Abstract:
This endoscopic surgical device includes: an endoscope; a treatment tool; and a mantle tube. The inside of the mantle tube is partitioned by a partition wall member provided with an endoscope guide groove and a treatment-tool guide groove, to form an endoscope insertion passage and a treatment-tool insertion passage. An endoscope fixation tool and a treatment-tool fixation tool are respectively disposed inside the endoscope guide groove and the treatment-tool guide groove. The endoscope fixation tool advances and retracts in conjunction with the endoscope insertion part inserted through the endoscope insertion passage. The treatment-tool fixation tool moves in conjunction with the treatment-tool insertion part inserted through the treatment-tool insertion passage. When a coupling ring externally fitted to the partition wall member interlocks the endoscope fixation tool with the treatment-tool fixation tool, the endoscope insertion part also moves in conjunction with the advancement and retraction of the treatment-tool insertion part.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a Continuation of PCT International Application No. PCT/JP2016/058010 filed on Mar. 14, 2016, which claims priority under 35 U.S.C. §119(a) to U.S. Provisional Application No. 62/136,865 filed on Mar. 23, 2015. Each of the above applications is hereby expressly incorporated by reference, in their entirety, into the present application. 
     
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
       [0002]    The present invention relates to an endoscopic surgical device and an overtube, and particularly, relates to an endoscopic surgical device and an overtube that can operate an endoscope and a treatment tool inserted through two insertion passages provided in an overtube in an interlocking manner. 
       2. Description of the Related Art 
       [0003]    In recent years, since invasion to a patient is small compared to surgery in which a laparotomy, a thoracotomy, or the like is performed, endoscopic surgery using endoscopes (hard endoscopes), such as a laparoscope, is widely performed. In the endoscopic surgery, a plurality of holes are made in a patient&#39;s body wall, an endoscope is inserted into a body cavity from one hole of them, and a treatment tool is inserted into the body cavity from another hole. Then, treatment of living body tissue is performed with the treatment tool while observing the living body tissue within the body cavity with the endoscope. 
         [0004]    Generally, in the endoscopic surgery, one or a plurality of treatment tools are used simultaneously with the endoscope. Therefore, since it is difficult for one operator to simultaneously operate the endoscope and the plurality of treatment tools, for example, a task of operating treatment tools using both hands by the operator while making an assistant called an endoscopic technician operate the endoscope is normally performed. 
         [0005]    In this way, in the endoscopic surgery, it is general that the operator&#39;s hands are bound by the operation of the treatment tool, and the operation of the endoscope is performed by the assistant. Therefore, in a case where the observation position of the endoscope is changed, the operator should serially give instructions to the assistant. Hence, the task of correctly directing the orientation of the endoscope to a direction desired by the operator is difficult, and stress is likely to be imposed on the operator. Additionally, since the assistant performs an operation after the operator issues an instruction, there is a tendency that surgery time is likely to be prolonged. Additionally, the assistant should operate the endoscope so as not to interfere with an operator&#39;s procedure, and the operation is likely to become complicated. 
         [0006]    In contrast, the applicant of the present application suggests a technique in which an endoscope and a treatment tool are combined together by an overtube, and if the treatment tool is moved forward and backward, the endoscope is also moved forward and backward in an interlocking manner with this movement of the treatment tool (refer to WO2013/176167A). Specifically, the overtube that guides an insertion part of the endoscope and an insertion part of the treatment tool into a body cavity includes a tubular overtube body that has an endoscope insertion passage and a treatment tool insertion passage through which the insertion part of the endoscope and the insertion part of the treatment tool are inserted, respectively. 
         [0007]    A coupling mechanism, which has coupling parts that are respectively coupled to the insertion part of the endoscope and the insertion part of the treatment tool and which is movable forward and backward in an axial direction, is provided inside the overtube body. If the insertion part of the treatment tool is moved forward and backward in the axial direction by the coupling mechanism, the insertion part of the endoscope also moves forward and backward in the axial direction in an interlocking manner with this. 
         [0008]    By virtue of such an overtube, the number of holes made in the patient&#39;s body wall can be reduced, the invasion to the patient can be suppressed, and the visual field of the endoscope can be easily changed while an operator operates the treatment tool without asking for an assistant&#39;s help. 
       SUMMARY OF THE INVENTION 
       [0009]    Meanwhile, in the technique suggested in WO2013/176167A by the applicant of the present application, the above coupling mechanism is disposed inside the overtube body, and a constituent member of the coupling mechanism which integrally moves forward and backward reaches the endoscope insertion passage, the treatment tool insertion passage, and a region between these insertion passages. Therefore, no partition wall member is provided between the endoscope insertion passage and the treatment tool insertion passage. 
         [0010]    For that reason, in a case where the endoscope or the treatment tool is inserted through the overtube body, it is necessary to pay attention so that these endoscope and treatment tool do not proceed to any regions other than their original insertion passages inside the overtube body. For that reason, there is a problem that the task of coupling the endoscope or the treatment tool to the coupling mechanism to insert the endoscope or the treatment tool through the overtube requires time and effort. 
         [0011]    The invention has been made in view of such circumstances, and an object thereof is to provide an endoscopic surgical device capable of easily inserting medical instruments through an overtube, and the overtube. 
         [0012]    In order to achieve the above object, an endoscopic surgical device according to an aspect of the invention is an endoscopic surgical device comprising a first medical instrument having a first insertion part inserted into a body cavity; a second medical instrument having a second insertion part inserted into the body cavity; and an overtube that passes through a body wall, is inserted into the body cavity, and guides the first insertion part and the second insertion part into the body cavity. The overtube includes an overtube body having a distal end, a proximal end, and a longitudinal axis, a first distal end opening and a second distal end opening provided at a distal end of the overtube body, a first proximal end opening and a second proximal end opening provided at a proximal end of the overtube body, a first insertion passage that is provided along the longitudinal axis of the overtube body, allows the first distal end opening and the first proximal end opening to communicate with each other, and allows the first insertion part to be inserted therethrough so as to be movable forward and backward, a second insertion passage that is provided along the longitudinal axis of the overtube body, allows the second distal end opening and the second proximal end opening to communicate with each other, and allows the second insertion part to be inserted therethrough so as to be movable forward and backward, and a coupling mechanism that has a first coupling part coupled to the first insertion part inserted through the first insertion passage and a second coupling part coupled to the second insertion part inserted through the second insertion passage. The coupling mechanism includes a partition wall member that is housed inside the overtube body and extends along the longitudinal axis and that has a partition wall between the first insertion passage and the second insertion passage, a first fixing tool that has the first coupling part and is movable forward and backward along the first insertion passage, a second fixing tool that has the second coupling part and is movable forward and backward along the second insertion passage, and a ring-shaped driving member that is externally fitted to an outer peripheral part of the partition wall member and is movable forward and backward along the longitudinal axis with respect to the partition wall member and that has a sensing region where either the first fixing tool or the second fixing tool is moved forward and backward in an interlocking manner with the forward and backward movement of the other of the first fixing tool and the second fixing tool. 
         [0013]    According to this aspect, since the partition wall member having the a partition wall between the first insertion passage and the second insertion passage is included as the coupling mechanism, in a case where the first medical instrument or the second medical instrument is inserted through the first insertion passage or the second insertion passage, the medical instruments can be restrained from proceeding to regions other than the respective insertion passages. 
         [0014]    Accordingly, if an operator inserts the first medical instrument and the second medical instrument into the overtube, the medical instruments reliably proceed to their corresponding insertion passages and are reliably coupled to their corresponding fixing tools. Hence, the task of inserting the medical instruments into the overtube becomes easy. 
         [0015]    In the endoscopic surgical device according to another aspect of the invention, it is possible to adopt an aspect in which the driving member further has a non-sensing region where either the first fixing tool or the second fixing tool is not moved forward and backward in an interlocking manner with the forward and backward movement of the other of the first fixing tool and the second fixing tool. 
         [0016]    According to this aspect, the non-sensing region where either the first medical instrument or the second medical instrument is not moved forward and backward with the forward and backward movement of the other of the first medical instrument and the second medical instrument in the axial direction. 
         [0017]    In the endoscopic surgical device according to still another aspect of the invention, it is possible to adopt an aspect in which the driving member has a first engaging part engaged with the first fixing tool and a second engaging part engaged with the second fixing tool, the first engaging part has a first restricting part that restricts the forward and backward movement of the first fixing tool in a first range, and the second engaging part has a second restricting part that restricts the forward and backward movement of the second fixing tool in a second range different from the first range. 
         [0018]    According to the present aspect, both of the first fixing tool and the second fixing tool are configured separately from the driving member. Also, the first fixing tool and the second fixing tool are respectively engaged with the first engaging part and the second engaging part of the driving member, and the movement range where the forward and backward movement is possible with respect to the driving member is restricted by the engaging parts. 
         [0019]    In the endoscopic surgical device according to a still further aspect of the invention, it is possible to adopt an aspect in which the driving member has a first engaging part engaged with the first fixing tool and a second engaging part engaged with the second fixing tool, and at least one of the first engaging part or the second engaging part allows the movement of a corresponding fixing tool in a direction along with the longitudinal axis. 
         [0020]    According to the present aspect, both of the first fixing tool and the second fixing tool are configured separately from the driving member. Also, the first fixing tool and the second fixing tool are respectively engaged with the first engaging part and the second engaging part of the driving member, and the movement range where the forward and backward movement is possible with respect to the driving member is restricted by the engaging parts. This aspect has the movement range where the forward and backward movement of at least one of the first fixing tool and the second fixing tool with respect to the driving member is allowed. 
         [0021]    In the endoscopic surgical device according to a still further aspect of the invention, it is possible to adopt an aspect in which the driving member has a first engaging part engaged with the first fixing tool and a second engaging part engaged with the second fixing tool, and at least one of the first engaging part or the second engaging part allows the rotation of a corresponding fixing tool in a direction around an axis. 
         [0022]    According to the present aspect, both of the first fixing tool and the second fixing tool are configured separately from the driving member. Also, the first fixing tool and the second fixing tool are respectively engaged with the first engaging part and the second engaging part of the driving member, and the movement range where forward and backward movement is possible with respect to the driving member is restricted by the engaging parts. In this aspect, at least one of the first fixing tool and the second fixing tool moves in the circumferential direction. 
         [0023]    In the endoscopic surgical device according to a still further aspect of the invention, it is possible to adopt an aspect in which the partition wall member has a first guide groove that constitutes a portion of the first insertion passage, and a second guide groove that constitutes a portion of the second insertion passage. 
         [0024]    In the endoscopic surgical device according to a still further aspect of the invention, it is possible to adopt an aspect in which the first insertion passage and the second insertion passage are disposed parallel to each other. 
         [0025]    In the endoscopic surgical device according to a still further aspect of the invention, it is possible to adopt an aspect in which the first insertion passage and the second insertion passage are disposed to obliquely intersect each other. 
         [0026]    In the endoscopic surgical device related to a still further aspect of the invention, it is possible to adopt an aspect in which the first medical instrument is an endoscope in which an observation part is provided at a distal end of the first insertion part, and the second medical instrument is a treatment tool in which a treatment part is provided at a distal end of the second insertion part. 
         [0027]    In the endoscopic surgical device related to a still further aspect of the invention, it is possible to adopt an aspect in which the first medical instrument is an endoscope in which an observation part is provided at a distal end of the first insertion part, the second medical instrument is a treatment tool in which a treatment part is provided at a distal end of the second insertion part, the first insertion passage is disposed to obliquely intersect the longitudinal axis of the overtube body, and the second insertion passage is disposed parallel to the longitudinal axis of the overtube body. 
         [0028]    An overtube according to an aspect of the invention is an overtube comprising an overtube body having a distal end, a proximal end, and a longitudinal axis; a first distal end opening and a second distal end opening provided at a distal end of the overtube body; a first proximal end opening and a second proximal end opening provided at a proximal end of the overtube body, a first insertion passage that is provided along the longitudinal axis of the overtube body, allows the first distal end opening and the first proximal end opening to communicate with each other, and allows a first insertion part of a first medical instrument to be inserted therethrough so as to be movable forward and backward; a second insertion passage that is provided along the longitudinal axis of the overtube body, allows the second distal end opening and the second proximal end opening to communicate with each other, and allows a second insertion part of a second medical instrument to be inserted therethrough so as to be movable forward and backward; and a coupling mechanism that has a first coupling part coupled to the first insertion part inserted through the first insertion passage and a second coupling part coupled to the second insertion part inserted through the second insertion passage. The coupling mechanism includes a partition wall member that is housed inside the overtube body and extends along the longitudinal axis and that has a partition wall between the first insertion passage and the second insertion passage, a first fixing tool that has the first coupling part and is movable forward and backward along the first insertion passage, a second fixing tool that has the second coupling part and is movable forward and backward along the second insertion passage, and a ring-shaped driving member that is externally fitted to an outer peripheral part of the partition wall member and is movable forward and backward along the longitudinal axis with respect to the partition wall member and that has a sensing region where either the first fixing tool or the second fixing tool is moved forward and backward in an interlocking manner with the forward and backward movement of the other of the first fixing tool and the second fixing tool. 
         [0029]    According to this aspect, since the partition wall member having the partition wall between the first insertion passage and the second insertion passage is included as the coupling mechanism, in a case where the first medical instrument or the second medical instrument is inserted through the first insertion passage or the second insertion passage, the medical instruments can be restrained from proceeding to regions other than the respective insertion passages. 
         [0030]    Accordingly, the first medical instrument reliably proceeds through the first insertion passage, the second medical instrument reliably proceeds through the second insertion passage, and these medical instruments are also reliably coupled to the coupling mechanism and inserted through the overtube. Hence, the task of inserting the medical instruments into the overtube becomes easy. 
         [0031]    According to the invention, the medical instruments can be easily inserted through the overtube. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0032]      FIG. 1  is a schematic block diagram of an endoscopic surgical device according to the invention. 
           [0033]      FIG. 2  is a plan view illustrating a distal end surface of the endoscope insertion part. 
           [0034]      FIG. 3  is a perspective view illustrating a state where a sheathing tube is fitted to the overtube. 
           [0035]      FIG. 4  is an external perspective view illustrating the overtube. 
           [0036]      FIG. 5  is a horizontal cross-sectional view illustrating the internal structure of the overtube. 
           [0037]      FIG. 6  is an enlarged view of a portion where the slider is disposed in  FIG. 5 . 
           [0038]      FIG. 7  is a perspective view illustrating the overtube with a long tubular body in a long tubular overtube part omitted. 
           [0039]      FIG. 8  is a perspective view illustrating the overtube with the long tubular body in the long tubular overtube part omitted. 
           [0040]      FIG. 9  is a perspective view illustrating only a partition wall member. 
           [0041]      FIG. 10  is a perspective view illustrating only a coupling ring. 
           [0042]      FIG. 11  is a cross-sectional view when viewed from arrow A-A in  FIG. 6 . 
           [0043]      FIG. 12  is a perspective view illustrating a portion of the overtube in the state of  FIG. 7 . 
           [0044]      FIG. 13  is a perspective view illustrating the overtube of  FIG. 12  with the coupling ring omitted. 
           [0045]      FIG. 14  is a perspective view illustrating the overtube of  FIG. 13  from a right side. 
           [0046]      FIG. 15  is an explanatory view illustrating a state of the operation in a case where the diseased site within the patient&#39;s body cavity is treated using the endoscopic surgical device. 
           [0047]      FIG. 16  is an explanatory view illustrating a state of the operation in a case where the diseased site within the patient&#39;s body cavity is treated using the endoscopic surgical device. 
           [0048]      FIG. 17  is a cross-sectional view illustrating one state of a slider. 
           [0049]      FIG. 18  is a cross-sectional view illustrating one state of the slider. 
           [0050]      FIG. 19  is a cross-sectional view illustrating one state of the slider. 
           [0051]      FIG. 20  is an external perspective view in another embodiment of the overtube. 
           [0052]      FIG. 21  is a perspective view illustrating the overtube of  FIG. 20  with the long tubular body of the long tubular overtube part omitted. 
           [0053]      FIG. 22  is a perspective view illustrating the overtube of  FIG. 20  with the long tubular body of the long tubular overtube part omitted. 
           [0054]      FIG. 23  is a perspective view illustrating a portion of the overtube of  FIG. 20 . 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0055]    Preferred embodiments of the invention will be described below in detail according to the accompanying drawings. In addition, any of the drawings may illustrate main parts in an exaggerated manner for description, and may have dimensions different from actual dimensions. 
         [0056]      FIG. 1  is a schematic block diagram of an endoscopic surgical device according to the invention. As illustrated in  FIG. 1 , an endoscopic surgical device  10  includes an endoscope  100  that is one form of a first medical instrument having a first insertion part inserted into a body cavity and observes the inside of a patient&#39;s body cavity, a treatment tool  200  that is one form of a second medical instrument having a second insertion part inserted into the body cavity and examines or treats a diseased site within the patient&#39;s body cavity, an overtube  300  that is inserted into the body cavity through a body wall and guides an insertion part  102  of the endoscope  100 , which is a first insertion part, and an insertion part  202  of a treatment tool  200 , which is a second insertion part, to the inside of the body cavity, and a sheathing tube  500  fitted to the overtube  300 . 
         [0057]    The endoscope  100  is, for example, a hard endoscope, such as a laparoscope, and includes an insertion part  102  (hereinafter referred to as “endoscope insertion part  102 ”) that is inserted into a body cavity, and that has an outer peripheral part surrounded by an elongated hard tubular body, and a cable part  104  that is consecutively installed on a proximal end side of the endoscope insertion part  102  and that has an outer peripheral part surrounded by an elongated flexible tubular body. 
         [0058]    The cable part  104  indicates a flexible cable portion in which a wire rod, such as a cable or a light guide, which extends from a proximal end of the endoscope insertion part  102 , is housed by covering the wire rod with, for example, a flexible insulating member, such as polyvinyl chloride. 
         [0059]    A connector (not illustrated) is provided at an end of the cable part  104  on its extension destination, and each of a processor device  108  that is a control device and a light source device  110  is detachably connected to the cable part via the connector. Additionally, the processor device  108  is connected to a monitor  112  via a cable. 
         [0060]    As illustrated in  FIG. 2 , a distal end surface  114  of the endoscope insertion part  102  is provided with an observation window  116  and illumination windows  118  and  118 . 
         [0061]    A distal end of the endoscope insertion part  102  is provided with an observation part, and an observation window  116  is provided as a constituent element of the observation part. Additionally, as constituent elements of the observation part, and an objective lens of an observation optical system, and a solid image pickup element, such as a charge coupled device (CCD) image sensor or a complementary metal oxide semiconductor (CMOS) image sensor, which is disposed at an image pickup position of the objective lens, are disposed behind the observation window  116 . 
         [0062]    A signal cable (not illustrated) connected to this solid image pickup element is inserted through the endoscope insertion part  102  and the cable part  104  of  FIG. 1 , is provided to extend up to the connector (not illustrated), and is connected to the processor device  108 . An observation image picked up from the observation window  116  is formed on a light-receiving surface of the image pickup element, and is converted into electrical signals (image pickup signals), and the electrical signals are output to the processor device  108  via the signal cable and are converted into video signals. Then, the video signals are output to the monitor  112  connected to the processor device  108 , and the observation image (endoscopic image) is displayed on a screen of the monitor  112 . 
         [0063]    An emission end of the light guide (not illustrated) is disposed behind the illumination windows  118  and  118  of  FIG. 2  to constitute an illumination part. The light guide is inserted through the endoscope insertion part  102  and the cable part  104  of  FIG. 1  and has an incident end disposed within the connector (not illustrated). Hence, by coupling the connector to the light source device  110 , the illumination light radiated from the light source device  110  is transmitted to the illumination windows  118  and  118  via the light guide, and is radiated forward from the illumination windows  118  and  118 . In addition, in  FIG. 2 , the two illumination windows  118  and  118  are disposed on the distal end surface  114  of the endoscope insertion part  102 . However, the number of illumination windows  118  is not limited, and the number thereof may be one or may be three or more. Additionally, the endoscope  100  may not include the illumination part. 
         [0064]    As illustrated in  FIG. 1 , the treatment tool  200  consists of, for example, forceps, and includes an elongated insertion part  202  (hereinafter referred to as a “treatment tool insertion part  202 ”) that is inserted into a body cavity, an operating part  204  that is provided on the proximal end side of the treatment tool insertion part  202  and is gripped by an operator, and a treatment part  206  that is provided at a distal end of the treatment tool insertion part  202  and is operable by the operation of the operating part  204 . 
         [0065]    The treatment tool insertion part  202  is provided with a tubular sheath  208 , and an operating shaft (not illustrated) that is inserted into the sheath  208  so as to be movable in the direction of an axial center. Moreover, the operating part  204  is provided with a fixed handle  210 , and a movable handle  214  that is coupled to the fixed handle  210  in a rotationally movable manner via a rotational movement pin. A proximal end part of the operating shaft is coupled to the movable handle  214 . 
         [0066]    The treatment part  206  is provided with a pair of gripping members that is openable and closable. The gripping members are coupled to a distal end part of the operating shaft via a driving mechanism (not illustrated). With the rotational movement operation of the movable handle  214  of the operating part  204 , the gripping members of the treatment part  206  are opened and closed via the operating shaft and the driving mechanism. 
         [0067]    In addition, the treatment tool  200  is not limited to the forceps, and may be, for example, other treatment tools, such as a laser probe, a suture device, an electric scalpel, a needle holder, an ultrasonic device, and an aspirator. 
         [0068]    As illustrated in  FIG. 1 , the overtube  300  allows the endoscope insertion part  102  and the treatment tool insertion part  202 , which are inserted thereinto from the proximal end side, to be inserted therethrough and delivered from the distal end side. By inserting the overtube  300  into a body wall and having a proximal end side thereof disposed outside of the body and a distal end side thereof disposed within the body cavity, the endoscope insertion part  102  and the treatment tool insertion part  202  are guided into the body cavity with one overtube  300 . Additionally, the overtube  300  includes an interlocking function of moving the endoscope insertion part  102  and the treatment tool insertion part  202  forward and backward in an interlocking manner as will be described below in detail. For example, the endoscope insertion part  102  can also be moved forward and backward by the forward and backward movement operation of only the treatment tool insertion part  202 , and a suitable endoscopic image can be obtained without performing the forward and backward movement operation of the endoscope insertion part  102 . The details of the configuration and working of the overtube  300  will be described below. 
         [0069]    The sheathing tube  500  illustrated in  FIG. 1  is formed in a tubular shape, and as illustrated in  FIG. 3 , is externally fitted (sheathed) to and fixed to an outer peripheral surface of the overtube  300  (a long tubular overtube part  320  to be described below). Although detailed description is omitted, an outer peripheral part of the sheathing tube  500  is provided with a number of lateral grooves  520  running along in a circumferential direction, and four longitudinal grooves  504  running along an axial direction are provided, for example, in four places in the circumferential direction. 
         [0070]    Accordingly, in a state where the overtube  300  is inserted into a body wall together with the sheathing tube  500 , a number of the lateral grooves  520  of the sheathing tube  500  restrict the forward and backward movement of the sheathing tube  500  with respect to the body wall, and the longitudinal grooves in four places of the sheathing tube  500  restrict the rotation of the sheathing tube  500  in the circumferential direction (around a reference axis  300   a ) with respect to the body wall. Hence, unintended rotation or forward and backward movement of the overtube  300  fixed to the sheathing tube  500  with respect to the body wall is prevented. 
         [0071]    Namely, if the overtube  300  rotates in a direction around the axis with respect to the reference axis  300   a  that is a central axis (longitudinal axis) of the overtube  300  unintentionally with respect to the body wall or moves forward and backward in the direction (axial direction) of the reference axis  300   a  in a case where the operation of the treatment tool  200 , or the like is performed by inserting the endoscope insertion part  102  and the treatment tool insertion part  202  through the overtube  300  after the overtube  300  (long tubular overtube part  320 ) is inserted into the body wall, there is a problem that the position of a distal end of the endoscope insertion part  102  may fluctuate and an observation visual field may fluctuate unintentionally. The sheathing tube  500  prevents such unintended fluctuation of the observation visual field. 
         [0072]      FIG. 4  is an external perspective view illustrating the overtube  300 . 
         [0073]    As illustrated in this drawing, the overtube  300  has an elongated cylindrical shape as a whole, and has an endoscope insertion passage  306  through which the endoscope insertion part  102  of the endoscope  100  is inserted so as to be movable forward and backward along the reference axis  300   a  indicating a longitudinal axis thereof, and a treatment tool insertion passage  308  through which the treatment tool insertion part  202  of the treatment tool  200  is inserted so as to be movable forward and backward along the reference axis  300   a  indicating a longitudinal axis thereof. The endoscope insertion passage  306  is one form of a first insertion passage through which the first insertion part of the first medical instrument is inserted so as to be movable forward and backward, and the treatment tool insertion passage  308  is one form of a second insertion passage through which the second insertion part of the second medical instrument is inserted so as to so as to be movable forward and backward. 
         [0074]    Additionally, the endoscope insertion passage  306  and the treatment tool insertion passage  308  are disposed parallel to each other and are disposed parallel to the reference axis  300   a.  That is, in a case where a central axis of the endoscope insertion passage  306  is referred to as an endoscope insertion axis  306   a  and a central axis of the treatment tool insertion passage  308  is referred to as a treatment tool insertion axis  308   a,  the endoscope insertion axis  306   a  and the treatment tool insertion axis  308   a  are parallel to each other and are also parallel to the reference axis  300   a.  The endoscope insertion axes  306   a  and the treatment tool insertion axes  308   a  are equivalent to positions of the central axes of the endoscope insertion part  102  and the treatment tool insertion part  202  that are respectively inserted through the endoscope insertion passage  306  and the treatment tool insertion passage  308 . Additionally, in the present embodiment, the reference axis  300   a,  the endoscope insertion axis  306   a,  and the treatment tool insertion axis  308   a  are disposed on the same plane. However, a configuration in which the reference axis  300   a,  the endoscope insertion axis  306   a,  and the treatment tool insertion axis  308   a  are disposed on the same plane may not be adopted. 
         [0075]    In addition, regarding the position and orientation of a space where the overtube  300  has been disposed, terms called forward, backward, left, right, up, and down are used with the orientation from the proximal end surface  302  in a direction along the reference axis  300   a  to the distal end surface  304  defined as the forward and with the orientation from the reference axis  300   a  to the treatment tool insertion axis  308   a  defined as the right. 
         [0076]    The proximal end surface  302  of the overtube  300  is provided with a first proximal end opening  310  that is a proximal end opening that allows the endoscope insertion part  102  to be inserted into the endoscope insertion passage  306  therethrough, and a second proximal end opening  314  that is a proximal end opening that allows the treatment tool insertion part  202  to be inserted into the treatment tool insertion passage  308  therethrough. 
         [0077]    The distal end surface  304  of the overtube  300  is provided with a first distal end opening  312  that is a distal end opening that allows the endoscope insertion part  102  to be inserted into the endoscope insertion passage  306  and delivered to the outside therethrough, and a second distal end opening  316  that is a distal end opening that allows the treatment tool insertion part  202  to be inserted into the treatment tool insertion passage  308  and delivered to the outside therethrough. 
         [0078]    That is, the endoscope insertion passage  306  that is one form of the first insertion passage allows the first distal end opening  312  and the first proximal end opening  310  to communicate with each other, and the treatment tool insertion passage  308  that is one form of the second insertion passage is provided so as to allow the second distal end opening  316  and the second proximal end opening  314  to communicate with each other. 
         [0079]      FIG. 5  is a cross-sectional view illustrating the internal structure of the overtube  300 , and illustrates a cross section obtained by cutting the overtube  300  in a plane (horizontal plane) that includes the reference axis  300   a  and is orthogonal to an upward-downward direction. 
         [0080]    As illustrated in this drawing, the overtube  300  is constituted by a long tubular overtube part  320  that occupies portions other than a proximal end portion and a distal end portion, a proximal end cap  340  that is attached to a rear end (proximal end) of the overtube  300 , and a distal end cap  360  that is attached to a distal end part. 
         [0081]    Additionally, the long tubular overtube part  320  is constituted by a long tubular body  322  formed in an elongated cylindrical shape having the reference axis  300   a  as a central axis (longitudinal axis) using hard resin, metal, or the like, a columnar partition wall member  324  that is housed and disposed inside the long tubular body  322  and extends along the reference axis  300   a  and that has an endoscope guide groove  326  and a treatment tool guide groove  328  that respectively form portions of the endoscope insertion passage  306  and the treatment tool insertion passage  308 , and a slider  400  that is guided by the partition wall member  324  and supported to be movable forward and backward in the forward-backward direction. The details regarding the partition wall member  324  and the slider  400  will be described below. 
         [0082]    The proximal end cap  340  is formed in a columnar shape of which the diameter is made larger than the external diameter of the long tubular overtube part  320  (cylindrical body) using hard resins, metals, or the like, and a rear end surface thereof constitutes the proximal end surface  302  of the overtube  300 . The proximal end cap  340  is provided with a through-hole  342  and a through-hole  344  that form a portion of the endoscope insertion passage  306  and a portion of the treatment tool insertion passage  308 , respectively, and through-holes  342  and  344  respectively communicate with the endoscope guide groove  326  and the treatment tool guide groove  328  of the long tubular overtube part  320 . In the proximal end surface  302 , an opening of the through-hole  342  is equivalent to the above-described first proximal end opening  310 , and an opening of the through-hole  344  is equivalent to the above-described second proximal end opening  314 . 
         [0083]    Additionally, the through-holes  342  and  344  are provided with valve members  346  and  348 . The valve members  346  and  348 , for example, open in a case where the endoscope insertion part  102  and the treatment tool insertion part  202  are inserted therethrough and come into close contact with outer peripheral surfaces (side surfaces) of the endoscope insertion part  102  and the treatment tool insertion part  202  without a substantial gap. This secures the airtightness of spaces closer to the distal end side than the valve members  346  and  348 , and reduces the leakage or the like of a pneumoperitoneum gas injected into the body cavity to the outside of the body. 
         [0084]    The distal end cap  360  is formed of hard resins, metals, or the like, and a front end surface thereof constitutes the distal end surface  304  of the overtube  300 . The distal end cap  360  is provided with a through-hole  362  and a through-hole  364  that form a portion of the endoscope insertion passage  306  and a portion of the treatment tool insertion passage  308 , respectively, and through-holes  362  and  364  respectively communicate with the endoscope guide groove  326  and the treatment tool guide groove  328  of the long tubular overtube part  320 . In the distal end surface  304 , an opening of the through-hole  362  is equivalent to the above-described first distal end opening  312 , and an opening of the through-hole  364  is equivalent to the second distal end opening  316 . 
         [0085]    In addition, the long tubular overtube part  320 , the proximal end cap  340 , and the distal end cap  360  show one form of constituent members that constitutes the overtube body of the overtube  300 , and the overtube body is not limited to the above configuration. For example, the long tubular overtube part  320  and the proximal end cap  340  or the long tubular overtube part  320  and the distal end cap  360  may be integrally formed, or may be integrally formed in their entirety. 
         [0086]    The partition wall member  324  and the slider  400  in the above-described long tubular overtube part  320  constitute a coupling mechanism having a first coupling part coupled to the first insertion part of the first medical instrument inserted through the first insertion passage, and a second coupling part coupled to the second insertion part of the second medical instrument inserted through the second insertion passage. 
         [0087]      FIG. 6  is a partially enlarged view illustrating a portion, in which the slider  400  is disposed in  FIG. 5 , in an extracted manner, and  FIGS. 7 and 8  are perspective views illustrating the overtube  300  from left and right different directions on the proximal end side with the long tubular body  322  in the long tubular overtube part  320  omitted. As illustrated in these drawings, the slider  400  is supported by the columnar partition wall member  324  having the endoscope guide groove  326  and the treatment tool guide groove  328  inside the long tubular body  322 . 
         [0088]    The partition wall member  324  is a solid insulator, has a structure as illustrated in  FIG. 9 , and extends from the proximal end cap  340  to the distal end cap  360  inside the long tubular body  322 . 
         [0089]    The endoscope guide groove  326 , which forms a portion of the endoscope insertion passage  306  and extends parallel to the reference axis  300   a  from a proximal end of the partition wall member  324  to a distal end thereof, is formed on a left side of the partition wall member  324 . The treatment tool guide groove  328 , which forms a portion of the treatment tool insertion passage  308  and extends parallel to the reference axis  300   a  from the proximal end of the partition wall member  324  to the distal end thereof, is formed on a right side of the partition wall member  324 . 
         [0090]    That is, the partition wall member  324  has the endoscope guide groove  326  as one form of a first guide groove that constitutes a portion of the first insertion passage, and has the treatment tool guide groove  328  as one form of a second guide groove that constitutes a portion of the second insertion passage. Additionally, the partition wall member  324  forms a partition wall between the first insertion passage and the second insertion passage. 
         [0091]    By virtue of the partition wall member  324 , the endoscope insertion part  102  and the treatment tool insertion part  202  inserted into the overtube  300  reliably proceed through the regions of the endoscope insertion passage  306  and the treatment tool insertion passage  308  corresponding thereto without falling out of the insertion passages, respectively. As a result, the insertion task of the endoscope insertion part  102  with respect to the overtube  300  and the treatment tool insertion part  202  becomes easy. 
         [0092]    Additionally, the endoscope insertion part  102  inserted through the endoscope insertion passage  306  and the treatment tool insertion part  202  inserted through the treatment tool insertion passage  308  are prevented from coming into contact with each other inside then overtube  300 , and are electrically insulated from each other. For that reason, even in a case where the treatment tool  200  uses electricity, generation of electrical leakage (high-frequency electricity or the like) from the treatment tool  200  to the endoscope  100 , electrical noise, or the like can be prevented, and damage or the like to the endoscope  100  can be prevented in advance. 
         [0093]    In addition, the partition wall member  324  may act as at least a member that forms a partition wall between the endoscope insertion passage  306  (first insertion passage) and the treatment tool insertion passage  308  (second insertion passage), may not be necessarily formed on the basis of a columnar shape, and may not occupy substantially all regions other than the endoscope insertion passage  306  and treatment tool insertion passage  308  as in the present embodiment. 
         [0094]    As illustrated in  FIGS. 6, 7, and 8 , the slider  400  is a ring-shaped driving member that is externally fitted to an outer peripheral part of the partition wall member  324  and is movable forward and backward along the reference axis  300   a  with respect to the partition wall member  324 , and has a coupling ring  402  that integrally interlocks components of the slider  400 , an endoscope fixing tool  430  disposed as a first fixing tool inside the endoscope guide groove  326  of the partition wall member  324  as illustrated in  FIG. 6 , and a treatment tool fixing tool  450  disposed as a second fixing tool inside the treatment tool guide groove  328  of the partition wall member  324 . 
         [0095]    Only the coupling ring  402  is illustrated in  FIG. 10 . The coupling ring  402  has a tubular ring part  404  that surrounds an outer periphery of the partition wall member  324  in the circumferential direction and that comes into contact with contacts or approaches an outer peripheral surface of the partition wall member  324  in portions other than endoscope guide groove  326  and treatment tool guide groove  328 , and an arm part  406  consisting of a portion that faces the treatment tool guide groove  328  of the ring part  404  and a portion that extends in the forward-backward direction from the ring part  404  along a position that faces the treatment tool guide groove  328 . 
         [0096]    The arm part  406  acts as a second engaging part that is engaged with the treatment tool fixing tool  450  (refer to  FIG. 6 ) that is the second fixing tool, and a proximal end and a distal end of the arm part are respectively provided with a rear restriction end  408  and a front restriction end  410  that are a second restricting part which restricts the forward and backward movement of the treatment tool fixing tool  450  and that are inserted into and disposed in the inside of the treatment tool guide groove  328 . Also, the rear restriction end  408  and the front restriction end  410  are respectively provided with openings  408 A and  410 A through which the treatment tool insertion part  202  is inserted. 
         [0097]    Additionally, a first engaging part  404 A, which is engaged with the endoscope fixing tool  430  that is the first fixing tool and which extends in a leftward-rightward direction along a plane orthogonal to the forward-backward direction, is formed in a portion that is disposed to face the endoscope guide groove  326  in the ring part  404 . 
         [0098]    The rotation of the coupling ring  402  in the direction around the axis (a direction around the reference axis  300   a ) with respect to the partition wall member  324  is restricted by the rear restriction end  408  and the front restriction end  410  that are inserted into and disposed inside the first engaging part  404 A and the treatment tool guide groove  328 . 
         [0099]    Also, the coupling ring  402  is supported so as to be movable forward and backward in the forward-backward direction by the partition wall member  324  within the long tubular overtube part  320 , and is supported in a state where the movement of the slider in the upward-downward direction and in the leftward-rightward direction and the rotation of the slider in all directions (direction around three axes including a forward-backward axis, a leftward-rightward axis, and an upward-downward direction) are restricted (a state where the rotation of the slider around at least the reference axis  300   a  is impossible). Additionally, the coupling ring  402  moves forward and backward within a movable range having a position where the coupling ring  402  (rear restriction end  408 ) abuts against the proximal end cap  340  as a rear end, and having a position where the coupling ring  402  (front restriction end  410 ) abuts against the distal end cap  360  as a front end. 
         [0100]      FIG. 11  is a cross-sectional view when viewed from arrow A-A in  FIG. 6 , and  FIG. 12  is a perspective view illustrating the overtube  300  cut by in a plane perpendicular to the reference axis  300   a  at a position that intersects the arm part  406  closer to the proximal end side than the ring part  404  of the coupling ring  402  in the state of  FIG. 7 .  FIG. 13  is a perspective view illustrating the overtube of  FIG. 12  with the coupling ring  402  omitted, and  FIG. 14  is a perspective view illustrating the overtube  300  of  FIG. 13  from a right side. 
         [0101]    As illustrated in  FIGS. 6 and 11 , the slider  400  has a left endoscope coupling part  420  that is coupled to (engaged with) the endoscope insertion part  102  inside the coupling ring  402  and a right treatment tool coupling part  422  that is coupled to (engaged with) the treatment tool insertion part  202 . 
         [0102]    That is, the slider  400  has an endoscope coupling part  420  as the first coupling part coupled to the first insertion part of the first medical instrument inserted through the first insertion passage, and a treatment tool coupling part  422  as the second coupling part coupled to the second insertion part of the second medical instrument inserted through the second insertion passage. 
         [0103]    Specifically, as illustrated in  FIGS. 6, 11, and 13 , the endoscope coupling part  420  provided on a left side of the slider  400  includes the endoscope fixing tool  430  that is disposed inside the endoscope guide groove  326  and that is one form of the first fixing tool that is movable forward and backward in the forward-backward direction along the endoscope insertion passage  306 . 
         [0104]    The endoscope fixing tool  430  is constituted by a tubular frame  432  that approaches or comes into contact with an inner wall surface of the endoscope guide groove  326 , and a tubular pressure-contact member  434  that is fixed inside the frame  432  and formed of an elastic material, such as elastic rubber. 
         [0105]    An outer peripheral part of the frame  432  is provided with a protrusion  436  that protrudes in the radial direction from a position in the circumferential direction at a position that faces an opening of the endoscope guide groove  326 . As illustrated in  FIGS. 6, 10, and 12 , the protrusion  436  is inserted through an engagement hole  412  that is one form of a first restricting part formed in the first engaging part  404 A in the ring part  404  of the coupling ring  402 , and is locked to the engagement hole  412  in the forward-backward direction. 
         [0106]    According to this, due to the engagement between the protrusion  436  of the endoscope fixing tool  430  and the engagement hole  412  of the coupling ring  402 , the endoscope fixing tool  430  and the first engaging part  404 A are engaged with each other and the relative forward and backward movement of the endoscope fixing tool  430  in the forward-backward direction with respect to the coupling ring  402  is restricted. Hence, the coupling ring  402  and the endoscope fixing tool  430  integrally move forward and backward in the forward-backward direction. 
         [0107]    Additionally, when the endoscope insertion part  102  has been inserted through the endoscope insertion passage  306 , the endoscope insertion part  102  is inserted through the inside of the pressure-contact member  434 , and the endoscope fixing tool  430  is fixed to the endoscope insertion part  102  by the pressure-contact member  434  being brought into pressure contact with (engaged with) the outer peripheral surface of the endoscope insertion part  102 . Then, the central axis of the endoscope insertion part  102  is disposed substantially coaxially with the endoscope insertion axis  306   a.    
         [0108]    Accordingly, the endoscope insertion part  102  and the slider  400  (coupling ring  402 ) are coupled to (engaged with) each other in an interlocking manner via the endoscope fixing tool  430 , and the slider  400  (coupling ring  402 ) also integrally moves forward and backward in an interlocking manner with the forward and backward movement of the endoscope insertion part  102  in the forward-backward direction (axial direction). 
         [0109]    In addition, since the coupling herein is based on the elastic force of the pressure-contact member  434 , the engagement position (the position of the endoscope insertion part  102  where the slider  400  is engaged) of the endoscope insertion part  102  coupled to the slider  400  (coupling ring  402 ) can be arbitrarily adjusted. 
         [0110]    Additionally, the frame  432  of the endoscope fixing tool  430  has a shape such that the movement (rotation) thereof is impossible in the direction around the axis inside the endoscope guide groove  326 , and the endoscope fixing tool  430  is allowed only to move forward and backward in the forward-backward direction within the endoscope guide groove  326 . 
         [0111]    Specifically, as illustrated in  FIGS. 6, 11, and 14 , the treatment tool coupling part  422  provided on a right side of the slider  400  includes the treatment tool fixing tool  450  that is disposed in a range between the rear restriction end  408  and the front restriction end  410  (refer to  FIG. 10  or the like) of the arm part  406  of the coupling ring  402  inside the treatment tool guide groove  328 , and that is the second fixing tool that is movable forward and backward along the treatment tool guide groove  328 . 
         [0112]    The treatment tool fixing tool  450  is constituted by a tubular frame  452  that approaches or comes into contact with an inner wall surface of the treatment tool guide groove  328 , and a tubular pressure-contact member  454  that is fixed inside the frame  452  and formed of an elastic material, such as elastic rubber. In addition, an inner peripheral surface of the pressure-contact member  454  is formed in a shape such that regularities are repeated in the circumferential direction so as to be appropriately engageable with treatment tool insertion parts  202  having a plurality of types of greatly different diameters. 
         [0113]    According to this, when the treatment tool insertion part  202  has been inserted through the treatment tool insertion passage  308 , the treatment tool insertion part  202  is inserted through the inside of the pressure-contact member  454 , and the treatment tool fixing tool  450  is fixed to the treatment tool insertion part  202  by the pressure-contact member  454  being brought into pressure contact with (engaged with) the outer peripheral surface of the treatment tool insertion part  202 . Then, the central axis of the treatment tool insertion part  202  is disposed substantially coaxially with the treatment tool insertion axis  308   a.    
         [0114]    Accordingly, the treatment tool fixing tool  450  also integrally moves forward and backward in an interlocking manner with the forward and backward movement of the treatment tool insertion part  202  in the forward-backward direction (axial direction). Additionally, the treatment tool fixing tool  450  also rotates inside the treatment tool guide groove  328  in an interlocking manner with the rotation of the treatment tool insertion part  202  around the axis thereof. 
         [0115]    In addition, since the coupling between the treatment tool insertion part  202  and the treatment tool fixing tool  450  herein is based on the elastic force of the pressure-contact member  454 , the engagement position (the position of the treatment tool insertion part  202  where the treatment tool fixing tool  450  is engaged) of the treatment tool insertion part  202  coupled to the treatment tool fixing tool  450  can be arbitrarily adjusted. 
         [0116]    Additionally, the rear restriction end  408  in the arm part  406  of the coupling ring  402  is disposed on a rear side of the treatment tool fixing tool  450 , and the front restriction end  410  in the arm part  406  is disposed on a front side of the treatment tool fixing tool  450 . 
         [0117]    Hence, the arm part  406  allows the forward and backward movement of the treatment tool fixing tool  450  in the forward-backward direction with respect to the coupling ring  402  in a range from a position where the treatment tool fixing tool  450  abuts against the rear restriction end  408  to a position where the treatment tool fixing tool  450  abuts against the front restriction end  410 , and restricts the treatment tool fixing tool  450  in that range. 
         [0118]    In addition, in a case where a range where the treatment tool fixing tool  450  is movable forward and backward with respect to the coupling ring  402  is defined as a second range and a range where the of the endoscope fixing tool  430  is movable forward and backward with respect to the coupling ring  402  is defined as a first range, the first range becomes zero because the forward and backward movement of the endoscope fixing tool  430  in the forward-backward direction with respect to the first engaging part  404 A of the coupling ring  402  is restricted as described above. 
         [0119]    Accordingly, the coupling ring  402  has a non-sensing region where either the endoscope fixing tool  430  or the treatment tool fixing tool  450  is not moved forward and backward with the forward and backward movement of the other of the endoscope fixing tool  430  and the treatment tool fixing tool  450 . 
         [0120]    Meanwhile, in a case where the treatment tool fixing tool  450  moves forward and backward in the forward-backward direction or in a case where the coupling ring  402  moves forward and backward in the forward-backward direction together with the endoscope fixing tool  430 , the treatment tool fixing tool  450  abuts against the rear restriction end  408  or the front restriction end  410 . In this state, the coupling ring  402  has a sensing region where either the endoscope fixing tool  430  or the treatment tool fixing tool  450  is moved forward and backward movement with respect to the forward and backward movement (the forward and backward movement in a direction in which the treatment tool fixing tool  450  and the rear restriction end  408  or the front restriction end  410  are not spaced apart from each other) of other of the endoscope fixing tool  430  and the treatment tool fixing tool  450 . 
         [0121]    Due to the configuration of the above slider  400 , the slider  400  has the non-sensing region where either the endoscope insertion part  102  inserted through the endoscope insertion passage  306  of the overtube  300  and coupled to the endoscope fixing tool  430  or the treatment tool insertion part  202  inserted through the treatment tool insertion passage  308  and coupled to the treatment tool fixing tool  450  does not move forward and backward without interlocking with the forward and backward movement of the other in the forward-backward direction (axial direction) and the sensing region where either the endoscope insertion part  102  or the treatment tool insertion part  202  moves forward and backward in an interlocking manner with the forward and backward movement of the other. That is, the endoscope insertion part  102  is adapted to interlock with the forward and backward movement of the treatment tool insertion part  202  in the axial direction with play by the slider  400 . 
         [0122]    In addition, although the first range where the endoscope fixing tool  430  is movable forward and backward with respect to the coupling ring  402  is zero in the present embodiment, the forward and backward movement of the endoscope fixing tool  430  together with the treatment tool fixing tool  450  with respect to the coupling ring  402  or instead of the treatment tool fixing tool  450  may be allowed, and the first range may have a magnitude other than zero. Namely, a configuration in which the forward and backward movement of at least one of the endoscope fixing tool  430  and the treatment tool fixing tool  450  with respect to the coupling ring  402  is allowed may be adopted. 
         [0123]    In a case where the forward and backward movement of the endoscope fixing tool  430  with respect to the coupling ring  402  is allowed, for example, it is possible to adopt a form in which the range of the engagement hole  412  (refer to  FIGS. 6 and 10 , or the like) formed in the first engaging part  404 A of the coupling ring  402  and engaged with the protrusion  436  of the endoscope fixing tool  430  is increased in the forward-backward direction. Accordingly, the endoscope fixing tool  430  can be made movable forward and backward with respect to the coupling ring  402  with the length range of the engagement hole  412  in the forward-backward direction as the first range. Otherwise, by virtue of the same configuration as the rear restriction end  408  and the front restriction end  410  of the arm part  406  with respect to the treatment tool fixing tool  450 , the endoscope fixing tool  430  can be made movable forward and backward with respect to the coupling ring  402 . 
         [0124]    Additionally, in the present embodiment, the treatment tool fixing tool  450  may be made rotatable around an axis (treatment tool insertion axis  308   a ) within the treatment tool insertion passage  308 , and the treatment tool insertion part  202  may be made easily rotatable around the axis, the rotation of the treatment tool fixing tool  450  around the axis may be restricted. In this case, the above configuration in the case where the forward and backward movement of the endoscope fixing tool  430  with respect to the coupling ring  402  is allowed can also be adopted for the treatment tool fixing tool  450 . In addition, the endoscope fixing tool  430  may be rotatable around an axis (endoscope insertion axis  306   a ) within the endoscope insertion passage  306 . In that case, the configuration of the second engaging part (arm part  406 ) of the coupling ring  402  with respect to the treatment tool fixing tool  450  can be adopted for the endoscope fixing tool  430 . 
         [0125]    The working of the overtube  300  configured as described above will be described together with the operation in a case where the treatment of a diseased site within a patient&#39;s body cavity is performed using the endoscopic surgical device  10 . 
         [0126]    First, as illustrated in portion (A) of  FIG. 15 , after the overtube  300  is inserted into a patient&#39;s body wall and a pneumoperitoneum gas is injected into a body cavity, the endoscope  100  (endoscope insertion part  102 ) and the treatment tool  200  (treatment tool insertion part  202 ) are respectively inserted into the endoscope insertion passage  306  and the treatment tool insertion passage  308  of the overtube  300 , and the endoscope insertion part  102  and the treatment tool insertion part  202  are mounted on the overtube  300 . 
         [0127]    In this case, the endoscope insertion part  102  is reliably guided to a position, where the endoscope fixing tool  430  of the slider  400  is inserted, by the endoscope guide groove  326  of the partition wall member  324 , and is coupled to the endoscope fixing tool  430 . 
         [0128]    Similarly, the treatment tool insertion part  202  is guided reliably to a position, where the treatment tool fixing tool  450  of the slider  400  is inserted, by the treatment tool guide groove  328  of the partition wall member  324 , and is coupled to the treatment tool fixing tool  450 . 
         [0129]    In addition, although the sheathing tube  500  is not illustrated in  FIG. 15 , and  FIG. 16  illustrated therebelow, the sheathing tube  500  is fitted to the overtube  300  as illustrated in  FIG. 3 . However, it is also possible to use the overtube  300  without fitting the sheathing tube  500  thereto. 
         [0130]    It is assumed that the state of portion (A) of  FIG. 15  is a state illustrated in  FIG. 17 .  FIG. 17  is a cross-sectional view illustrating the state of the slider  400  coupled to the endoscope insertion part  102  and the treatment tool insertion part  202 , and illustrating a state where the treatment tool fixing tool  450  reaches neither a front end nor a rear end of a movable range thereof with respect to the coupling ring  402  (arm part  406 ). That is, a state where the treatment tool fixing tool  450  reaches neither the rear restriction end  408  nor the front restriction end  410  is illustrated. 
         [0131]    In this case, if the operator minutely moves the treatment tool insertion part  202  forward with his/her hand that is gripping the operating part  204  of the treatment tool  200 , only the treatment tool fixing tool  450  moves forward within the movable range thereof with respect to the coupling ring  402 , and the coupling ring  402  does not move with respect to the overtube  300  (long tubular overtube part  320 ). 
         [0132]    For that reason, with respect to the forward movement of the treatment tool insertion part  202  until the treatment tool fixing tool  450  reaches the front end (front restriction end  410 ) of the movable range thereof with respect to the coupling ring  402 , as illustrated in portion (B)  FIG. 15 , only the treatment tool insertion part  202  moves forward in a state where the endoscope insertion part  102  is stationary. That is, the slider  400  has the non-sensing region where the endoscope insertion part  102  does not interlock with the forward and backward movement of the treatment tool insertion part  202 , and the forward movement operation of the treatment tool  200  at this time becomes a forward and backward movement operation of the slider  400  in the non-sensing region. 
         [0133]    Similarly, in the state illustrated in  FIG. 17 , if the operator minutely moves the treatment tool insertion part  202  backward with his/her hand that is gripping the operating part  204  of the treatment tool  200 , only the treatment tool fixing tool  450  moves backward within the movable range thereof with respect to the coupling ring  402 , and the coupling ring  402  does not move with respect to the overtube  300  (long tubular overtube part  320 ). 
         [0134]    For that reason, with respect to the backward movement of the treatment tool insertion part  202  until the treatment tool fixing tool  450  reaches the rear end (rear restriction end  408 ) of the movable range thereof with respect to the coupling ring  402 , as illustrated in portion (C) of  FIG. 15(C) , only the treatment tool insertion part  202  moves backward in a state where the endoscope insertion part  102  is stationary. That is, the backward movement operation of the treatment tool  200  at this time becomes a backward movement operation of the slider  400  in the non-sensing region. 
         [0135]    Hence, since the endoscope  100  does not move forward and backward with respect to the minute forward and backward movement operation of the treatment tool  200 , that is, the forward and backward movement operation thereof in the non-sensing region, the range of an observation site, such as a distal end site of the treatment tool  200  or a body cavity inner site, to be displayed on the monitor  112  as an endoscopic image does not vary, and the size of an image of the observation site can be prevented from fluctuating according to minute displacement of the treatment tool  200 . Accordingly, a sense of perspective can be suitably maintained, and a stable endoscopic image can be provided. 
         [0136]    Meanwhile, if the operator greatly moves the treatment tool insertion part  202  forward with his/her hand that is gripping the operating part  204  of the treatment tool  200  in the state illustrated in  FIG. 17 , a state where the treatment tool fixing tool  450  reaches the front end (front restriction end  410 ) of the movable range thereof with respect to the coupling ring  402  as illustrated in  FIG. 18  is brought out after the forward movement of the treatment tool fixing tool  450  of the slider  400  in the non-sensing region until it abuts against the front end (front restriction end  410 ) of the movable range. Then, in a case where the treatment tool insertion part  202  further moves forward, the treatment tool fixing tool  450  and the coupling ring  402  move forward with respect to the long tubular overtube part  320  together with the treatment tool insertion part  202 . Then, the endoscope fixing tool  430  moves forward together with the coupling ring  402 , and the endoscope insertion part  102  moves forward together with the endoscope fixing tool  430 . Accordingly, the endoscope insertion part  102  moves forward in an interlocking manner with the treatment tool insertion part  202 . 
         [0137]    For that reason, with respect to the forward movement of the treatment tool insertion part  202  after the treatment tool fixing tool  450  reaches the front end (front restriction end  410 ) of the movable range thereof with respect to the coupling ring  402 , the endoscope insertion part  102  moves forward in an interlocking manner with the treatment tool insertion part  202  as illustrated in portion (B) of  FIG. 16 , compared to the state of portion (A) of  FIG. 16  illustrating the same state as portion (A) of  FIG. 15 . That is, the slider  400  has the sensing region where the endoscope insertion part  102  interlocks with the forward and backward movement of the treatment tool insertion part  202 , and the forward movement operation of the treatment tool  200  at this time becomes a forward movement operation of the slider  400  in the sensing region. 
         [0138]    Similarly, if the operator greatly moves the treatment tool insertion part  202  backward with his/her hand that is gripping the operating part  204  of the treatment tool  200  in the state illustrated in  FIG. 17 , a state where the treatment tool fixing tool  450  reaches the rear end (rear restriction end  408 ) of the movable range thereof with respect to the coupling ring  402  as illustrated in  FIG. 19  is brought out after the backward movement of the treatment tool fixing tool  450  of the slider  400  in the non-sensing region until it abuts against the rear end (rear restriction end  408 ) of the movable range. Then, in a case where the treatment tool insertion part  202  further moves backward, the treatment tool fixing tool  450  and the coupling ring  402  moves backward with respect to the long tubular overtube part  320  together with the treatment tool insertion part  202 . Then, the endoscope fixing tool  430  moves backward together with the coupling ring  402 , and the endoscope insertion part  102  moves backward together with the endoscope fixing tool  430 . Accordingly, the endoscope insertion part  102  moves backward in an interlocking manner with the treatment tool insertion part  202 . 
         [0139]    For that reason, with respect to the backward movement of the treatment tool insertion part  202  after the treatment tool fixing tool  450  reaches the rear end (rear restriction end  408 ) of the movable range thereof with respect to the coupling ring  402 , as illustrated in portion (C) of  FIG. 16 , the endoscope insertion part  102  moves backward in an interlocking manner with the treatment tool insertion part  202 . That is, the backward movement operation of the treatment tool  200  at this time becomes a backward movement operation of the slider  400  in the sensing region. 
         [0140]    Hence, since the endoscope  100  moves forward and backward with respect to a large forward and backward movement operation of the treatment tool  200 , that is, the forward and backward movement operation thereof in the sensing region, the range of an observation site that appears in an endoscopic image to be displayed on the monitor  112  is continuously changed so as to follow the forward and backward movement of the treatment tool  200 . Since the size of images of observation sites other than the distal end site of the treatment tool  200  that appears in the endoscopic image according to the operation of the treatment tool  200 , and the size of the range of the observation site varies, the operator can simply obtain a desired image. 
         [0141]    As described above, in a case where the displacement of the treatment tool insertion part  202  in the axial direction is large (in a case where a large amplitude of forward and backward movement operation has been performed) when an operator has moved the treatment tool insertion part  202  forward and backward in the axial direction, the endoscope insertion part  102  also moves forward, backward, up, down, right, and left in an interlocking manner. Thus, the visual field, orientation, and the like of the endoscope  100  can be changed as intended by an operator. Additionally, the visual field is always given to pick up an image of the distal end site of the treatment tool  200  and consequently, an image that is optimal for treatment is automatically provided. In a case where it is desired to check sites other than a site to be treated, the checking can be performed by moving the treatment tool insertion part  202 , and an operator can perform operations as desired. Hence, an assistant (endoscopic technician) who operates the endoscope  100  apart from the operator can be made unnecessary, and a troublesome condition in which the operator should instruct an assistant about the visual field, orientation, and the like of the endoscope  100  serially can be eliminated. 
         [0142]    Additionally, in a case where the displacement of the treatment tool insertion part  202  in the axial direction is small (in a case where a small amplitude of forward and backward movement has been performed), the endoscope insertion part  102  does not interlock. Therefore, an endoscopic image can be prevented from fluctuating unnecessarily, a sense of perspective can be suitably maintained, and a stable endoscopic image can be provided. 
         [0143]    As described above, in the above embodiment, the slider  400  (coupling ring  402 ) had the non-sensing region where either the endoscope insertion part  102  (endoscope fixing tool  430 ) or the treatment tool insertion part  202  (treatment tool fixing tool  450 ) does not move forward and backward with respect to the forward and backward movement of the other. However, the invention can also be applied to a case where the slider  400  (coupling ring  402 ) has no such a non-sensing region and has only the sensing region where either the endoscope insertion part  102  (endoscope fixing tool  430 ) or the treatment tool insertion part  202  (treatment tool fixing tool  450 ) moves forward and backward with respect to the forward and backward movement of the other. 
         [0144]    Additionally, in the above embodiment, the endoscope insertion passage  306  that is one form of the first insertion passage of the overtube  300  may be used as the second insertion passage, and the treatment tool insertion passage  308  that is one form of the second insertion passage may be used as the first insertion passage. 
         [0145]    Additionally, in the overtube  300  of the above embodiment, the insertion passage through which the endoscope  100  (endoscope insertion part  102 ) is inserted is used as the first insertion passage, and the insertion passage through which the treatment tool  200  (treatment tool insertion part  202 ) is inserted is used as the second insertion passage. The invention is not limited to this, and can be applied to an overtube including the first insertion passage through which the first insertion part of the first medical instrument of the first medical instrument and the second medical instrument that are arbitrary types of two medical instruments is inserted, and the second insertion passage through which the second insertion part of the second medical instrument is inserted. 
         [0146]    Additionally, in the overtube  300  of the above embodiment, the endoscope insertion passage  306  that is the first insertion passage, and the treatment tool insertion passage  308  that is the second insertion passage are disposed parallel to each other. However, the invention is not limited to this, and can also be applied to overtubes in which the first insertion passage and the second insertion passage obliquely intersect each other. 
         [0147]    That is, in the above embodiment, if the endoscope insertion axis  306   a  that is the central axis of the endoscope insertion passage  306  and the treatment tool insertion axis  308   a  that is the central axis of the treatment tool insertion passage  308  are parallel to the reference axis  300   a,  and the endoscope insertion axis  306   a  and the treatment tool insertion axis  308   a  are parallel to each other, these axes may not be necessarily parallel to each other. 
         [0148]    For example, the invention can also be applied to a form in which the treatment tool insertion passage  308  that is the second insertion passage is disposed parallel to the reference axis  300   a  as in the above embodiment, and the endoscope insertion passage  306  that is the first insertion passage is disposed to obliquely intersect the reference axis  300   a.  The overtube of this form will be specifically described as a modification example of the overtube  300  of the above embodiment. In the following embodiment shown as the modification example, constituent elements having functions that are the same as or similar to those of the constituent elements of the above embodiment will be designated by the same reference signs. 
         [0149]      FIG. 20  is an external perspective view of the overtube  300  that is the modification example. 
         [0150]    In this drawing, the treatment tool insertion axis  308   a  of the treatment tool insertion passage  308  is disposed parallel to the reference axis  300   a  of the overtube  300 , and the endoscope insertion axis  306   a  of the endoscope insertion passage  306  obliquely intersects the reference axis  300   a.    
         [0151]    That is, in a case where a plane along the upward-downward direction including the reference axis  300   a  is referred to as a vertical reference plane and a plane along the leftward-rightward direction including the reference axis  300   a  is referred to as a horizontal reference plane, the treatment tool insertion axis  308   a  is parallel to both the horizontal reference plane and the vertical reference plane. 
         [0152]    Meanwhile, the endoscope insertion axis  306   a  is parallel to the vertical reference plane and is not parallel to the horizontal reference plane. That is, the endoscope insertion axis  306   a  is obliquely inclined with respect to the horizontal reference plane. Also, the endoscope insertion axis  306   a  is inclined from a rear lower side toward a front upper side, and for example, intersects the horizontal reference plane at a substantially intermediate position of the overtube  300  in the forward-backward direction. 
         [0153]    In a case where the overtube  300  illustrated in this  FIG. 20  is configured, the endoscope guide groove  326  in the long tubular overtube part  320 , the through-hole  342  in the proximal end cap  340 , and the through-hole  362  in the distal end cap  360  are obliquely formed with respect to the horizontal reference plane along the endoscope insertion axis  306   a.    
         [0154]      FIGS. 21 and 22  are perspective views illustrating the partition wall member  324  and the slider  400  in the long tubular overtube part  320  in a case where the overtube  300  of  FIG. 20  is configured. As illustrated in  FIG. 22 , the treatment tool guide groove  328  of the partition wall member  324  is formed along the treatment tool insertion axis  308   a  parallel to the reference axis  300   a  as in the above embodiment. 
         [0155]    Meanwhile, as illustrated in  FIG. 21 , the endoscope guide groove  326  of the partition wall member  324  is not parallel to the reference axis  300   a,  and is formed along the endoscope insertion axis  306   a  that is oblique with respect to the horizontal reference plane. 
         [0156]    Additionally, since the endoscope fixing tool  430  disposed inside the endoscope guide groove  326  moves also in the upward-downward direction with respect to the partition wall member  324  and the coupling ring  402  together with the forward and backward movement in the forward-backward direction, the protrusion  436  formed on the outer peripheral part of the endoscope fixing tool  430  also moves in the upward-downward direction with respect to the coupling ring  402  according to the position of the endoscope fixing tool  430  in the forward-backward direction. 
         [0157]    Thus, the engagement hole  412  formed in the flat first engaging part  404 A of the coupling ring  402  is formed as an elongated hole that extends in the circumferential direction (upward-downward direction) beyond the range of the first engaging part  404 A as illustrated in the enlarged view of  FIG. 23  so as to be engaged with of the protrusion  436  at an arbitrary position of a movement range of the protrusion  436  in the upward-downward direction. 
         [0158]    Additionally, since the first engaging part  404 A of the coupling ring  402  is the plane orthogonal to the leftward-rightward direction, the distance between the outer peripheral surface of the endoscope fixing tool  430  (not illustrated) and the first engaging part  404 A is uniformly maintained irrespective of the movement of the endoscope fixing tool  430  in the upward-downward direction with respect to the coupling ring  402 . For that reason, the amount of protrusion of the protrusion  436  can be reduced, and the diameter of the long tubular overtube part  320  can be reduced. 
         [0159]    Meanwhile, in a case where the endoscope guide groove  326  is obliquely formed, the opening of the endoscope guide groove  326  deviates from a position that faces the first engaging part  404 A. Therefore, the range of the partition wall member  324  through which the first engaging part  404 A passes due to the movement of the coupling ring  402  in the forward-backward direction is cut out along a flat surface so as not to interfere with the first engaging part  404 A. 
         [0160]    According to such an overtube  300 , the distal end of the endoscope insertion part  102  and the distal end of the treatment tool insertion part  202  through which the overtube  300  is inserted can be spaced apart from each other even in a case where the spacing between the endoscope insertion passage  306  and the treatment tool insertion passage  308  in the overtube  300  is narrowed for reduction in diameter. Therefore, there is an advantage that the state of the distal end (treatment part  206 ) of the treatment tool  200  with an endoscope  100  is easily observed. 
       EXPLANATION OF REFERENCES 
       [0161]      10 : endoscopic surgical device 
         [0162]      100 : endoscope 
         [0163]      102 : endoscope insertion part 
         [0164]      200 : treatment tool 
         [0165]      202 : treatment tool insertion part 
         [0166]      300 : overtube 
         [0167]      300   a:  reference axis 
         [0168]      302 : proximal end surface 
         [0169]      304 : distal end surface 
         [0170]      306 : endoscope insertion passage 
         [0171]      306   a:  endoscope insertion axis 
         [0172]      308 : treatment tool insertion passage 
         [0173]      308   a:  treatment tool insertion axis 
         [0174]      310 : first proximal end opening 
         [0175]      312 : first distal end opening 
         [0176]      314 : second proximal end opening 
         [0177]      316 : second distal end opening 
         [0178]      320 : long tubular overtube part 
         [0179]      322 : long tubular body 
         [0180]      324 : partition wall member 
         [0181]      326 : endoscope guide groove 
         [0182]      328 : treatment tool guide groove 
         [0183]      340 : proximal end cap 
         [0184]      360 : distal end cap 
         [0185]      400 : slider 
         [0186]      402 : coupling ring 
         [0187]      404 : ring part 
         [0188]      404 A: first engaging part 
         [0189]      406 : aim part 
         [0190]      408 : rear restriction end 
         [0191]      410 : front restriction end 
         [0192]      412 : engagement hole 
         [0193]      420 : endoscope coupling part 
         [0194]      422 : treatment tool coupling part 
         [0195]      430 : endoscope fixing tool 
         [0196]      432 ,  452 : frame 
         [0197]      434 ,  454 : pressure-contact member 
         [0198]      436 : protrusion 
         [0199]      450 : treatment tool fixing tool 
         [0200]      500 : sheathing tube