustrating the configuration of the treatment tool insertion portion. 
         FIG.  5    is a diagram illustrating the configuration of the treatment tool insertion portion. 
         FIG.  6    is a diagram illustrating operation of an endoscope treatment tool. 
         FIG.  7    is a diagram illustrating operation of the endoscope treatment tool. 
         FIG.  8    is a diagram illustrating operation of the endoscope treatment tool. 
         FIG.  9    is a diagram illustrating operation of the endoscope treatment tool. 
         FIG.  10    is a diagram illustrating a configuration of a treatment tool insertion portion according to a second embodiment. 
         FIG.  11    is a diagram illustrating the configuration of the treatment tool insertion portion according to the second embodiment. 
         FIG.  12    is a diagram illustrating operation of an endoscope treatment tool. 
         FIG.  13    is a diagram illustrating operation of the endoscope treatment tool. 
         FIG.  14    is a diagram illustrating a modified example of the second embodiment. 
         FIG.  15    is a diagram illustrating a configuration of a treatment tool insertion portion according to a third embodiment. 
         FIG.  16    is a diagram illustrating the configuration of the treatment tool insertion portion according to the third embodiment. 
         FIG.  17    is a diagram illustrating operation of an endoscope treatment tool. 
         FIG.  18    is a diagram illustrating operation of the endoscope treatment tool. 
         FIG.  19    is a diagram illustrating a configuration of a treatment tool insertion portion according to a fourth embodiment. 
         FIG.  20    is a diagram illustrating the configuration of the treatment tool insertion portion according to the fourth embodiment. 
         FIG.  21    is a diagram illustrating the configuration of the treatment tool insertion portion according to the fourth embodiment. 
         FIG.  22    is a diagram illustrating the configuration of the treatment tool insertion portion according to the fourth embodiment. 
         FIG.  23    is a diagram illustrating the configuration of the treatment tool insertion portion according to the fourth embodiment. 
         FIG.  24    is a diagram illustrating operation of an endoscope treatment tool. 
         FIG.  25    is a diagram illustrating operation of the endoscope treatment tool. 
         FIG.  26    is a diagram illustrating a configuration of a treatment tool insertion portion according to a fifth embodiment. 
         FIG.  27    is a diagram illustrating the configuration of the treatment tool insertion portion according to the fifth embodiment. 
         FIG.  28    is a diagram illustrating the configuration of the treatment tool insertion portion according to the fifth embodiment. 
         FIG.  29    is a diagram illustrating the configuration of the treatment tool insertion portion according to the fifth embodiment. 
         FIG.  30    is a diagram illustrating the configuration of the treatment tool insertion portion according to the fifth embodiment. 
         FIG.  31    is a diagram illustrating the configuration of the treatment tool insertion portion according to the fifth embodiment. 
         FIG.  32    is a diagram illustrating operation of an endoscope treatment tool. 
         FIG.  33    is a diagram illustrating operation of the endoscope treatment tool. 
         FIG.  34    is a diagram illustrating a configuration of a treatment tool insertion portion according to a sixth embodiment. 
         FIG.  35    is a diagram illustrating the configuration of the treatment tool insertion portion according to the sixth embodiment. 
         FIG.  36    is a diagram illustrating operation of an endoscope treatment tool. 
         FIG.  37    is a diagram illustrating operation of the endoscope treatment tool. 
         FIG.  38    is a diagram illustrating a configuration of a treatment tool insertion portion according to a seventh embodiment. 
         FIG.  39    is a diagram illustrating the configuration of the treatment tool insertion portion according to the seventh embodiment. 
         FIG.  40    is a diagram illustrating operation of an endoscope treatment tool. 
         FIG.  41    is a diagram illustrating operation of the endoscope treatment tool. 
         FIG.  42    is a diagram illustrating a configuration of a treatment tool insertion portion according to an eighth embodiment. 
         FIG.  43    is a diagram illustrating the configuration of the treatment tool insertion portion according to the eighth embodiment. 
         FIG.  44    is a diagram illustrating operation of an endoscope treatment tool. 
         FIG.  45    is a diagram illustrating operation of the endoscope treatment tool. 
         FIG.  46 A  is a diagram illustrating an example of a shape of a projecting portion. 
         FIG.  46 B  is a diagram illustrating an example of the shape of the projecting portion. 
     
    
    
     DETAILED DESCRIPTION 
     Modes for implementing the disclosure (hereinafter, embodiments) will be described hereinafter while reference is made to the drawings. The disclosure is not limited by the embodiments described hereinafter. Furthermore, any portions that are the same will be assigned with the same reference sign, throughout the drawings. 
     First Embodiment 
     Configuration of Endoscope System 
       FIG.  1    is a diagram illustrating an endoscope system  1  according to a first embodiment. 
     The endoscope system  1  is a system that is used in the medical field and that is for observation of the interior of a body cavity and for application of high frequency energy to a site to be treated (hereinafter, referred to as a target site) in body tissue in the body cavity and treatment of the target site thereby. The treatment that is able to be executed by means of the endoscope system  1  according to the first embodiment is treatment, such as coagulation (sealing) of the target site, or incision of the target site. As illustrated in  FIG.  1   , this endoscope system  1  includes an endoscope  2 , a display device  3 , a light source device  4 , a control device  5 , and an endoscope treatment tool  6 . 
     Part of the endoscope  2  is inserted into a body cavity, and the endoscope  2  captures a subject image reflected from the interior of the body cavity and outputs an image signal generated by the capturing. As illustrated in  FIG.  1   , this endoscope  2  includes an endoscope insertion unit  21 , an endoscope operating unit  22 , a universal cord  23 , and a connector unit  24 . 
     At least part of the endoscope insertion unit  21  has flexibility and the endoscope insertion unit  21  is a portion to be inserted into the body cavity. This endoscope insertion unit  21  includes, as illustrated in  FIG.  1   , a distal end unit  211 , a bending portion  212 , and a flexible tube  213 . 
     The distal end unit  211  is provided at a distal end of the endoscope insertion unit  21 . This distal end unit  211  has, provided therein, an illumination optical system, an imaging optical system, and an imaging unit, although specific illustration thereof has been omitted. 
     The illumination optical system faces one end of a light guide (not illustrated in the drawings) laid in the endoscope insertion unit  21 , and light that has been transmitted through the light guide is emitted from the distal end of the endoscope insertion unit  21  into a body cavity. 
     The imaging optical system receives light (a subject image) that has been emitted into the body cavity from the illumination optical system and reflected from the interior of the body cavity, and forms the subject image on an imaging surface of an imaging element included in the imaging unit. 
     The imaging unit includes the imaging element, such as a charge coupled device (CCD) or a complementary metal oxide semiconductor (CMOS), captures the subject image formed by the imaging optical system, and outputs an image signal generated by the capturing. 
     The bending portion  212  is connected to the distal end unit  211  near a proximal end of the distal end unit  211  (near the endoscope operating unit  22 ). This bending portion  212  has a configuration with plural bending pieces connected to each other and is bendable, although specific illustration thereof has been omitted. 
     The flexible tube  213  is connected to the bending portion  212  near a proximal end (near the endoscope operating unit  22 ) of the bending portion  212 , is elongated, and has flexibility. 
     The endoscope operating unit  22  is connected to a proximal end portion of the endoscope insertion unit  21 . The endoscope operating unit  22  receives various operations for the endoscope  2 . This endoscope operating unit  22  has, as illustrated in  FIG.  1   , provided therein, plural operating members  221 , a bending knob  222 , and an insertion opening  223 . 
     The plural operating members  221  include, for example, buttons that receive various operations. 
     The bending knob  222  is configured to be rotatable according to a user operation. By rotating, the bending knob  222  causes a bending mechanism (not illustrated in the drawings) to operate, the bending mechanism being, for example, a wire provided in the endoscope insertion unit  21  and made of metal or resin. The bending portion  212  is thereby bent. 
     The insertion opening  223  is an insertion opening that communicates with a duct (not illustrated in the drawings) extending from the distal end to near a proximal end (near the endoscope operating unit  22 ) of the endoscope insertion unit  21 , the insertion opening being for insertion of, for example, a treatment tool insertion portion  7  of the endoscope treatment tool  6 , into the duct, from the outside. 
     The universal cord  23  is a cord that extends from the endoscope operating unit  22 , in a direction different from an extending direction of the endoscope insertion unit  21  and has, provided therein, for example, the light guide described above and a signal line for transmission of the image signal described above. 
     The connector unit  24  is provided at an end portion of the universal cord  23  and is detachably connected to the light source device  4  and the control device  5 . 
     The display device  3  is, for example, a liquid crystal display (LCD) or an electroluminescence (EL) display, and displays a predetermined image, under control by the control device  5 . 
     The light source device  4  emits illumination light. The illumination light emitted from the light source device  4  is emitted into a body cavity from the distal end of the endoscope insertion unit  21  after passing through the connector unit  24 , the universal cord  23 , the endoscope operating unit  22 , the light guide laid in the endoscope insertion unit  21 , and the illumination optical system. 
     The control device  5  includes, for example, a central processing unit (CPU) or a field-programmable gate array (FPGA), and integrally controls operation of the display device  3  and the light source device  4 . 
     For example, the control device  5  performs predetermined processing of an image signal input through the signal line mentioned above from the imaging unit described above and generates an endoscopic image. The control device  5  then controls operation of the display device  3  and causes the display device  3  to display the endoscopic image, for example. 
     In this first embodiment, the light source device  4  and the control device  5  are configured to be separately bodied, but may be integrally provided in a single casing. 
     Configuration of Endoscope Treatment Tool 
     The endoscope treatment tool  6  is a treatment tool used in, for example, endoscopic submucosal dissection (ESD). This treatment tool  6  for an endoscope includes, as illustrated in  FIG.  1   , the treatment tool insertion portion  7  and a treatment tool operating unit  8 . 
     As illustrated in  FIG.  1   , the treatment tool insertion portion  7  is a portion that protrudes from the distal end of the endoscope insertion unit  21  by passing through the duct in the endoscope insertion unit  21  from the insertion opening  223  and that is to be inserted into a body cavity, and the treatment tool insertion portion  7  corresponds to an insertion portion. 
     A detailed configuration of the treatment tool insertion portion  7  will be described in a later section, “Configuration of Treatment Tool Insertion Portion”. Furthermore, a “distal end” referred to hereinafter means one end of the treatment tool insertion portion  7 , the one end being in an insertion direction in which the treatment tool insertion portion  7  is inserted, and a “proximal end” referred to hereinafter means the other end of the treatment tool insertion portion  7 , the other end being in a direction opposite to the insertion direction. 
     The treatment tool operating unit  8  is connected to a proximal end portion of the treatment tool insertion portion  7  (a portion near the proximal end of the treatment tool insertion portion  7  with respect to the insertion direction). The treatment tool operating unit  8  receives an operation on the endoscope treatment tool  6 . This treatment tool operating unit  8  includes, as illustrated in  FIG.  1   , an operating unit main body  81  and a slider  82 . 
     The operating unit main body  81  has an elongated shape, and a proximal end portion of a sheath  9  included in the treatment tool insertion portion  7  and described later is fixed to the operating unit main body  81 . Furthermore, a ring  811  is provided at a proximal end portion of the operating unit main body  81 , the ring  811  being for an operator, such as an operating surgeon, to place the operator&#39;s finger, as illustrated in  FIG.  1   . In addition, a water feeding port  812  is provided in the operating unit main body  81 , the water feeding port  812  being where a tube TU is connected to. Saline solution is supplied from a water feeding source  200 , such as a pump, to the water feeding port  812  via the tube TU. 
     This saline solution corresponds to fluid. The fluid is not necessarily saline solution, and any other liquid, or gas, such as air, may be adopted as the fluid. 
     The slider  82  is attached to the operating unit main body  81  so that the slider  82  is movable along a longitudinal direction of the operating unit main body  81  according to an operation performed by an operator, such as an operating surgeon. As illustrated in  FIG.  1   , this slider  82  has a pair of rings  821  for the operator, such as the operating surgeon, to place the operator&#39;s finger/fingers on. Furthermore, a plug  822  where a power source cord CO is connected to is provided in the slider  82 . The plug  822  is electrically connected to a power source  100  via the power source cord CO. 
     Configuration of Treatment Tool Insertion Portion 
       FIG.  2    to  FIG.  5    are diagrams each illustrating a configuration of the treatment tool insertion portion  7 . Specifically,  FIG.  2    is a sectional view of a distal end portion of the treatment tool insertion portion  7 , the sectional view being taken upon a plane including a central axis of the treatment tool insertion portion  7 .  FIG.  3    is a sectional view of the treatment tool insertion portion  7 , the sectional view being taken at a position of a line III-III illustrated in  FIG.  2   .  FIG.  4    is a sectional view of the treatment tool insertion portion  7 , the sectional view being taken at a position of a line IV-IV illustrated in  FIG.  2   .  FIG.  5    is a sectional view of the treatment tool insertion portion  7 , the sectional view being taken at a position of a line V-V illustrated in  FIG.  2   . 
     As illustrated in  FIG.  1    to  FIG.  5   , the treatment tool insertion portion  7  includes the sheath  9 , a wire  10  ( FIG.  2   ), and an incision portion  11  ( FIG.  2   ). The incision portion  11  may correspond to an incision device. 
     The sheath  9  is a portion forming an outer surface of the treatment tool insertion portion  7 . This sheath  9  includes, as illustrated in  FIG.  1    and  FIG.  2   , a sheath main body  91  and a distal end member  92 . 
     The sheath main body  91  is a cylindrical member formed of, for example, a resin material and having insulation and flexibility. A proximal end portion of the sheath main body  91  is fixed to the operating unit main body  81 . The interior of the sheath main body  91  communicates with the water feeding port  812 . 
     The distal end member  92  has a cylindrical shape with a bottom, and closes a distal end portion of the sheath main body  91 , in a posture where a bottom portion  920  thereof is oriented in a distal direction (leftward in  FIG.  2   ). This distal end member  92  may be formed of a member made of ceramic, a resin material, or rubber, for example, and having electric insulation, or may be formed of a member having an insulation coating, for example, such as metal, on a surface thereof. The distal end member  92  may be formed of a single part or may be formed of a combination of plural parts. 
     First and second wall portions  9211  and  9212  are provided on an inner peripheral surface  921  of the distal end member  92 , as illustrated in  FIG.  2    and  FIG.  5   . 
     The first wall portion  9211  is a wall protruding toward a central axis of the distal end member  92  from the inner peripheral surface  921  and extending along the central axis, as illustrated in  FIG.  2    and  FIG.  5   . 
     The second wall portion  9212  is a wall protruding toward the central axis of the distal end member  92  from the inner peripheral surface  921  and extending along the central axis to the bottom portion  920  of the distal end member  92 , as illustrated in  FIG.  2    and  FIG.  5   . Furthermore, as illustrated in  FIG.  2    and  FIG.  5   , a groove portion  9213  extending over the entire length of the second wall portion  9212  is provided in the second wall portion  9212 . 
     The interior of the sheath main body  91  and the interior of the distal end member  92  described above function as a main flow channel M 1  ( FIG.  2   ), the main flow channel M 1  being where saline solution supplied from the water feeding source  200  flows through via the tube TU and the water feeding port  812 . The main flow channel M 1  may correspond to a main flow chamber. 
     Furthermore, a first hole  922  that provides communication between the bottom portion  920  and a distal end of the distal end member  92  is provided in the bottom portion  920  of the distal end member  92 , as illustrated in  FIG.  2    to  FIG.  4   , and this first hole  922  is open in the bottom portion  920  and at the distal end of the distal end member  92 . This bottom portion  920  corresponds to a distal end portion of a sheath. The first hole  922  may correspond to a first channel. 
     The first hole  922  has a circular cross-section and extends linearly along the central axis of the distal end member  92 . The dimension of the inner diameter of the first hole  922  is set smaller than the dimension of the inner diameter of the inner peripheral surface  921 , as illustrated in  FIG.  2   . The first hole  922  may preferably be positioned on the central axis of the distal end member  92 . 
     The wire  10  is formed of an electrically conducting material, such as metal, and is inserted in the sheath  9 . A proximal end portion of the wire  10  is fixed to the slider  82 . That is, according to an operation on the slider  82  by an operator, such as an operating surgeon, the wire  10  advances or retracts in the sheath  9 . Furthermore, the wire  10  is electrically connected to the plug  822 . 
     The incision portion  11  is formed of an electrically conducting material, such as metal, and is fixed to a distal end portion of the wire  10 . Furthermore, the incision portion  11  is inserted in the first hole  922 . That is, together with the wire  10 , the incision portion  11  advances or retracts in the sheath  9  (the first hole  922 ) according to an operation on the slider  82  by an operator, such as an operating surgeon. The incision portion  11  is translatable in the first hole  922  between a proximal position and a distal position. Furthermore, a distal end portion of the incision portion  11  protrudes outside the distal end member  92  from the first hole  922 . High frequency electric current is passed to the incision portion  11  via the power source cord CO, the plug  822 , and the wire  10 , and an incision is thereby made in a target site in a body cavity. This incision portion  11  includes a knife  12 , as illustrated in  FIG.  2    to  FIG.  5   . 
     The knife  12  is a portion that protrudes outside from the distal end member  92  from the first hole  922  and as illustrated in  FIG.  2   , is formed of a so-called hook knife. This knife  12  includes a knife main body  121  and a projecting portion  122 . 
     The knife main body  121  is positioned on the central axis of the distal end member  92  and is formed of a cylindrical member extending linearly along the central axis. The dimension of the outer diameter of the knife main body  121  is set smaller than the dimension of the inner diameter of the first hole  922 , as illustrated in  FIG.  2    and  FIG.  4   . 
     The projecting portion  122  is a portion provided at a distal end of the knife main body  121  and bent by approximately 90° relatively to the knife main body  121 , upward in  FIG.  2   . 
     The knife  12  described above has a knife hole  123  provided therein, as illustrated in  FIG.  2   , the knife hole  123  penetrating the knife  12  from near a proximal end to a distal end of the knife  12 . This knife hole  123  includes an inflow hole  1231  and an outflow hole  1232 . 
     The inflow hole  1231  is a hole extending toward a central axis of the knife main body  121  from above in  FIG.  2    and  FIG.  5    at a proximal end portion of the knife main body  121 . 
     The outflow hole  1232  is a hole positioned on the central axis of the knife main body  121  and extending linearly along the central axis. The outflow hole  1232  communicates with the exterior of the knife  12  through the projecting portion  122  near a distal end of the outflow hole  1232  and communicates with the outflow hole  1232  near a proximal end of the outflow hole  1232 . 
     A connector  13  is provided near the proximal end of the knife  12 , as illustrated in  FIG.  2    to  FIG.  5   . 
     The connector  13  is a member that connects the knife  12  and the wire  10  to each other. This connector  13  includes a cylindrical portion  131  and a rotation restricting portion  132 . 
     The cylindrical portion  131  is formed of a cylindrical member extending linearly along the central axis of the distal end member  92 . The dimension of the outer diameter of the cylindrical portion  131  is set slightly smaller than the dimension of the distance between the first wall portion  9211  and the second wall portion  9212  and larger than the dimension of the inner diameter of the first hole  922 , as illustrated in  FIG.  5   . The cylindrical portion  131  may preferably be positioned on the central axis of the distal end member  92 . 
     The cylindrical portion  131  has a fitting hole  133  provided therein, the fitting hole  133  extending from a distal end face toward a proximal end (rightward in  FIG.  2   ) of the cylindrical portion  131  and being where the knife main body  121  is fitted into, as illustrated in  FIG.  2   . Furthermore, the cylindrical portion  131  has a communicating hole  134  provided therein, the communicating hole  134  extending toward a central axis of the cylindrical portion  131  from an outer peripheral surface of the cylindrical portion  131  and communicating with the inflow hole  1231 , as illustrated in  FIG.  2    and  FIG.  5   . 
     The knife hole  123 , fitting hole  133 , and communicating hole  134  described above are open on an outer peripheral surface of the incision portion  11  near a proximal end of the incision portion  11  and correspond to a second hole  120  ( FIG.  2   ). The second hole  120  may correspond to a second channel. 
     The rotation restricting portion  132  is a projection protruding from the outer peripheral surface of the cylindrical portion  131  and is inserted in the groove portion  9213 , as illustrated in  FIG.  2    and  FIG.  5   . The rotation restricting portion  132  stays continually inserted in the groove portion  9213  when the incision portion  11  is advancing and retracting in the sheath  9  according to operations on the slider  82  by an operator, such as an operating surgeon. The rotation restricting portion  132  restricts rotation of the knife  12  and the wire  10  about the central axis. 
     The second wall portion  9212  (the groove portion  9213 ) and the rotation restricting portion  132  described above correspond to a rotation restricting structure. 
     Operation of Endoscope Treatment Tool Operation of the above described treatment tool  6  for an endoscope will be described next. A flow of ESD will be described hereinafter as an example for convenience of explanation. 
       FIG.  6    to  FIG.  9    are diagrams illustrating the operation of the endoscope treatment tool  6 . Specifically,  FIG.  6    is a diagram illustrating a marking process in ESD.  FIG.  7    is a diagram illustrating a local injection process in ESD.  FIG.  8    and  FIG.  9    are sectional views corresponding to  FIG.  2   . 
     Firstly, an operator, such as an operating surgeon, inserts the endoscope insertion unit  21  into a body cavity and moves the distal end of the endoscope insertion unit  21  to near a target site T 1  ( FIG.  6   ). 
     Subsequently, the operator, such as an operator surgeon, performs a first operation of retracting the slider  82  toward the operator (toward the ring  811 ). The projecting portion  122  is thereby brought into a state where the projecting portion  122  is in contact with the distal end of the distal end member  92  and only the projecting portion  122  has protruded outside the distal end member  92  from the first hole  922 . The operator, such as an operating surgeon, inserts the treatment tool insertion portion  7  into the duct in the endoscope insertion unit  21  from the insertion opening  223  and causes the treatment tool insertion portion  7  to protrude from the distal end of the endoscope insertion unit  21 . 
     Subsequently, as described hereinafter, an operator, such as an operating surgeon, performs a marking process. 
     That is, the operator, such as an operating surgeon, operates an operating unit (not illustrated in the drawings), such as a foot switch, to pass high frequency electric current to the knife  12  from the power source  100  while maintaining the state where only the projecting portion  122  has protruded outside the distal end member  92  from the first hole  922  through the first operation on the slider  82 . The operator, such as an operating surgeon, then presses the projecting portion  122  against body tissue around the target site T 1  as illustrated at (a) in  FIG.  6   . The body tissue that has come into contact with the projecting portion  122  is thereby cauterized. That is, as illustrated at (a) in  FIG.  6    and (b) in  FIG.  6   , a mark T 2  is formed at the cauterized site. 
     The operator, such as an operating surgeon, repeats the above described operation a plural number of times, to form marks T 2 , as illustrated at (c) in  FIG.  6   , the number of marks T 2  being a number that allows the outline of the target site T 1  to be perceived. Thereafter, the operator, such as an operating surgeon, ends passing the high frequency electric current to the knife  12  from the power source  100 . 
     Subsequently, an operator, such as an operating surgeon, performs a local injection process, as described hereinafter. 
     That is, the operator, such as an operating surgeon, performs a second operation of advancing the slider  82 . The knife  12  thereby protrudes from a distal end of the sheath  9  (the distal end member  92 ) by the maximum protruding length, as illustrated in  FIG.  8   . In this state, the connector  13  is in contact with the bottom portion  920  (a peripheral edge portion of an opening) of the distal end member  92 . The opening of the first hole  922  is thereby closed by the connector  13 , as indicated by marks, “x”, in  FIG.  8   , the opening being near a proximal end of the first hole  922 . That is, the connector  13  corresponds to a second closing portion, the second closing portion enabling the opening of the first hole  922  to be closed, the opening being near the proximal end of the first hole  922 . By contrast, the communicating hole  134  is positioned at a position displaced from a position opposite to the first wall portion  9211 . That is, the position of the communicating hole  134  is displaced from the position of the first wall portion  9211  along a longitudinal axis direction of the sheath  9 . The communicating hole  134  is thereby in communication with the main flow channel M 1 . 
     Furthermore, an operator, such as an operating surgeon, operates an operating unit (not illustrated in the drawings), such as a foot switch, to supply saline solution from the water feeding source  200 , while maintaining the state where the knife  12  has protruded from the distal end of the sheath  9  by the maximum protruding length through the second operation on the slider  82 . The saline solution supplied from the water feeding source  200  is discharged from the distal end of the knife  12  after following a flow channel through the communicating hole  134 , the inflow hole  1231 , and the outflow hole  1232 , from the main flow channel M 1 , as indicated by arrows in  FIG.  8   . The discharged saline solution SL is injected below the target site T 1  by the force of the current of the saline solution SL ( FIG.  7   ). The target site T 1  then floats up from other tissue, such as a submucosal layer below the target site T 1 . 
     Subsequently, an operator, such as an operating surgeon, performs an incision process, as described hereinafter. 
     That is, the operator, such as an operating surgeon, operates an operating unit (not illustrated in the drawings), such as a foot switch, to pass high frequency electric current to the knife  12  from the power source  100  while maintaining the state where the knife  12  has protruded from the distal end of the sheath  9  (the distal end member  92 ) by the maximum protruding length through the second operation on the slider  82 . The operator, such as an operating surgeon, moves the projecting portion  122  along the periphery of the target site T 1  in a state where the projecting portion  122  has been stuck into the body tissue to make an incision along the entire periphery of the target site T 1 , while seeing the marks T 2 . Thereafter, by exfoliation, for example, of the submucosal layer for a mucosal layer including the target site T 1  incised along its entire periphery, the target site T 1  is removed. 
     The ESD is completed by the above processes. When performing irrigation of the surgical site in the above described processes of the ESD, an operator, such as an operating surgeon, performs the following operation. 
     The operator, such as an operating surgeon, sets the state where only the projecting portion  122  has protruded outside the distal end member  92  from the first hole  922  through the first operation on the slider  82 , that is, a state where the projecting portion  122  has protruded from the first hole  922  and the knife main body  121  has been positioned in the first hole  922 . In this state, as illustrated in  FIG.  5    and  FIG.  9   , the communicating hole  134  is positioned at a position opposite to the first wall portion  9211 . That is, the position of the communicating hole  134  is aligned with the position of the first wall portion  9211 , in a longitudinal axis direction of the sheath  9 . In this state, the first wall portion  9211  is in contact with the outer peripheral surface (a peripheral edge portion of an opening) of the cylindrical portion  131  and the communicating hole  134  (the opening of the second hole  120 , the opening being near a proximal end of the second hole  120 ) is thereby closed by the first wall portion  9211  as indicated by the marks, “x”, in  FIG.  9   . That is, the first wall portion  9211  corresponds to a first closing portion, the first closing portion being arranged in the sheath  9  and enabling the opening of the incision portion  11  to be closed, the opening being near the proximal end of the incision portion  11 . By contrast, the first hole  922  is released from the closure by the connector  13  and is in communication with the main flow channel M 1 . 
     Subsequently, an operator, such as an operating surgeon, operates an operating unit (not illustrated in the drawings), such as a foot switch, to cause saline solution to be supplied from the water feeding source  200 . The saline solution supplied from the water feeding source  200  is thereby discharged from the distal end of the sheath  9  (the distal end member  92 ) and supplied to the surgical site in the body cavity, after following a flow channel through the first hole  922  from the main flow channel M 1 , as indicated by arrows in  FIG.  9   . An opening between an inner peripheral surface of the first hole  922  and an outer peripheral surface of the knife main body  121  has an area larger than that of an opening of the outflow hole  1232 . Therefore, the surgical site is irrigated with the saline solution discharged from the distal end of the sheath  9  (the distal end member  92 ). 
     As described above, in this first embodiment, the main flow channel M 1  is capable of communicating with each of the first hole  922  and the second hole  120 , near the distal end of the sheath  9  (the distal end member  92 ). Furthermore, in this configuration, switching between a first mode and a second mode is enabled by advancement and retraction of the incision portion  11  according to operations on the slider  82  by an operator, such as an operating surgeon. The first mode is set by movement of the incision portion  11  toward the proximal end of the sheath  9  and is a mode where saline solution is passed to flow into a body cavity by the main flow channel M 1  and the first hole  922  communicating with each other. More specifically, the first mode is a state where the main flow channel M 1  and the first hole  922  are in communication with each other, and the opening of the incision portion  11  is closed by the first wall portion  9211 , the opening being near the proximal end of the incision portion  11 . The second mode is set by movement of the incision portion  11  toward the distal end of the sheath  9  and is a mode where saline solution is passed to flow into the body cavity by the main flow channel M 1  and the second hole  120  communicating with each other. More specifically, the second mode is a state where the main flow channel M 1  and the second hole  120  are in communication with each other and the opening of the first hole  922  is closed by the connector  13 , the opening being near the proximal end of the first hole  922 . 
     The above described first embodiment has the following effects. 
     The main flow channel M in the endoscope treatment tool  6 , according to the first embodiment, is capable of communicating with each of the first and second holes  922  and  120  near the distal end of the sheath  9  (the distal end member  92 ). In other words, a flow channel where saline solution is to flow through in the treatment tool insertion portion  7  includes a single flow channel (the main flow channel M 1 ) from near the proximal end of the treatment tool insertion portion  7  to near the distal end of the treatment tool insertion portion  7  and branches into two (the first and second holes  922  and  120 ) near the distal end of the sheath  9  (the distal end member  92 ). 
     Furthermore, an operator, such as an operating surgeon, is able to switch the endoscope treatment tool  6 , according to the first embodiment, between the first and second modes by performing the first and second operations on the slider  82 , the first and second operations being uncomplicated operations. Therefore, each of the local injection process and another process in ESD is able to be executed by means of the mere single treatment tool  6  for an endoscope without change of treatment tools between the local injection process and the other process. 
     Therefore, the endoscope treatment tool  6 , according to the first embodiment, enables improvement in user-friendliness. 
     Furthermore, the rotating restricting structure (the second wall portion  9212  (the groove portion  9213 ) and the rotation restricting portion  132 ) that restricts rotation of the incision portion  11  about the central axis is provided between the incision portion  11  and the sheath  9  in the endoscope treatment tool  6 , according to the first embodiment. Therefore, a so-called hook knife that needs to avoid rotating about the central axis is able to be adopted as the knife  12 . 
     Second Embodiment 
     A second embodiment will be described next. 
     In the following description, any component that is the same as that of the above described first embodiment will be assigned with the same reference sign, and detailed description thereof will be omitted or simplified. 
     The distal end portion of the treatment tool insertion portion  7  of the endoscope treatment tool  6 , described above with respect to the first embodiment, is differently configured in an endoscope treatment tool  6 , according to the second embodiment. For convenience of explanation, a treatment tool insertion portion according to the second embodiment will hereinafter be referred to as a treatment tool insertion portion  7 A. 
       FIG.  10    and  FIG.  11    are diagrams illustrating a configuration of the treatment tool insertion portion  7 A according to the second embodiment. Specifically,  FIG.  10    is a sectional view corresponding to  FIG.  2   .  FIG.  11    is a sectional view of the treatment tool insertion portion  7 A at a position of a line XI-XI illustrated in  FIG.  10   . 
     The sheath  9  and the incision portion  11  of the treatment tool insertion portion  7  described above with respect to the first embodiment are differently configured in the treatment tool insertion portion  7 A, as illustrated in  FIG.  10    and  FIG.  11   . For convenience of explanation, a sheath and an incision portion according to the second embodiment will hereinafter be referred to as a sheath  9 A and an incision portion  11 A, respectively. 
     As illustrated in  FIG.  10    and  FIG.  11   , the distal end member  92  of the sheath  9  described above with respect to the first embodiment is differently shaped in the sheath  9 A. For convenience of explanation, a distal end member according to the second embodiment will hereinafter be referred to as a distal end member  92 A. 
     The distal end member  92 A may be formed of a single part or may be formed of a combination of plural parts. 
     As illustrated in  FIG.  10    and  FIG.  11   , a third wall portion  9214  is provided in the distal end member  92 A, instead of the first and second wall portions  9211  and  9212  of the distal end member  92  described above with respect to the first embodiment. 
     As illustrated in  FIG.  10    and  FIG.  11   , the third wall portion  9214  includes a pair of supporting portions  9215  and a ring portion  9216 . 
     As illustrated in  FIG.  10    and  FIG.  11   , each of the pair of supporting portions  9215  protrudes linearly toward a central axis of the distal end member  92 A from an inner peripheral surface  921 . 
     The ring portion  9216  has a ring shape having an axis that is the same as the central axis of the distal end member  92 A and an outer peripheral surface of the ring portion  9216  is connected to tips of the pair of supporting portions  9215 , as illustrated in  FIG.  11   . 
     Furthermore, as illustrated in  FIG.  10   , the first hole  922  in the distal end member  92  described above with respect to the first embodiment is differently shaped in the distal end member  92 A. For convenience of explanation, a first hole according to the second embodiment will hereinafter be referred to as a first hole  922 A. 
     The first hole  922 A has a circular cross-section and extends linearly along the central axis of the distal end member  92 A. Furthermore, as illustrated in  FIG.  10   , a distal end portion of the first hole  922 A increases in diameter toward a distal end of the first hole  922 A. The dimension of the inner diameter of a proximal end portion of the first hole  922 A is set smaller than the dimension of the inner diameter of the inner peripheral surface  921 . Furthermore, the dimension of the inner diameter of the first hole  922 A is set larger than the dimension of the outer diameter of a knife main body  121 . The first hole  922 A may preferably be positioned on the central axis of the distal end member  92 A. 
     As illustrated in  FIG.  10    and  FIG.  11   , the knife  12  and the connector  13  of the incision portion  11  described above with respect to the first embodiment are differently shaped in the incision portion  11 A, as illustrated in  FIG.  10    and  FIG.  11   . For convenience of explanation, a knife and a connector according to the second embodiment will hereinafter be referred to as a knife  12 A and a connector  13 A, respectively. 
     As illustrated in  FIG.  10   , the projecting portion  122  of the knife  12  described above with respect to the first embodiment is differently shaped in the knife  12 A. For convenience of explanation, a projecting portion according to the second embodiment will hereinafter be referred to as a projecting portion  122 A. 
     The projecting portion  122 A has a disk shape having an axis that is the same as a central axis of the knife main body  121 . The dimension of the outer diameter of the projecting portion  122 A is set smaller than the dimension of the inner diameter of the distal end portion of the first hole  922 A, as illustrated in  FIG.  10   . 
     Furthermore, as illustrated in  FIG.  10   , the knife hole  123  in the knife  12  described above with respect to the first embodiment is differently shaped in the knife  12 A. For convenience of explanation, a knife hole according to the second embodiment will hereinafter be referred to as a knife hole  123 A. 
     As illustrated in  FIG.  10   , the knife hole  123 A is positioned on the central axis of the knife main body  121  and linearly penetrates the knife main body  121  from a proximal end of the knife main body  121  to a distal end face of the projecting portion  122 A, along the central axis. 
     The connector  13 A is formed of a cylindrical member extending linearly along the central axis of the distal end member  92 A. The dimension of the outer diameter of the connector  13 A is set slightly smaller than the dimension of the inner diameter of the ring portion  9216  ( FIG.  11   ) and larger than the dimension of the inner diameter of the proximal end portion of the first hole  922 A. Furthermore, as illustrated in  FIG.  10    and  FIG.  11   , first and second communicating holes  135  and  136  are provided in the connector  13 A. The connector  13 A may preferably be positioned on the central axis of the distal end member  92 A. 
     The first communicating hole  135  extends linearly along the central axis from a distal end of the connector  13 A toward a proximal end of the connector  13 A, as illustrated in  FIG.  10   . In a state where the connector  13 A and the knife main body  121  have been connected to each other, the first communicating hole  135  is in communication with the knife hole  123 A. The first communicating hole  135  may preferably be positioned on a central axis of the connector  13 A. 
     The second communicating hole  136  is a cross-shaped hole that communicates with the first communicating hole  135  and communicates with an opening on an outer peripheral surface of the connector  13 A. 
     The above described knife hole  123 A and first and second communicating holes  135  and  136  are open on the outer peripheral surface of the incision portion  11 A, the outer peripheral surface being near a proximal end of the incision portion  11 A, and correspond to a second hole  120 A ( FIG.  10   ). 
     Operation of the endoscope treatment tool  6 , according to the second embodiment, will be described next. For convenience of explanation, a flow of ESD will hereinafter be described as an example, similarly to the above described first embodiment. 
       FIG.  12    and  FIG.  13    are diagrams illustrating the operation of the endoscope treatment tool  6 . Specifically,  FIG.  12    and  FIG.  13    are sectional views corresponding to  FIG.  10   . 
     In this second embodiment, an operator, such as an operating surgeon, performs a local injection process as described below. 
     That is, the operator, such as an operating surgeon, sets a state where the knife  12 A has protruded from a distal end of the sheath  9 A (the distal end member  92 A) by the maximum protruding length, by performing a second operation on the slider  82 . In this state, the connector  13 A is in contact with a bottom portion  920  (a peripheral edge portion of an opening) of the distal end member  92 A. The opening of the first hole  922 A is thereby closed by the connector  13 A, as indicated by the marks, “x”, in  FIG.  12   , the opening being near a proximal end of the first hole  922 A. That is, the connector  13 A corresponds to a second closing portion, the second closing portion enabling the opening of the first hole  922 A to be closed, the opening being near the proximal end of the first hole  922 A. Furthermore, the connector  13 A is positioned in a distal direction from the ring portion  9216 . That is, the second communicating hole  136  is not closed by an inner peripheral surface of the ring portion  9216  and is in communication with a main flow channel M 1 . 
     Subsequently, an operator, such as an operating surgeon, operates an operating unit (not illustrated in the drawings), such as a foot switch, to cause saline solution to be supplied from the water feeding source  200 , while maintaining the state where the knife  12 A has protruded from the distal end of the sheath  9 A by the maximum protruding length through the second operation on the slider  82 . The saline solution supplied from the water feeding source  200  is thereby discharged from a distal end of the knife  12 A after following a flow channel through the first and second communicating holes  135  and  136  and the knife hole  123 A, from the main flow channel M 1 , as indicated by arrows in  FIG.  12   . The discharged saline solution is injected below a target site T 1 . The target site T 1  then floats up from other tissue, such as a submucosal layer below the target site T 1 . 
     A marking process and an incision process are similar to those of the first embodiment described above, and description thereof will thus be omitted. 
     Furthermore, when performing irrigation of the surgical site in the processes of ESD, an operator, such as an operating surgeon, performs the following operation. 
     The operator, such as an operating surgeon, sets a state where only the projecting portion  122 A has protruded outside the distal end member  92 A from the first hole  922 A, by performing a first operation on the slider  82 . In this state, as illustrated in  FIG.  11    and  FIG.  13   , the connector  13 A is inserted in the ring portion  9216  and the second communicating hole  136  is positioned at a position opposite to the inner peripheral surface of the ring portion  9216 . That is, the inner peripheral surface of the ring portion  9216  comes into contact with the outer peripheral surface (a peripheral edge portion of an opening) of the connector  13 A, and the second communicating hole  136  (an opening of the second hole  120 A, the opening being near a proximal end of the second hole  120 A) is thereby closed by the inner peripheral surface of the ring portion  9216 , as indicated by the marks, “x”, in  FIG.  13   . That is, the ring portion  9216  corresponds to a first closing portion, the first closing portion being arranged in the sheath  9 A and enabling the opening of the incision portion  11 A to be closed, the opening being near the proximal end of the incision portion  11 A. By contrast, the first hole  922 A is released from the closure by the connector  13 A and is in communication with the main flow channel M 1 . 
     Subsequently, an operator, such as an operating surgeon, causes saline solution to be supplied from the water feeding source  200 , by operating an operating unit (not illustrated in the drawings), such as a foot switch, while maintaining the state where only the projecting portion  122 A has protruded outside the distal end member  92 A from the first hole  922 A through the first operation on the slider  82 . The saline solution supplied from the water feeding source  200  is thereby discharged from the distal end of the sheath  9 A and supplied to the surgical site in a body cavity, after following a flow channel through the first hole  922 A from the main flow channel M 1 , as indicated by arrows in  FIG.  13   . An opening between an inner peripheral surface of the first hole  922 A and an outer peripheral surface of the knife main body  121  has an area larger than that of an opening of the knife hole  123 A. Therefore, the surgical site is irrigated with the saline solution discharged from the distal end of the sheath  9 A (the distal end member  92 A). 
     As described above, similarly to the above described first embodiment, in this second embodiment also, the main flow channel M 1  is capable of communicating with each of the first hole  922 A and the second hole  120 A, near the distal end of the sheath  9 A (the distal end member  92 A). Furthermore, in this configuration, switching between a first mode and a second mode is enabled by advancement and retraction of the incision portion  11 A according to operations on the slider  82  by an operator, such as an operating surgeon. The first mode is set by movement of the incision portion  11 A toward a proximal end of the sheath  9 A and is a mode where saline solution is passed to flow into a body cavity by the main flow channel M 1  and the first hole  922 A communicating with each other. More specifically, the first mode is a state where the main flow channel M 1  and the first hole  922 A are in communication with each other and the opening of the incision portion  11 A is closed by the ring portion  9216 , the opening being near the proximal end of the incision portion  11 A. The second mode is set by movement of the incision portion  11 A toward the distal end of the sheath  9 A and is a mode where saline solution is passed to flow into the body cavity by the main flow channel M 1  and the second hole  120 A communicating with each other. More specifically, the second mode is a state where the main flow channel M 1  and the second hole  120 A are in communication with each other and the opening of the first hole  922 A is closed by the connector  13 A, the opening being near the proximal end of the first hole  922 A. 
     In a case where the treatment tool insertion portion  7 A according to the second embodiment described above is adopted also, effects similar to those of the above described first embodiment are achieved. 
     Modified Example of Second Embodiment 
       FIG.  14    is a diagram illustrating a modified example of the second embodiment. Specifically,  FIG.  14    is a sectional view corresponding to  FIG.  10   . 
     The distal end portion of the first hole  922 A in the above described second embodiment may be configured to have a shape illustrated in  FIG.  14   . Specifically, a distal end portion of a first hole  922 A according to the modified example illustrated in  FIG.  14    linearly extends toward a distal end thereof along a central axis of a distal end member  92 A, in a state of having the same diameter dimension after increasing in diameter toward the distal end. 
     Third Embodiment 
     A third embodiment will be described next. 
     In the following description, any component that is the same as that of the above described first embodiment will be assigned with the same reference sign, and detailed description thereof will be omitted or simplified. 
     The distal end portion of the treatment tool insertion portion  7  of the endoscope treatment tool  6 , described above with respect to the first embodiment, is differently configured in an endoscope treatment tool  6 , according to the third embodiment. For convenience of explanation, a treatment tool insertion portion according to the third embodiment will hereinafter be referred to as a treatment tool insertion portion  7 B. 
       FIG.  15    and  FIG.  16    are diagrams illustrating a configuration of the treatment tool insertion portion  7 B according to the third embodiment. Specifically,  FIG.  15    is a sectional view corresponding to  FIG.  2   .  FIG.  16    is a sectional view of the treatment tool insertion portion  7 B at a position of a line XVI-XVI illustrated in  FIG.  15   . 
     The sheath  9 , the wire  10 , and the incision portion  11 , of the treatment tool insertion portion  7  described above with respect to the first embodiment are differently configured in the treatment tool insertion portion  7 B, as illustrated in  FIG.  15    and  FIG.  16   . For convenience of explanation, a sheath, a wire, and an incision portion, according to the third embodiment, will hereinafter be referred to as a sheath  9 B, a wire  10 B, and an incision portion  11 B, respectively. 
     As illustrated in  FIG.  15    and  FIG.  16   , the distal end member  92  of the sheath  9  described above with respect to the first embodiment is differently shaped in the sheath  9 B. For convenience of explanation, a distal end member according to the third embodiment will hereinafter be referred to as a distal end member  92 B. 
     The distal end member  92 B may be formed of a single part or may be formed of a combination of plural parts. 
     As illustrated in  FIG.  15   , the first and second wall portions  9211  and  9212  of the distal end member  92  described above with respect to the first embodiment are omitted from the distal end member  92 B, as illustrated in  FIG.  15   . 
     Furthermore, as illustrated in  FIG.  15    and  FIG.  16   , the first hole  922  in the distal end member  92  described above with respect to the first embodiment is differently shaped in the distal end member  92 B. For convenience of explanation, a first hole according to the third embodiment will hereinafter be referred to as a first hole  922 B. 
     The first hole  922 B has a circular cross-section and extends linearly along a central axis of the distal end member  92 B. Furthermore, as illustrated in  FIG.  15   , a distal end portion of the first hole  922 B increases in diameter toward a distal end of the first hole  922 B. The dimension of the inner diameter of a proximal end portion of the first hole  922 B is set smaller than the dimension of the inner diameter of an inner peripheral surface  921 . Furthermore, the dimension of the inner diameter of the distal end portion of the first hole  922 B is set larger than the dimension of the outer diameter of a projecting portion  122 A. In addition, the dimension of the inner diameter of the first hole  922 B is set larger than the dimension of the outer diameter of a knife main body  121 . The first hole  922 B may preferably be positioned on the central axis of the distal end member  92 B. 
     Furthermore, a pair of fourth wall portions  9221  ( FIG.  15    and  FIG.  16   ) and a fifth wall portion  9222  ( FIG.  15   ) are provided on an inner surface of the first hole  922 B. 
     As illustrated in  FIG.  15    and  FIG.  16   , the pair of fourth wall portions  9221  are walls each protruding toward a central axis of the first hole  922 B from upper and lower portions in  FIG.  15    and  FIG.  16    on the inner surface of the first hole  922 B, the upper and inner portions being opposite to each other. The dimension of the distance between tips of the pair of fourth wall portions  9221  is set slightly larger than the dimension of the outer diameter of the knife main body  121 . 
     The fifth wall portion  9222  is a ring-shaped wall having the same axis as the central axis of the first hole  922 B. The dimension of the inner diameter of the fifth wall portion  9222  is set slightly larger than the dimension of the outer diameter of the knife main body  121 . 
     As illustrated in  FIG.  15   , the wire  10 B is differently shaped from the wire  10  described above with respect to the first embodiment and has a cylindrical shape. Furthermore, a through hole  101  in the wire  10 B communicates with the water feeding port  812 . The through hole  101  functions as a main flow channel M 1 , the main flow channel M 1  being where saline solution supplied from the water feeding source  200  flows through via the tube TU and the water feeding port  812 . 
     As illustrated in  FIG.  15    and  FIG.  16   , the connector  13  of the incision portion  11  described above with respect to the first embodiment is omitted, and the knife  12  of the incision portion  11  is differently shaped, in the incision portion  11 B. For convenience of explanation, a knife according to the third embodiment will hereinafter be referred to as a knife  12 B. 
     As illustrated in  FIG.  15   , the knife  12 B has an outer shape that is the same as that of the knife  12 A described above with respect to the second embodiment. That is, the knife  12 B includes the knife main body  121  and the projecting portion  122 A. The knife main body  121  is directly connected to the wire  10 B. In this third embodiment, a proximal end portion of an outer peripheral surface of the knife main body  121  has an abutting portion  1211  provided thereon, the abutting portion  1211  protruding from the outer peripheral surface, extending over the entire periphery of the knife main body  121 , and being ring-shaped, the entire periphery being along a circumferential direction and about a central axis of the knife main body  121 . 
     Furthermore, as illustrated in  FIG.  15   , the knife hole  123 A in the knife  12 A described above with respect to the second embodiment is differently shaped in the knife  12 B. For convenience of explanation, a knife hole according to the third embodiment will hereinafter be referred to as a knife hole  123 B. 
     The knife hole  123 B includes a second hole main body  1233  ( FIG.  15   ) and a communicating hole  1234  ( FIG.  15    and  FIG.  16   ). 
     As illustrated in  FIG.  15   , the second hole main body  1233  is positioned on the central axis of the knife main body  121  and linearly penetrates the knife main body  121  from a proximal end of the knife main body  121  to a distal end face of the projecting portion  122 A. In a state where the knife main body  121  and the wire  10 B have been connected to each other, the second hole main body  1233  is in communication with the through hole  101 . 
     The communicating hole  1234  is an I-shaped hole that is positioned at an approximately central portion of the longitudinal length of the knife main body  121 , communicates with the second hole main body  1233 , extends along a vertical direction (a radial direction of the knife main body  121 ) in  FIG.  15    and  FIG.  16   , and is open on the outer peripheral surface of the knife main body  121 . 
     The knife hole  123 B described above corresponds to a second hole  120 B ( FIG.  15   ). 
     Operation of an endoscope treatment tool  6 , according to the third embodiment, will be described next. For convenience of explanation, a flow of ESD will hereinafter be described as an example, similarly to the above described first embodiment. 
       FIG.  17    and  FIG.  18    are diagrams illustrating the operation of the endoscope treatment tool  6 . Specifically,  FIG.  17    and  FIG.  18    are sectional views corresponding to  FIG.  15   . 
     In this third embodiment, an operator, such as an operating surgeon, performs a local injection process as described below. 
     That is, the operator, such as an operating surgeon, sets a state where the knife  12 B has protruded from a distal end of the sheath  9 B (the distal end member  92 B) by the maximum protruding length, by performing a second operation on the slider  82 . In this state, the abutting portion  1211  is in contact with a bottom portion  920  (a peripheral edge portion of an opening) of the distal end member  92 B. The knife  12 B is thereby restricted from moving to a distal end. Furthermore, the communicating hole  1234  is positioned at a position opposite to the pair of fourth wall portions  9221 . In this state, the pair of fourth wall portions  9221  are in contact with the outer peripheral surface (the peripheral edge portion of the opening) of the knife main body  121  and a flow channel between the first hole  922 B and the communicating hole  1234  is thereby blocked by the pair of fourth wall portions  9221  as indicated by the marks, “x”, in  FIG.  17   . 
     Subsequently, an operator, such as an operating surgeon, operates an operating unit (not illustrated in the drawings), such as a foot switch, to cause saline solution to be supplied from the water feeding source  200 , while maintaining the state where the knife  12 B has protruded from the distal end of the sheath  9 B by the maximum protruding length through the second operation on the slider  82 . The saline solution supplied from the water feeding source  200  is thereby discharged from a distal end of the knife  12 B after following a flow channel through the knife hole  123 B from the main flow channel M 1 , as indicated by an arrow in  FIG.  17   . The discharged saline solution is injected below a target site T 1  by the force of the current of the saline solution. The target site T 1  then floats up from other tissue, such as a submucosal layer below the target site T 1 . 
     A marking process and an incision process are similar to those of the first embodiment described above, and description thereof will thus be omitted. 
     Furthermore, when performing irrigation of the surgical site in the processes of the ESD, an operator, such as an operating surgeon, performs the following operation. 
     The operator, such as an operating surgeon, sets a state where only the projecting portion  122 A has protruded outside the distal end member  92 B from the first hole  922 B, by performing a first operation on the slider  82 . In this state, the communicating hole  1234  is positioned at a position displaced from the position opposite to the pair of fourth wall portions  9221 , as illustrated in  FIG.  18   . The communicating hole  1234  is thereby in communication with the first hole  922 B. 
     Subsequently, an operator, such as an operating surgeon, causes saline solution to be supplied from the water feeding source  200 , by operating an operating unit (not illustrated in the drawings), such as a foot switch, while maintaining the state where only the projecting portion  122 A has protruded outside the distal end member  92 B from the first hole  922 B through the first operation on the slider  82 . The saline solution supplied from the water feeding source  200  is thereby discharged from the distal end of the knife  12 B after following the flow channel through the knife hole  123 B from the main flow channel M 1  as indicated by an arrow in  FIG.  18   , and discharged from the distal end of the sheath  9 B after following a flow channel through the knife hole  123 B, communicating hole  1234 , and first hole  922 B, from the main flow channel M 1 , to be supplied to the surgical site. The saline solution that has followed the main flow channel M 1  is discharged from both the knife hole  123 B and the first hole  922 B. Therefore, the surgical site is irrigated with the saline solution discharged from both the knife hole  123 B and the first hole  922 B. 
     As described above, similarly to the above described first embodiment, in this third embodiment also, the main flow channel M 1  is capable of communicating with each of the first hole  922 B and the second hole  120 B, near the distal end of the sheath  9 B (the distal end member  92 B). Furthermore, in this configuration, switching between a first mode and a second mode is enabled by advancement and retraction of the incision portion  11 B according to operations on the slider  82  by an operator, such as an operating surgeon. The first mode is set by movement of the incision portion  11 B toward a proximal end of the sheath  9 B and is a mode where saline solution is passed to flow into a body cavity by the main flow channel M 1  communicating with the first hole  922 B and the second hole  120 B. The second mode is set by movement of the incision portion  11 B toward the distal end of the sheath  9 B and is a mode where saline solution is passed to flow into the body cavity by the main flow channel M 1  communicating with the second hole  120 B. 
     In a case where the treatment tool insertion portion  7 B according to the third embodiment described above is adopted also, effects similar to those of the above described first embodiment are achieved. 
     Fourth Embodiment 
     A fourth embodiment will be described next. 
     In the following description, any component that is the same as that of the above described first embodiment will be assigned with the same reference sign, and detailed description thereof will be omitted or simplified. 
     The distal end portion of the treatment tool insertion portion  7  in the endoscope treatment tool  6 , described above with respect to the first embodiment, is differently configured in an endoscope treatment tool  6 , according to the fourth embodiment. For convenience of explanation, a treatment tool insertion portion according to the fourth embodiment will hereinafter be referred to as a treatment tool insertion portion  7 C. 
       FIG.  19    to  FIG.  23    are diagrams illustrating a configuration of the treatment tool insertion portion  7 C according to the fourth embodiment. Specifically,  FIG.  19    is a sectional view corresponding to  FIG.  2   .  FIG.  20    is a sectional view of the treatment tool insertion portion  7 C at a position of a line XX-XX illustrated in  FIG.  19   .  FIG.  21    is a sectional view of the treatment tool insertion portion  7 C at a position of a line XXI-XXI illustrated in  FIG.  19   .  FIG.  22    is a sectional view of the treatment tool insertion portion  7 C at a position of a line XXII-XXII illustrated in  FIG.  19   .  FIG.  23    is a sectional view of the treatment tool insertion portion  7 C at a position of a line XXIII-XXIII illustrated in  FIG.  19   . 
     The sheath  9  and the incision portion  11  of the treatment tool insertion portion  7  described above with respect to the first embodiment are differently configured in the treatment tool insertion portion  7 C, as illustrated in  FIG.  19    to  FIG.  23   . For convenience of explanation, a sheath and an incision portion according to the fourth embodiment will hereinafter be referred to as a sheath  9 C and an incision portion  11 C, respectively. 
     As illustrated in  FIG.  19    to  FIG.  23   , the distal end member  92  of the sheath  9  described above with respect to the first embodiment is differently shaped in the sheath  9 C. For convenience of explanation, a distal end member according to the third embodiment will hereinafter be referred to as a distal end member  92 C. 
     The distal end member  92 C may be formed of a single part or may be formed of a combination of plural parts. 
     The first wall portion  9211  of the distal end member  92  described above with respect to the first embodiment is omitted from the distal end member  92 C, as illustrated in  FIG.  19   . 
     Furthermore, as illustrated in  FIG.  19    and  FIG.  20   , the first hole  922  in the distal end member  92  described above with respect to the first embodiment is differently shaped in the distal end member  92 C. For convenience of explanation, a first hole according to the fourth embodiment will hereinafter be referred to as a first hole  922 C. 
     The upper shape of the first hole  922 C in  FIG.  19    and  FIG.  20    is different from that of the first hole  922  described above with respect to the first embodiment. Specifically, an upper portion of the first hole  922 C has a predetermined clearance from a knife main body  121 , and the first hole  922 C (an inner peripheral surface of the distal end member  92 C) extends in a radial direction and communicates with a main flow channel M 1 . 
     As illustrated in  FIG.  19    to  FIG.  23   , the knife  12  and the connector  13  of the incision portion  11  described above with respect to the first embodiment are differently shaped in the incision portion  11 C. For convenience of explanation, a knife and a connector according to the fourth embodiment will hereinafter be referred to as a knife  12 C and a connector  13 C, respectively. 
     As illustrated in  FIG.  19   , the knife  12 C has an outer shape that is the same as the knife  12 A described above with respect to the second embodiment. That is, the knife  12 C includes the knife main body  121  and a projecting portion  122 A. 
     Furthermore, as illustrated in  FIG.  19   , the knife hole  123 A in the knife  12 A described above with respect to the second embodiment is differently shaped in the knife  12 C. For convenience of explanation, a knife hole according to the fourth embodiment will hereinafter be referred to as a knife hole  123 C. 
     The knife hole  123 C includes a second hole main body  1235  ( FIG.  19    and  FIG.  20   ) and a communicating hole  1236  ( FIG.  19    and  FIG.  21   ). 
     The second hole main body  1235  extends linearly along a central axis of the knife main body  121  from a distal end face of the projecting portion  122 A, in a proximal direction, as illustrated in  FIG.  19   . The second hole main body  1235  may preferably positioned on the central axis of the knife main body  121 . 
     As illustrated in  FIG.  19    and  FIG.  21   , the communicating hole  1236  communicates with a proximal end portion of the second hole main body  1235 , extends toward an outer peripheral surface of the knife main body  121  in  FIG.  19    and  FIG.  21   , and is open on the outer peripheral surface of the knife main body  121 . 
     The knife hole  123 C described above is open on an outer peripheral surface of the incision portion  11 C, the outer peripheral surface being near a proximal end of the incision portion  11 C, and corresponds to a second hole  120 C ( FIG.  19   ). 
     As illustrated in  FIG.  19    and  FIG.  21    to  FIG.  23   , the communicating hole  134  in the connector  13  described above with respect to the first embodiment is omitted from the connector  13 C. For convenience of explanation, illustration of a fitting hole  133  is omitted in  FIG.  19    and  FIG.  21    to  FIG.  23   . 
     Operation of an endoscope treatment tool  6 , according to the fourth embodiment, will be described next. For convenience of explanation, a flow of ESD will hereinafter be described as an example, similarly to the above described first embodiment. 
       FIG.  24    and  FIG.  25    are diagrams illustrating the operation of the endoscope treatment tool  6 . Specifically,  FIG.  24    and  FIG.  25    are sectional views corresponding to  FIG.  19   . 
     In this fourth embodiment, an operator, such as an operating surgeon, performs a local injection process as described below. 
     That is, the operator, such as an operating surgeon, sets a state where only the projecting portion  122 A has protruded outside the distal end member  92 C from the first hole  922 C, that is, a state where the projecting portion  122 A has protruded from the first hole  922 C and the knife main body  121  has been positioned in the first hole  922 C, by performing a first operation on the slider  82 . In this state, as illustrated in  FIG.  24   , the communicating hole  1236  is positioned at a position separate from an inner surface of the first hole  922 C and a clearance is generated. The communicating hole  1236  is thereby in communication with the main flow channel M 1  via this clearance. By contrast, as indicated by the marks, “x”, in  FIG.  24   , the projecting portion  122 A is in contact with a distal end of the sheath  9 C (the distal end member  92 C) and the first hole  922 C is thus closed near a distal end of the first hole  922 C by the projecting portion  122 A. That is, the projecting portion  122 A corresponds to a second closing portion, the second closing portion enabling an opening of the first hole  922 C to be closed, the opening being near the distal end of the first hole  922 C. 
     Subsequently, an operator, such as an operating surgeon, causes saline solution to be supplied from the water feeding source  200 , by operating an operating unit (not illustrated in the drawings), such as a foot switch, while maintaining the state where only the projecting portion  122 A has protruded outside the distal end member  92 C from the first hole  922 C through the first operation on the slider  82 . The saline solution supplied from the water feeding source  200  is thereby discharged from a distal end of the knife  12 C after following a flow channel through the communicating hole  1236  and the second hole main body  1235 , from the main flow channel M 1 , as indicted by arrows in  FIG.  24   . The discharged saline solution is injected below a target site T 1  by the force of the current of the saline solution. The target site T 1  then floats up from other tissue, such as a submucosal layer below the target site T 1 . 
     A marking process and an incision process are similar to those of the first embodiment described above, and description thereof will thus be omitted. 
     Furthermore, when performing irrigation of the surgical site in the processes of the ESD, an operator, such as an operating surgeon, performs the following operation. 
     The operator, such as an operating surgeon, sets a state where the knife  12 C has protruded from the distal end of the sheath  9 C by the maximum protruding length, by performing a second operation on the slider  82 . In this state, as illustrated in  FIG.  25   , the communicating hole  1236  is positioned at a position where the communicating hole  1236  is in contact with an inner surface of the first hole  922 C. A flow channel between the communicating hole  1236  and the main flow channel M 1  is thereby blocked by the inner surface of the first hole  922 C as indicated by the mark, “x”, in  FIG.  25   . That is, the inner surface of the first hole  922 C corresponds to a first closing portion, the first closing portion being arranged in the sheath  9 C and being capable of closing an opening of the incision portion  11 C, the opening being near a proximal end of the incision portion  11 C. By contrast, in this state, the first hole  922 C is released from the closure near the distal end of the first hole  922 C by the projecting portion  122 A because the projecting portion  122 A is separate from the distal end of the sheath  9 C (the distal end member  92 C). 
     Subsequently, an operator, such as an operating surgeon, causes saline solution to be supplied from the water feeding source  200  by operating an operating unit (not illustrated in the drawings), such as a foot switch, while maintaining the state where the knife  12 C has protruded from the distal end of the sheath  9 C by the maximum protruding length through the second operation on the slider  82 . The saline solution supplied from the water feeding source  200  is thereby discharged from the distal end of the sheath  9 C and supplied to the surgical site, after following a flow channel through the first hole  922 C from the main flow channel M 1 , as indicated by arrows in  FIG.  25   . An opening between the inner peripheral surface of the first hole  922 C and the outer peripheral surface of the knife main body  121  has an area larger than that of an opening of the second hole main body  1235 . Therefore, the surgical site is irrigated with the saline solution discharged from the distal end of the sheath  9 C (the distal end member  92 C). 
     As described above, in this fourth embodiment, similarly to the above described first embodiment, the main flow channel M 1  is capable of communicating with each of the first hole  922 C and the second hole  120 C, near the distal end of the sheath  9 C (the distal end member  92 C). Furthermore, in this configuration, switching between a first mode and a second mode is enabled by advancement and retraction of the incision portion  11 C according to operations on the slider  82  by an operator, such as an operating surgeon. The first mode is set by movement of the incision portion  11 C toward the distal end of the sheath  9 C and is a mode where saline solution is passed to flow into a body cavity by the main flow channel M 1  and the first hole  922 C communicating with each other. More specifically, the first mode is a state where the main flow channel M 1  and the first hole  922 C are in communication with each other and the opening of the incision portion  11 C is closed by the inner surface of the first hole  922 C, the opening being near the proximal end of the incision portion  11 C. The second mode is set by movement of the incision portion  11 C toward a proximal end of the sheath  9 C and is a mode where saline solution is passed to flow into the body cavity by the main flow channel M 1  and the second hole  120 C communicating with each other. More specifically, the second mode is a state where the main flow channel M 1  and the second hole  120 C are in communication with each other and the opening of the first hole  922 C is closed by the projecting portion  122 A, the opening being near the distal end of the first hole  922 C. 
     In a case where the treatment tool insertion portion  7 C according to the fourth embodiment described above is adopted also, effects similar to those of the above described first embodiment are achieved. 
     Fifth Embodiment 
     A fifth embodiment will be described next. 
     In the following description, any component that is the same as that of the above described first embodiment will be assigned with the same reference sign, and detailed description thereof will be omitted or simplified. 
     The distal end portion of the treatment tool insertion portion  7  in the endoscope treatment tool  6 , described above with respect to the first embodiment, is differently configured in an endoscope treatment tool  6 , according to the fifth embodiment. For convenience of explanation, a treatment tool insertion portion according to the fifth embodiment will hereinafter be referred to as a treatment tool insertion portion  7 D. 
       FIG.  26    to  FIG.  31    are diagrams illustrating a configuration of the treatment tool insertion portion  7 D according to the fifth embodiment. Specifically,  FIG.  26    is a sectional view corresponding to  FIG.  2   .  FIG.  27    is a sectional view of the treatment tool insertion portion  7 D at a position of a line XXVII-XXVII illustrated in  FIG.  26   .  FIG.  28    is a sectional view of the treatment tool insertion portion  7 D at a position of a line XXVIII-XXVIII illustrated in  FIG.  26   .  FIG.  29    is a sectional view of the treatment tool insertion portion  7 D at a position of a line XXIX-XXIX illustrated in  FIG.  26   .  FIG.  30    is a sectional view of the treatment tool insertion portion  7 D at a position of a line XXX-XXX illustrated in  FIG.  26   .  FIG.  31    is a sectional view of the treatment tool insertion portion  7 D at a position of a line XXXI-XXXI illustrated in  FIG.  26   . 
     The sheath  9  and the incision portion  11  of the treatment tool insertion portion  7  described above with respect to the first embodiment are differently configured in the treatment tool insertion portion  7 D, as illustrated in  FIG.  26    to  FIG.  31   . For convenience of explanation, a sheath and an incision portion according to the fifth embodiment will hereinafter be referred to as a sheath  9 D and an incision portion  11 D, respectively. 
     As illustrated in  FIG.  26    to  FIG.  31   , the distal end member  92  of the sheath  9  described above with respect to the first embodiment is differently shaped in the sheath  9 D. For convenience of explanation, a distal end member according to the fifth embodiment will hereinafter be referred to as a distal end member  92 D. 
     The distal end member  92 D may be formed of a single part or may be formed of a combination of plural parts. 
     As illustrated in  FIG.  26    and  FIG.  31   , the third wall portion  9214  described above with respect to the second embodiment is provided in the distal end member  92 D, instead of the first and second wall portions  9211  and  9212  in the distal end member  92  described above with respect to the first embodiment. A wire  10  is inserted in a ring portion  9216  forming the third wall portion  9214  in this fifth embodiment, as illustrated in  FIG.  31   . 
     As illustrated in  FIG.  26    to  FIG.  30   , the knife  12 A described above with respect to the second embodiment is adopted in the incision portion  11 D, instead of the knife  12  in the incision portion  11  described above with respect to the first embodiment, and the connector  13  in the incision portion  11  is also shaped differently in the incision portion  11 D. For convenience of explanation, a connector according to the fifth embodiment will hereinafter be referred to as a connector  13 D. 
     The connector  13 D is formed of a cylindrical member extending linearly along a central axis of the distal end member  92 D. The dimension of the outer diameter of the connector  13 D is set slightly smaller than the dimension of the inner diameter of the first hole  922  and larger than the dimension of the inner diameter of the ring portion  9216 . Furthermore, as illustrated in  FIG.  26   ,  FIG.  28   , and  FIG.  29   , first and second communicating holes  137  and  138  and a pair of third communicating holes  139  are provided in the connector  13 D. The connector  13 D may preferably be positioned on the central axis of the distal end member  92 D. 
     The first communicating hole  137  extends linearly along a central axis of the connector  13 D from a distal end of the connector  13 D toward a proximal end of the connector  13 D, as illustrated in  FIG.  26   . In a state where the connector  13 D and a knife main body  121  have been connected to each other, the first communicating hole  137  is in communication with a knife hole  123 A. The first communicating hole  137  may preferably be positioned on the central axis of the connector  13 D. 
     The second communicating hole  138  is positioned at an approximately central portion of the longitudinal length of the connector  13 D, communicates with the first communicating hole  137 , extends in a vertical direction (a radial direction of the connector  13 D) in  FIG.  26    and  FIG.  29   , and is an I-shaped hole that is open on an outer peripheral surface of the connector  13 D. 
     The knife hole  123 A and the first and second communicating holes  137  and  138  described above are open on an outer peripheral surface of the incision portion  11 D, the outer peripheral surface being near a proximal end of the incision portion  11 D, and correspond to a second hole  120 D ( FIG.  26   ). 
     As illustrated in  FIG.  28   , the pair of third communicating holes  139  are positioned on both sides of the first communicating hole  137  and are holes linearly penetrating the connector  13 D along the central axis of the connector  13 D from the distal end to the proximal end of the connector  13 D. The pair of third communicating holes  139  do not communicate with the first and second communicating holes  137  and  138 . 
     Operation of an endoscope treatment tool  6 , according to the fifth embodiment, will be described next. For convenience of explanation, a flow of ESD will hereinafter be described as an example, similarly to the above described first embodiment. 
       FIG.  32    and  FIG.  33    are diagrams illustrating the operation of the endoscope treatment tool  6 . Specifically,  FIG.  32    and  FIG.  33    are sectional views corresponding to  FIG.  26   . 
     In this fifth embodiment, an operator, such as an operating surgeon, performs a local injection process as described below. 
     That is, the operator, such as an operating surgeon, sets a state where only a projecting portion  122 A has protruded outside the distal end member  92 D from a first hole  922 , that is, a state where the projecting portion  122 A has protruded from the first hole  922  and the knife main body  121  has been positioned in the first hole  922 , by performing a first operation on the slider  82 . In this state, as illustrated in  FIG.  32   , a distal end portion of the connector  13 D has been inserted in the first hole  922  and the proximal end of the connector  13 D is in contact with a distal end face of the ring portion  9216 . In this state, the distal end portion of the connector  13 D has been inserted in the first hole  922 , the pair of third communicating holes  139  are closed by the ring portion  9216 , and a flow channel between the first hole  922  and a main flow channel M 1  is thereby blocked by the connector  13 D as indicated by the marks, “x” in  FIG.  32   . That is, the connector  13 D corresponds to a third closing portion, the third closing portion enabling an opening of the first hole  922  to be closed, the opening being near a proximal end of the first hole  922 . Furthermore, a flow channel between the pair of third communicating holes  139  and the main flow channel M 1  is blocked by the ring portion  9216 , as indicated by the marks, “x”, in  FIG.  32   . In contrast, the second communicating hole  138  is positioned at a position displaced from an inner surface of the first hole  922 . The second communicating hole  138  is thereby in communication with the main flow channel M 1 . 
     Subsequently, an operator, such as an operating surgeon, causes saline solution to be supplied from the water feeding source  200 , by operating an operating unit (not illustrated in the drawings), such as a foot switch, while maintaining the state where only the projecting portion  122 A has protruded outside the distal end member  92 D from the first hole  922  through the first operation on the slider  82 . The saline solution supplied from the water feeding source  200  is thereby discharged from a distal end of the knife  12 A after following a flow channel through the second communicating hole  138 , the first communicating hole  137 , and the knife hole  123 A, from the main flow channel M 1 , as indicated by arrows in  FIG.  32   . The discharged saline solution is injected below a target site T 1  by the force of the current of the saline solution. The target site T 1  then floats up from other tissue, such as a submucosal layer below the target site T 1 . 
     A marking process and an incision process are similar to those of the first embodiment described above, and description thereof will thus be omitted. 
     Furthermore, when performing irrigation of the surgical site in the processes of the ESD, an operator, such as an operating surgeon, performs the following operation. 
     The operator, such as an operating surgeon, sets a state where the knife  12 A has protruded from a distal end of the sheath  9 D by the maximum protruding length, by performing a second operation on the slider  82 . In this state, the proximal end of the connector  13 D is separated from the ring portion  9216 , as illustrated in  FIG.  33   . The first hole  922  communicates with the main flow channel M 1  via the pair of third communicating holes  139 . By contrast, the second communicating hole  138  is positioned at the position opposite to the inner surface of the first hole  922 . In this state, the inner surface of the first hole  922  is in contact with the outer peripheral surface (a peripheral edge portion of an opening) of the connector  13 D, and a flow channel between the second communicating hole  138  and the main flow channel M 1  is thereby blocked by the inner peripheral surface of the first hole  922 , as indicated by the marks, “x”, in  FIG.  33   . That is, the inner surface of the first hole  922  corresponds to a first closing portion, the first closing portion being arranged in the sheath  9 D and being capable of closing the opening of the incision portion  11 D, the opening being near the proximal end of the incision portion  11 D. 
     Subsequently, an operator, such as an operating surgeon, causes saline solution to be supplied from the water feeding source  200  by operating an operating unit (not illustrated in the drawings), such as a foot switch, while maintaining the state where the knife  12 A has protruded from the distal end of the sheath  9 D by the maximum protruding length through the second operation on the slider  82 . The saline solution supplied from the water feeding source  200  is thereby discharged from the distal end of the sheath  9 D after following a flow channel through the third communicating holes  139  and the first hole  922 , from the main flow channel M 1 , as indicated by arrows in  FIG.  33   . An opening between an inner peripheral surface of the first hole  922  and an outer peripheral surface of the knife main body  121  has an area larger than that of an opening of the knife hole  123 A. Therefore, the surgical site is irrigated with the saline solution discharged from the distal end of the sheath  9 D (the distal end member  92 D). 
     As described above, in this fifth embodiment, similarly to the above described first embodiment, the main flow channel M 1  is capable of communicating with each of the first hole  922  and the second hole  120 D, near the distal end of the sheath  9 D (the distal end member  92 D). Furthermore, in this configuration, switching between a first mode and a second mode is enabled by advancement and retraction of the incision portion  11 D according to operations on the slider  82  by an operator, such as an operating surgeon. The first mode is set by movement of the incision portion  11 D toward the distal end of the sheath  9 D and is a mode where saline solution is passed to flow into a body cavity by the main flow channel M 1  and the first hole  922  communicating with each other. More specifically, the first mode is a state where the main flow channel M 1  and the first hole  922  are in communication with each other and the opening of the incision portion  11 D is closed by the inner surface of the first hole  922 , the opening being near the proximal end of the incision portion  11 D. The second mode is set by movement of the incision portion  11 D toward a proximal end of the sheath  9 D and is a mode where saline solution is passed to flow into the body cavity by the main flow channel M 1  and the second hole  120 D communicating with each other. More specifically, the second mode is a state where the main flow channel M 1  and the second hole  120 D are in communication with each other and the opening of the first hole  922  is closed by the connector  13 D, the opening being near the proximal end of the first hole  922 . 
     In a case where the treatment tool insertion portion  7 D according to the fifth embodiment described above is adopted also, effects similar to those of the above described first embodiment are achieved. 
     Sixth Embodiment 
     A sixth embodiment will be described next. 
     In the following description, any component that is the same as that of the above described first embodiment will be assigned with the same reference sign, and detailed description thereof will be omitted or simplified. 
     The distal end portion of the treatment tool insertion portion  7  in the endoscope treatment tool  6 , described above with respect to the first embodiment, is differently configured in an endoscope treatment tool  6 , according to the sixth embodiment. For convenience of explanation, a treatment tool insertion portion according to the sixth embodiment will hereinafter be referred to as a treatment tool insertion portion  7 E. 
       FIG.  34    and  FIG.  35    are diagrams illustrating a configuration of the treatment tool insertion portion  7 E according to the sixth embodiment. Specifically,  FIG.  34    is a sectional view corresponding to  FIG.  2   .  FIG.  35    is a sectional view of the treatment tool insertion portion  7 E at a position of a line XXXV-XXXV illustrated in  FIG.  34   . 
     The sheath  9  and the incision portion  11  of the treatment tool insertion portion  7  described above with respect to the first embodiment are differently configured in the treatment tool insertion portion  7 E, as illustrated in  FIG.  34    and  FIG.  35   . For convenience of explanation, a sheath and an incision portion according to the sixth embodiment will hereinafter be referred to as a sheath  9 E and an incision portion  11 E, respectively. 
     As illustrated in  FIG.  34    and  FIG.  35   , the distal end member  92  of the sheath  9  described above with respect to the first embodiment is differently configured in the sheath  9 E. For convenience of explanation, a distal end member according to the sixth embodiment will hereinafter be referred to as a distal end member  92 E. 
     The distal end member  92 E may be formed of a single part or may be formed of a combination of plural parts. 
     As illustrated in  FIG.  34    and  FIG.  35   , the third wall portion  9214  described above with respect to the second embodiment is provided in the distal end member  92 E, instead of the first and second wall portions  9211  and  9212  in the distal end member  92  described above with respect to the first embodiment. 
     As illustrated in  FIG.  34    and  FIG.  35   , the knife  12  and the connector  13  of the incision portion  11  described above with respect to the first embodiment are differently configured in the incision portion  11 E. For convenience of explanation, a knife and a connector according to the sixth embodiment will hereinafter be referred to as a knife  12 E and a connector  13 E, respectively. 
     As illustrated in  FIG.  34   , the knife  12 E has an outer shape that is the same as that of the knife  12 A described above with respect to the second embodiment. That is, the knife  12 E includes a knife main body  121  and a projecting portion  122 A. In this sixth embodiment, the dimension of the outer diameter of the knife main body  121  is set slightly smaller than the dimension of the inner diameter of a ring portion  9216 . The knife main body  121  is inserted in the ring portion  9216 . 
     Furthermore, as illustrated in  FIG.  34   , the knife hole  123 A in the knife  12 A described above with respect to the second embodiment is differently shaped in the knife  12 E. For convenience of explanation, a knife hole according to the sixth embodiment will hereinafter be referred to as a knife hole  123 E. 
     The knife hole  123 E includes a second hole main body  1237  ( FIG.  34   ) and a communicating hole  1238  ( FIG.  34    and  FIG.  35   ). 
     The second hole main body  1237  extends linearly along a central axis of the knife main body  121  from a distal end face of the projecting portion  122 A in a proximal direction, as illustrated in  FIG.  34   . The second hole main body  1237  may preferably be positioned on the central axis of the knife main body  121 . 
     As illustrated in  FIG.  34    and  FIG.  35   , the communicating hole  1238  is a cross-shaped hole that communicates with a proximal end portion of the second hole main body  1237  and is open on an outer peripheral surface of the knife main body  121 . 
     The knife hole  123 E described above is open on an outer peripheral surface of the incision portion  11 E, the outer peripheral surface being near a proximal end of the incision portion  11 E, and corresponds to a second hole  120 E ( FIG.  34   ). 
     The connector  13 E is positioned on a central axis of the distal end member  92 E and is formed of a cylindrical member extending linearly along the central axis. The dimension of the outer diameter of the connector  13 E is set larger than the dimension of the inner diameter of the ring portion  9216 . 
     Operation of an endoscope treatment tool  6 , according to the sixth embodiment, will be described next. For convenience of explanation, a flow of ESD will hereinafter be described as an example, similarly to the above described first embodiment. 
       FIG.  36    and  FIG.  37    are diagrams illustrating the operation of the endoscope treatment tool  6 . Specifically,  FIG.  36    and  FIG.  37    are sectional views corresponding to  FIG.  34   . 
     In this sixth embodiment, an operator, such as an operating surgeon, performs a local injection process as described below. 
     That is, the operator, such as an operating surgeon, sets a state where only the projecting portion  122 A has protruded outside the distal end member  92 E from a first hole  922 , by performing a first operation on the slider  82 . In this state, the communicating hole  1238  is positioned at a position displaced from an inner peripheral surface of the ring portion  9216 , as illustrated in  FIG.  36   . The communicating hole  1238  is thereby in communication with a main flow channel M 1 . By contrast, as indicated by the marks, “x”, in  FIG.  36   , the projecting portion  122 A comes into contact with a distal end of the sheath  9 E (the distal end member  92 E) and the first hole  922  is thus closed near a distal end of the first hole  922  by the projecting portion  122 A. That is, the projecting portion  122 A corresponds to a second closing portion, the second closing portion enabling an opening of the first hole  922  to be closed, the opening being near the distal end of the first hole  922 . 
     Subsequently, an operator, such as an operating surgeon, causes saline solution to be supplied from the water feeding source  200  by operating an operating unit (not illustrated in the drawings), such as a foot switch, while maintaining the state where only the projecting portion  122 A has protruded outside the distal end member  92 E from the first hole  922  through the first operation on the slider  82 , that is, a state where the projecting portion  122 A has protruded from the first hole  922  and the knife main body  121  has been positioned in the first hole  922 . The saline solution supplied from the water feeding source  200  is thereby discharged from a distal end of the knife  12 E after following a flow channel through the communicating hole  1238  and the second hole main body  1237 , from the main flow channel M 1 , as indicted by arrows in  FIG.  36   . The discharged saline solution is injected below a target site T 1  by the force of the current of the saline solution. The target site T 1  then floats up from other tissue, such as a submucosal layer below the target site T 1 . 
     A marking process and an incision process are similar to those of the first embodiment described above, and description thereof will thus be omitted. 
     Furthermore, when performing irrigation of the surgical site in the processes of the ESD, an operator, such as an operating surgeon, performs the following operation. 
     The operator, such as an operating surgeon, sets a state where the knife  12 E has protruded from the distal end of the sheath  9 E by the maximum protruding length, by performing a second operation on the slider  82 . In this state, a distal end of the connector  13 E is in contact with a proximal end face of the ring portion  9216 . Furthermore, as illustrated in  FIG.  37   , the communicating hole  1238  is positioned at a position opposite to the inner peripheral surface of the ring portion  9216 . In this state, the inner peripheral surface of the ring portion  9216  is in contact with the outer peripheral surface (a peripheral edge portion of an opening) of the knife main body  121 , and a flow channel between the communicating hole  1238  and the main flow channel M 1  is thereby blocked by the ring portion  9216  as indicated by the marks, “x”, in  FIG.  37   . That is, the ring portion  9216  corresponds to a first closing portion, the first closing portion being arranged in the sheath  9 E and enabling an opening of the incision portion  11 E to be closed, the opening being near the proximal end of the incision portion  11 E. By contrast, the first hole  922  is released from the closure near the distal end of the first hole  922  by the projecting portion  122 A. 
     Subsequently, an operator, such as an operating surgeon, causes saline solution to be supplied from the water feeding source  200  by operating an operating unit (not illustrated in the drawings), such as a foot switch, while maintaining the state where the knife  12 E has protruded from the distal end of the sheath  9 E by the maximum protruding length through the second operation on the slider  82 . The saline solution supplied from the water feeding source  200  is thereby discharged from the distal end of the sheath  9 E and supplied to the surgical site, after following a flow channel through the first hole  922  from the main flow channel M 1 , as indicated by arrows in  FIG.  37   . An opening between an inner peripheral surface of the first hole  922  and the outer peripheral surface of the knife main body  121  has an area larger than that of an opening of the second hole main body  1237 . Therefore, the surgical site is irrigated with the saline solution discharged from the distal end of the sheath  9 E (the distal end member  92 E). 
     As described above, in this sixth embodiment, similarly to the above described first embodiment, the main flow channel M 1  is capable of communicating with each of the first hole  922  and the second hole  120 E, near the distal end of the sheath  9 E (the distal end member  92 E). Furthermore, in this configuration, switching between a first mode and a second mode is enabled by advancement and retraction of the incision portion  11 E according to operations on the slider  82  by an operator, such as an operating surgeon. The first mode is set by movement of the incision portion  11 E toward a proximal end of the sheath  9 E and is a mode where saline solution is passed to flow into a body cavity by the main flow channel M 1  and the first hole  922  communicating with each other. More specifically, the first mode is a state where the main flow channel M 1  and the first hole  922  are in communication with each other and the opening of the incision portion  11 E is closed by the ring portion  9216 , the opening being near the proximal end of the incision portion  11 E. The second mode is set by movement of the incision portion  11 E toward the proximal end of the sheath  9 E and is a mode where saline solution is passed to flow into the body cavity by the main flow channel M 1  and the second hole  120 E communicating with each other. More specifically, the second mode is a state where the main flow channel M 1  and the second hole  120 E are in communication with each other and the opening of the first hole  922  is closed by the projecting portion  122 A, the opening being near the distal end of the first hole  922 . 
     In a case where the treatment tool insertion portion  7 E according to the sixth embodiment described above is adopted also, effects similar to those of the above described first embodiment are achieved. 
     Seventh Embodiment 
     A seventh embodiment will be described next. 
     In the following description, any component that is the same as that of the above described first embodiment will be assigned with the same reference sign, and detailed description thereof will be omitted or simplified. 
     The distal end portion of the treatment tool insertion portion  7  in the endoscope treatment tool  6 , described above with respect to the first embodiment, is differently configured in an endoscope treatment tool  6 , according to the seventh embodiment. For convenience of explanation, a treatment tool insertion portion according to the seventh embodiment will hereinafter be referred to as a treatment tool insertion portion  7 F. 
       FIG.  38    and  FIG.  39    are diagrams illustrating a configuration of the treatment tool insertion portion  7 F according to the seventh embodiment. Specifically,  FIG.  38    is a sectional view corresponding to  FIG.  2   .  FIG.  39    is a sectional view of the treatment tool insertion portion  7 F at a position of a line XXXIX-XXXIX illustrated in  FIG.  38   . 
     The sheath  9  and the incision portion  11  of the treatment tool insertion portion  7  described above with respect to the first embodiment are differently configured in the treatment tool insertion portion  7 F, as illustrated in  FIG.  38    and  FIG.  39   . For convenience of explanation, a sheath and an incision portion according to the seventh embodiment will hereinafter be referred to as a sheath  9 F and an incision portion  11 F, respectively. 
     As illustrated in  FIG.  38    and  FIG.  39   , the distal end member  92  of the sheath  9  described above with respect to the first embodiment is differently configured in the sheath  9 F. For convenience of explanation, a distal end member according to the seventh embodiment will hereinafter be referred to as a distal end member  92 F. 
     The distal end member  92 F may be formed of a single part or may be formed of a combination of plural parts. 
     As illustrated in  FIG.  38    and  FIG.  39   , a third wall portion  9214 F that is approximately the same as the third wall portion  9214  described above with respect to the second embodiment is provided in the distal end member  92 F, instead of the first and second wall portions  9211  and  9212  in the distal end member  92  described above with respect to the first embodiment. 
     The inner peripheral surface of the ring portion  9216  of the third wall portion  9214  described above with respect to the second embodiment is differently shaped in the third wall portion  9214 , as illustrated in  FIG.  38    and  FIG.  39   . For convenience of explanation, a ring portion according to the seventh embodiment will hereinafter be referred to as a ring portion  9216 F. 
     An inner peripheral surface of the ring portion  9216 F has a truncated cone shape that decreases in inner diameter toward a distal end thereof, as illustrated in  FIG.  38    and  FIG.  39   . 
     As illustrated in  FIG.  38    to  FIG.  39   , the knife  12 A described above with respect to the second embodiment is adopted in the incision portion  11 F, instead of the knife  12  in the incision portion  11  described above with respect to the first embodiment, and the connector  13  in the incision portion  11  is also shaped differently in the incision portion  11 F. For convenience of explanation, a connector according to the seventh embodiment will hereinafter be referred to as a connector  13 F. 
     The connector  13 F extends along a central axis of the distal end member  92 F and has a truncated cone shape that is approximately the same as that of the inner peripheral surface of the ring portion  9216 F. Furthermore, first and second communicating holes  130 F 1  and  130 F 2  are provided in the connector  13 F, as illustrated in  FIG.  38    and  FIG.  39   . The connector  13 F may preferably be positioned on the central axis of the distal end member  92 F. 
     The first communicating hole  130 F 1  extends linearly along a central axis of the connector  13 F from a distal end to a proximal end of the connector  13 F, as illustrated in  FIG.  38   . In a state where the connector  13 F and a knife main body  121  have been connected to each other, the first communicating hole  130 F 1  is in communication with a knife hole  123 A. The first communicating hole  130 F 1  may preferably be positioned on the central axis of the connector  13 F. 
     As illustrated in  FIG.  38    and  FIG.  39   , the second communicating hole  130 F 2  is a cross-shaped hole that is positioned at an approximately central portion of the longitudinal length of the connector  13 F, communicates with the first communicating hole  130 F 1 , and is open on an outer peripheral surface of the connector  13 F. 
     The knife hole  123 A and first and second communicating holes  130 F 1  and  130 F 2  described above are open on an outer peripheral surface of the incision portion  11 F, the outer peripheral surface being close to a proximal end of the incision portion  11 F, and correspond to a second hole  120 F ( FIG.  38   ). 
     Operation of an endoscope treatment tool  6 , according to the seventh embodiment, will be described next. For convenience of explanation, a flow of ESD will hereinafter be described as an example, similarly to the above described first embodiment. 
       FIG.  40    and  FIG.  41    are diagrams illustrating the operation of the endoscope treatment tool  6 . Specifically,  FIG.  40    and  FIG.  41    are sectional views corresponding to  FIG.  38   . 
     In this seventh embodiment, an operator, such as an operating surgeon, performs a local injection process as described below. 
     That is, the operator, such as an operating surgeon, sets a state where only a projecting portion  122 A has protruded outside the distal end member  92 F from a first hole  922 , by performing a first operation on the slider  82 . In this state, the connector  13 F is positioned at a position separated in a proximal direction from the inner peripheral surface of the ring portion  9216 F, as illustrated in  FIG.  40   . The second communicating hole  130 F 2  is thereby in communication with a main flow channel M 1 . By contrast, as indicated by the marks, “x”, in  FIG.  40   , the projecting portion  122 A is in contact with a distal end of the sheath  9 F (the distal end member  92 F) and the first hole  922  is thus closed near a distal end of the first hole  922  by the projecting portion  122 A. That is, the projecting portion  122 A corresponds to a second closing portion, the second closing portion enabling an opening of the first hole  922  to be closed, the opening being near the distal end of the first hole  922 . 
     Subsequently, an operator, such as an operating surgeon, causes saline solution to be supplied from the water feeding source  200 , by operating an operating unit (not illustrated in the drawings), such as a foot switch, while maintaining the state where only the projecting portion  122 A has protruded outside the distal end member  92 F from the first hole  922  through the first operation on the slider  82 . The saline solution supplied from the water feeding source  200  is thereby discharged from a distal end of the knife  12 A after following a flow channel through the second communicating hole  130 F 2 , the first communicating hole  130 F 1 , and the knife hole  123 A, from the main flow channel M 1 , as indicated by arrows in  FIG.  40   . The discharged saline solution is injected below a target site T 1  by the force of the current of the saline solution. The target site T 1  then floats up from other tissue, such as a submucosal layer below the target site T 1 . 
     A marking process and an incision process are similar to those of the first embodiment described above, and description thereof will thus be omitted. 
     Furthermore, when performing irrigation of the surgical site in the processes of the ESD, an operator, such as an operating surgeon, performs the following operation. 
     The operator, such as an operating surgeon, sets a state where the knife  12 A has protruded from the distal end of the sheath  9 F by the maximum protruding length, by performing a second operation on the slider  82 . In this state, as illustrated in  FIG.  41   , the connector  13 F is in contact with the inner peripheral surface of the ring portion  9216 F. In this state, the inner peripheral surface of the ring portion  9216 F is in contact with the outer peripheral surface (a peripheral edge portion of an opening) of the connector  13 F, and a flow channel between the second communicating hole  130 F 2  and the main flow channel M 1  is blocked by the ring portion  9216 F as indicated by the marks, “x”, in  FIG.  41   . That is, the ring portion  9216 F corresponds to a first closing portion, the first closing portion being arranged in the sheath  9 F and enabling the opening of the incision portion  11 F to be closed, the opening being near the proximal end of the incision portion  11 F. By contrast, the first hole  922  is released from the closure near the distal end of the first hole  922  by the projecting portion  122 A. 
     Subsequently, an operator, such as an operating surgeon, causes saline solution to be supplied from the water feeding source  200  by operating an operating unit (not illustrated in the drawings), such as a foot switch, while maintaining the state where the knife  12 A has protruded from the distal end of the sheath  9 F by the maximum protruding length through the second operation on the slider  82 . The saline solution supplied from the water feeding source  200  is thereby discharged from the distal end of the sheath  9 F and supplied to the surgical site, after following a flow channel through the first hole  922  from the main flow channel M 1 , as indicated by arrows in  FIG.  41   . An opening between an inner peripheral surface of the first hole  922  and an outer peripheral surface of the knife main body  121  has an area larger than that of an opening of the knife hole  123 A. Therefore, the surgical site is irrigated with the saline solution discharged from the distal end of the sheath  9 F (the distal end member  92 F). 
     As described above, in this seventh embodiment, similarly to the above described first embodiment, the main flow channel M 1  is capable of communicating with each of the first hole  922  and the second hole  120 F, near the distal end of the sheath  9 F (the distal end member  92 F). Furthermore, in this configuration, switching between a first mode and a second mode is enabled by advancement and retraction of the incision portion  11 F according to operations on the slider  82  by an operator, such as an operating surgeon. The first mode is set by movement of the incision portion  11 F toward the distal end of the sheath  9 F and is a mode where saline solution is passed to flow into a body cavity by the main flow channel M 1  and the first hole  922  communicating with each other. More specifically, the first mode is a state where the main flow channel M 1  and the first hole  922  are in communication with each other and the opening of the incision portion  11 F is closed by the ring portion  9216 F, the opening being near the proximal end of the incision portion  11 F. The second mode is set by movement of the incision portion  11 F toward a proximal end of the sheath  9 F and is a mode where saline solution is passed to flow into the body cavity by the main flow channel M 1  and the second hole  120 F communicating with each other. More specifically, the second mode is a state where the main flow channel M 1  and the second hole  120 F are in communication with each other and the opening of the first hole  922  is closed by the projecting portion  122 A, the opening being near the distal end of the first hole  922 . 
     In a case where the treatment tool insertion portion  7 F according to the seventh embodiment described above is adopted also, effects similar to those of the above described first embodiment are achieved. 
     In particular, the inner peripheral surface of the ring portion  9216  and the connector  13 F have the truncated cone shapes and saline solution is thus prevented from leaking into the second hole  120 F in the first mode. 
     Eighth Embodiment 
     An eighth embodiment will be described next. 
     In the following description, any component that is the same as that of the above described first embodiment will be assigned with the same reference sign, and detailed description thereof will be omitted or simplified. 
     The distal end portion of the treatment tool insertion portion  7  in the endoscope treatment tool  6 , described above with respect to the first embodiment, is differently configured in an endoscope treatment tool  6 , according to the eighth embodiment. For convenience of explanation, a treatment tool insertion portion according to the eighth embodiment will hereinafter be referred to as a treatment tool insertion portion  7 G. 
       FIG.  42    and  FIG.  43    are diagrams illustrating a configuration of the treatment tool insertion portion  7 G according to the eighth embodiment. Specifically,  FIG.  42    is a sectional view corresponding to  FIG.  2   .  FIG.  43    is a sectional view of the treatment tool insertion portion  7 G at a position of a line XXXXIII-XXXXIII illustrated in  FIG.  42   . 
     As illustrated in  FIG.  42    and  FIG.  43   , the wire  10 B described above with respect to the third embodiment is adopted in the treatment tool insertion portion  7 G, instead of the wire  10  in the treatment tool insertion portion  7  described above with respect to the first embodiment, and the sheath  9  and the incision portion  11  in the treatment tool insertion portion  7  are also differently configured in the treatment tool insertion portion  7 G. For convenience of explanation, a sheath and an incision portion according to the eighth embodiment will hereinafter be referred to as a sheath  9 G and an incision portion  11 G, respectively. 
     As illustrated in  FIG.  42    and  FIG.  43   , the distal end member  92  of the sheath  9  described above with respect to the first embodiment is differently shaped in the sheath  9 G. For convenience of explanation, a distal end member according to the eighth embodiment will hereinafter be referred to as a distal end member  92 G. 
     The distal end member  92 G may be formed of a single part or may be formed of a combination of plural parts. 
     As illustrated in  FIG.  42   , the first and second wall portions  9211  and  9212  of the distal end member  92  described above with respect to the first embodiment are omitted from the distal end member  92 G. 
     Furthermore, as illustrated in  FIG.  42   , the first hole  922  in the distal end member  92  described above with respect to the first embodiment is differently shaped in the distal end member  92 G. For convenience of explanation, a first hole according to the eighth embodiment will hereinafter be referred to as a first hole  922 G. 
     The first hole  922 G includes a hole main body  922 G 1  and an auxiliary hole  922 G 2 , as illustrated in  FIG.  42   . 
     The hole main body  922 G 1  has a circular cross-section and extends linearly along a central axis of the distal end member  92 G. The dimension of the inner diameter of the hole main body  922 G 1  is set smaller than the dimension of the outer diameter of a projecting portion  122 A and larger than the dimension of the outer diameter of a knife main body  121 . The hole main body  922 G 1  may preferably be positioned on the central axis of the distal end member  92 G. 
     As illustrated in  FIG.  42   , the auxiliary hole  922 G 2  is a portion extending in a radial direction from a part of the hole main body  922 G 1 , and extends linearly along the central axis of the distal end member  92 G, similarly to the hole main body  922 G 1 . 
     As illustrated in  FIG.  42    and  FIG.  43   , the knife  12 A described above with respect to the second embodiment is adopted in the incision portion  11 G, instead of the knife  12  in the incision portion  11  described above with respect to the first embodiment, and the connector  13  in the incision portion  11  is also shaped differently in the incision portion  11 G. For convenience of explanation, a connector according to the eighth embodiment will hereinafter be referred to as a connector  13 G. 
     The connector  13 G is formed of a cylindrical member extending linearly along the central axis of the distal end member  92 G. The dimension of the outer diameter of the connector  13 G is set larger than the dimension of the inner diameter of the hole main body  922 G 1  and smaller than the dimension of the inner diameter of the distal end member  92 G. Furthermore, as illustrated in  FIG.  42    and  FIG.  43   , first and second fitting holes  130 G 1  and  130 G 2 , a receiving hole  130 G 3 , and a communicating hole  130 G 4  are provided in the connector  13 G. The connector  13 G may preferably be positioned on the central axis of the distal end member  92 G. 
     The first fitting hole  130 G 1  is a circular hole extending linearly along a central axis of the connector  13 G from a distal end of the connector  13 G toward a proximal end of the connector  13 G. The knife main body  121  is fixed in a state of being inserted in the first fitting hole  130 G 1 . The first fitting hole  130 G 1  may preferably be positioned on the central axis of the connector  13 G. 
     The second fitting hole  130 G 2  is a circular hole extending linearly along the central axis of the connector  13 G from the proximal end of the connector  13 G toward the distal end of the connector  13 G. The wire  10 B is fixed in a state of being inserted in the second fitting hole  130 G 2 . The second fitting hole  130 G 2  may preferably be positioned on the central axis of the connector  13 G. 
     The receiving hole  130 G 3  is a circular hole extending linearly along the central axis of the connector  13 G from near the distal end of the connector  13 G toward the proximal end of the connector  13 G, and communicates with the first and second fitting holes  130 G 1  and  130 G 2 . The dimension of the inner diameter of the receiving hole  130 G 3  is set larger than the dimensions of the inner diameters of the first and second fitting holes  130 G 1  and  130 G 2 . In a state where the knife  12 A and the wire  10 B have been connected to each other by the connector  13 G, a main flow channel M 1  is in communication with a knife hole  123 A via the receiving hole  130 G 3 . That is, the knife hole  123 A and the receiving hole  130 G 3  correspond to a second hole  120 G ( FIG.  42   ). The receiving hole  130 G 3  may preferably be positioned on the central axis of the connector  13 G. 
     The communicating hole  130 G 4  is an elongated hole penetrating the connector  13 G from an outer peripheral surface of the connector  13 G to the receiving hole  130 G 3  and extending along a longitudinal axis of the connector  13 G. 
     In this eighth embodiment, a biasing member  14  and a flow channel switching member  15  are attached to the above described connector  13 G, as illustrated in  FIG.  42    and  FIG.  43   . 
     As illustrated in  FIG.  42    and  FIG.  43   , the biasing member  14  is formed of a coil spring and arranged in the receiving hole  130 G 3 . One end of the biasing member  14  is brought into contact with or fixed to a supporting portion  151  included in the flow channel switching member  15  and the other end of the biasing member  14  is brought into contact with or fixed to a peripheral edge portion of the second fitting hole  130 G 2 . The biasing member  14  biases the flow channel switching member  15  in a distal direction. 
     The flow channel switching member  15  is a member that switches between flow channels for saline solution passed via the main flow channel M 1 . This flow channel switching member  15  includes the supporting portion  151  and a closing portion  152 , as illustrated in  FIG.  42    and  FIG.  43   . 
     The supporting portion  151  is inserted in the receiving hole  130 G 3  through the communicating hole  130 G 4 , is orthogonal to the central axis of the connector  13 G, and has a shape of a pin arranged in a posture positioned on the central axis of the connector  13 G. 
     The closing portion  152  is fixed to an end portion of the supporting portion  151 , the end portion being positioned outside the connector  13 G, and has a plate shape extending along the central axis of the connector  13 G. The size of this closing portion  152  is set to enable the communicating hole  130 G 4  to be closed. 
     Operation of the endoscope treatment tool  6 , according to the eighth embodiment, will be described next. For convenience of explanation, a flow of ESD will hereinafter be described as an example, similarly to the above described first embodiment. 
       FIG.  44    and  FIG.  45    are diagrams illustrating the operation of the endoscope treatment tool  6 . Specifically,  FIG.  44    and  FIG.  45    are sectional views corresponding to  FIG.  42   . 
     In this eighth embodiment, an operator, such as an operating surgeon, performs a local injection process as described below. 
     That is, the operator, such as an operating surgeon, sets a state where only the projecting portion  122 A has protruded outside the distal end member  92 G from the first hole  922 G, by performing a first operation on the slider  82 . In this state, the connector  13 G is in a state of being positioned in a proximal direction from the distal end member  92 G, as illustrated in  FIG.  44   . Furthermore, the flow channel switching member  15  moves in the distal direction relatively to the connector  13 G, due to biasing force of the biasing member  14 . In this state, the closing portion  152  is in contact with the outer peripheral surface (a peripheral edge portion of an opening) of the connector  13 G and the communicating hole  130 G 4  is thereby closed by the closing portion  152 . 
     Subsequently, an operator, such as an operating surgeon, causes saline solution to be supplied from the water feeding source  200 , by operating an operating unit (not illustrated in the drawings), such as a foot switch, while maintaining the state where only the projecting portion  122 A has protruded outside the distal end member  92 G from the first hole  922 G through the first operation on the slider  82 . The saline solution supplied from the water feeding source  200  is thereby discharged from a distal end of the knife  12 A after following a flow channel through the receiving hole  130 G 3  and the knife hole  123 A, from the main flow channel M 1 , as indicated by arrows in  FIG.  44   . The discharged saline solution is injected below a target site T 1  by the force of the current of the saline solution. The target site T 1  then floats up from other tissue, such as a submucosal layer below the target site T 1 . 
     A marking process and an incision process are similar to those of the first embodiment described above, and description thereof will thus be omitted. 
     Furthermore, when performing irrigation of the surgical site in the processes of the ESD, an operator, such as an operating surgeon, performs the following operation. 
     The operator, such as an operating surgeon, sets a state where the knife  12 A has protruded from a distal end of the sheath  9 G by the maximum protruding length, by performing a second operation on the slider  82 . During the course of the second operation, the connector  13 G advances into the distal end member  92 G from the proximal direction. By contrast, the flow channel switching member  15  gets caught on a proximal end of the distal end member  92 G and moves in the proximal direction relatively to the connector  13 G against the biasing force of the biasing member  14 . The communicating hole  130 G 4  is thereby released from the closure by the closing portion  152 , as illustrated in  FIG.  45   . 
     Subsequently, an operator, such as an operating surgeon, causes saline solution to be supplied from the water feeding source  200  by operating an operating unit (not illustrated in the drawings), such as a foot switch, while maintaining the state where the knife  12 A has protruded from the distal end of the sheath  9 G by the maximum protruding length through the second operation on the slider  82 . The saline solution supplied from the water feeding source  200  is thereby supplied to the surgical site by being: discharged from the distal end of the knife  12 A after following the flow channel through the receiving hole  130 G 3  and the knife hole  123 A from the main flow channel M 1 ; and discharged from the distal end of the sheath  9 G after following a flow channel through the receiving hole  130 G 3 , the communicating hole  130 G 4 , the distal end member  92 G, and the auxiliary hole  922 G 2 , from the main flow channel M 1 . The saline solution that has followed the main flow channel M 1  is thus discharged from both the knife hole  123 A and the auxiliary hole  922 G 2 . Therefore, the surgical site is irrigated with the saline solution discharged from both the knife hole  123 A and the auxiliary hole  922 G 2 . 
     As described above, similarly to the above described first embodiment, in this eighth embodiment also, the main flow channel M 1  is capable of communicating with each of the first hole  922 G and the second hole  120 G, near the distal end of the sheath  9 G (the distal end member  92 G). Furthermore, in this configuration, switching between a first mode and a second mode is enabled by advancement and retraction of the incision portion  11 G according to operations on the slider  82  by an operator, such as an operating surgeon. The first mode is a mode where the main flow channel M 1  is in communication with the first hole  922 G and second hole  120 G and saline solution is thereby passed to flow into a body cavity. The second mode is a mode where the main flow channel M 1  is in communication with the second hole  120 G and the saline solution is thereby passed to flow into the body cavity. 
     In a case where the treatment tool insertion portion  7 G according to the eighth embodiment described above is adopted also, effects similar to those of the above described first embodiment are achieved. 
     Other Embodiments 
     Modes for implementing the disclosure have been described thus far, but the disclosure is not to be limited only to the above described first to eighth embodiments. 
     In the above described first to eighth embodiments, the surgical site is irrigated in the first mode and the local injection process is executed in the second mode, but the disclosure is not limited to these embodiments. For example, the surgical site may be irrigated in both the first and second modes. 
     In all of the first to eighth embodiments described above, the rotating restricting structure (the second wall portion  9212  (the groove portion  9213 ) and the rotation restricting portion  132 ) according to the disclosure may be adopted. 
     In the above described first to eighth embodiments, the projecting portion  122  ( 122 A) is not limited to the shape described above with respect to the first to eighth embodiments, and any other shape may be adopted. 
       FIG.  46 A  and  FIG.  46 B  are diagrams illustrating examples of the shape of the projecting portion  122  ( 122 A). 
     Specifically, as illustrated in  FIG.  46 A  or  FIG.  46 B , the projecting portion  122  ( 122 A) may have a flange shape that is, for example, semispherical ( FIG.  46 A ) or triangular ( FIG.  46 B ), or may have a needle shape without being flanged. 
     An endoscope treatment tool, according to the disclosure, enables improvement of user-friendliness. 
     Additional advantages and modifications will readily occur to those skilled in the art. Therefore, the disclosure in its broader aspects is not limited to the specific details and representative embodiments shown and described herein. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.