Abstract:
A microsurgical instrument has a pair of operative surgical surfaces that are moved relative to each other in shearing or grasping procedures performed by the instrument. The instrument has a handle containing an elongate center rod with a ring mounted for reciprocating movement on the rod. A tube is secured to the ring and a shaft extends through the tube and is secured to the rod. The handle also includes a plurality of resilient arms that extend along the length of the rod and engage against a sliding surface of the ring on the rod. The plurality of actuator arms are alternatively manually compressed radially inwardly by the surgeon&#39;s hand and released by the surgeon&#39;s hand to allow the arms to flex radially inwardly and outwardly. The inward and outward movement of the plurality of arms reciprocates the ring on the handle rod and causes the tube and shaft to move axially relative to each other.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention pertains to a microsurgical instrument having a pair of operative surgical surfaces that are moved relative to each other in shearing or grasping procedures performed by the instrument, where the surgical instrument has an actuator handle with actuators that are radially compressed by the fingers of an operator&#39;s hand in controlling the movement of the operative surgical surfaces. 
         [0003]    2. Description of the Related Art 
         [0004]    Microsurgical instruments are those types of surgical instruments employed in performing surgical operations on extremely small and extremely delicate parts of the human anatomy, for example the tissues inside the human eye. There are many different types of microsurgical instruments. The more complex in construction are microsurgical instruments that have at least one pair of operative surgical surfaces that move relative to each other when using the instrument. By operative surgical surfaces what is meant is, for example, the opposed shearing surfaces of a scissors that have shearing edges that move across each other in a shearing operation performed by the instrument, or the opposed grasping surfaces of a forceps that move toward and away from each other in a grasping operation performed by the instrument. In microsurgical instruments of this type, the scale of the instrument must be as small as possible so that the introduction of the instrument to the surgical site is minimally invasive. 
         [0005]    A typical microsurgical instrument is comprised of a manual handle that is similar in size and shape to a pen or pencil. This enables the instrument to be easily manipulated by the fingers on one hand of a surgeon. An example of this type of instrument is disclosed in U.S. Pat. No. 5,370,658, assigned to the assignee of the present invention and incorporated herein by reference. 
         [0006]    Microsurgical instrument tips of the type disclosed in the above-referenced patent often comprise a hollow, narrow tube projecting from the instrument handle. A narrow fiber or shaft is received in the tube and the shaft and tube are caused to reciprocate relative to each other in response to manual manipulation of some type of actuator on the instrument handle. The relative movement between the shaft and tube operates the surgical instrument formed at the distal ends of the shaft and tube. Where the surgical instrument is a forceps, the opposed jaws of the forceps are formed at the shaft distal end and moving the tube over the shaft or retracting the shaft into the tube causes the forceps jaws to move toward each other. The reverse movements of the tube and shaft cause the jaws to separate from each other. Where the surgical instrument is a scissors, one of the shear surfaces is formed at the distal end of the shaft and the other shear surface is formed at the distal end of the tube. Moving the tube distal end toward the shaft distal end causes the shear surfaces and their shearing edges to move toward and across each other. 
         [0007]    As stated earlier, for microsurgical applications, the surgical instruments discussed above must be manufactured in an extremely small scale. The small scale of the microsurgical instrument results in the operative microsurgical surfaces of the instrument moving relative to each other in response to the slightest movement of the instrument actuator by the fingers of the surgeon&#39;s hand. 
       SUMMARY OF THE INVENTION 
       [0008]    It is therefore desirable that the microsurgical instrument have a handle that fits comfortably in the surgeon&#39;s hand and is easily rotated or otherwise moved in the surgeon&#39;s hand by slight manipulations of the fingers. It is also desirable that the actuator of the microsurgical instrument be easily and comfortably operated by the fingers of the surgeon&#39;s hand in any position of the instrument handle in the hand. It is also desirable that any resistance to the movement of the actuator of the surgical instrument be minimized. 
         [0009]    The microsurgical instrument of the present invention is basically comprised of a surgical instrument head and a handle attached to the head. The surgical instrument head includes an elongate, narrow tube and a shaft or fiber that extends through the tube. The tube and shaft axially reciprocate relative to each other. The reciprocating movements of the tube and shaft produce movements of operative microsurgical surfaces of the instrument. 
         [0010]    The microsurgical instrument also includes a rod having a length with opposite proximal and distal ends. The surgical instrument head is positioned at the distal end of the rod. 
         [0011]    A ring is mounted on the rod for axially reciprocating movement between first and second positions of the ring along the rod length. The ring is movable toward the rod proximal end to the first position of the ring on the rod and the ring is movable toward the rod distal end to the second position of the ring on the rod. A conical surface is provided on the ring. The conical surface has a first hardness. In other embodiments of the instrument the ring surface could have a convex shape or a concave shape. 
         [0012]    The instrument handle is provided on the rod proximal end. The handle has a plurality of arms that are circumferentially spaced around the rod. There are a plurality of axially extending slots between adjacent arms of the plurality of arms. The plurality of arms extend axially from the rod proximal end along the rod to free distal end surfaces of the arms. The free distal end surfaces of the arms have convex surfaces that are spaced radially outwardly from and surround the conical surface on the ring. Manually pressing the actuator arms radially inwardly with the fingertips causes the free distal ends of at least some of the arms to engage with and slide over the conical surface on the ring. This in turn causes the ring to move axially on the rod from the first position of the ring on the rod toward the second position of the ring on the rod. Releasing the manual force on the actuator arms allows the resilience of the arms to move the arms radially outwardly. The arms could also be spring biased to move radially outwardly. As the arms move outwardly a spring on the rod moves the ring from the second position of the ring on the rod toward the first position of the ring on the rod. This movement of the ring could also cause the ring conical surface to push the arms radially outwardly. The reciprocation of the ring on the rod produces relative axial reciprocating movements between the tube and shaft of the surgical instrument that in turn move the operative microsurgical surfaces of the instrument. The convex surfaces on the arm distal ends and the conical surface of the ring minimize the areas of contact between the arms and the ring and thereby minimize sliding friction between the distal end surfaces of the arms and the ring surface. In other embodiments the arm distal ends could each have a point that contacts the conical surface of the ring or a roller bearing or some other equivalent means of reducing the friction between the arm and the ring conical surface. The circumferential positioning of the arms around the ring enables the arms to be manually moved in any rotated position of the instrument in the surgeon&#39;s hands. 
         [0013]    In addition, in an embodiment of the instrument, the surface on the ring is constructed of a material having a hardness that is greater than the hardness of the surfaces of the arms engaging the ring. The harder ring surface resists wear to the surface due to repeated radially sliding movements of the surfaces on the arms over the surface on the ring. Employing a stainless steel surface or other equivalent low friction surface on the ring further reduces friction between the surface on the ring and the surfaces on the actuator arms. 
         [0014]    Still further, in an embodiment, the exterior surface of each of the actuator arms is configured in a manner that avoids any potential pinching of the surgeon&#39;s fingers between adjacent arms as the arms are moved radially toward each other by the surgeon&#39;s fingers compressing the arms. 
         [0015]    Further features and advantages of the present invention, as well as the structure and operation of the present invention, are described in detail below with reference to the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]    The accompanying drawings, which are incorporated in and form a part of the specification, illustrate the present invention and together with the description, serve to explain the principles of the invention. 
           [0017]      FIG. 1  is a front perspective view of the microsurgical instrument of the invention. 
           [0018]      FIG. 2  is a rear perspective view of the microsurgical instrument of the invention. 
           [0019]      FIG. 3  is a cross-section side view of the microsurgical instrument of the invention. 
           [0020]      FIG. 4  is a cross-section side view of the microsurgical instrument rotated 90 degrees from the position of the instrument shown in  FIG. 3 . 
           [0021]      FIG. 5  is an exploded view of the component parts of the microsurgical instrument. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0022]    The microsurgical instrument of the present invention is operable to axially reciprocate a tube and shaft of a surgical instrument similar to the microsurgical instruments disclosed in U.S. Pat. No. 5,370,658 which is assigned to the assignee of this application and is incorporated herein by reference. In surgical instruments of this type a narrow, cylindrical shaft or fiber extends through a narrow tube and the shaft and tube are reciprocated relative to each other to produce relative movement between the operative microsurgical surfaces of the instrument. The shaft can move in reciprocating movements relative to a stationary tube, or the tube can move in reciprocating movements relative to a stationary shaft. As described in the above-referenced patent, those operative microsurgical surfaces can be the surfaces of a microsurgical instrument such as a scissors or forceps. 
         [0023]    The microsurgical instrument  10  of the present invention is shown in a front perspective view in  FIG. 1  and a rear perspective in  FIG. 2 . The component parts of the instrument  10  are shown in an exploded view in  FIG. 5 . In the preferred embodiment of the invention, all of the component parts of the instrument  10  to be described are constructed of a material that is capable of being sterilized, for example stainless steel and alloys of titanium or aluminum. However, it should be understood that the preferences set forth herein are not intended to be limiting and the instrument of the invention may be constructed from a variety of materials suitable for the purposes herein described. 
         [0024]    The base of the microsurgical instrument  10  is an elongate cylindrical rod  12 . The rod  12  has opposite proximal  14  and distal  16  ends and a center axis  18  that defines mutually perpendicular axial and radial directions relative to the microsurgical instrument  10 . External screw threading  22  is formed on the rod  12  adjacent the rod proximal end  14 . As shown in the drawing figures, the screw threading  22  extends from the rod proximal end  14  over the exterior surface of the rod  12  toward the rod distal end  16 , but ends well short of the rod distal end. An elongate slot  24  is formed radially halfway through the width of the rod. The slot  24  extends through the center of the rod  12  from the rod proximal end  14  toward the rod distal end  16 , but ends short of the rod distal end. A pin hole  26  extends through the width of the rod  12  and intersects the slot  24 . The pin hole  26  is oriented perpendicular to the slot  24  and is located at an intermediate position along the rod length. A portion of the rod exterior surface  28  adjacent the rod distal end  16  is necked down. This portion of the rod  28  has a smaller diameter and a smaller circumference than the remainder of the rod exterior surface. A small center bore  32  is formed in the rod at the rod distal end  16 . The center bore  32  has a center axis that is coaxial with the rod center axis  18 . The center bore  32  extends from the rod distal end  16  through the center of the rod and intersects the slot  24 . As the center bore  32  approaches the slot  24 , the interior diameter of the bore increases forming an enlarged portion  34  of the bore that intersects the slot  24 . 
         [0025]    An instrument head  36  is mounted on the rod distal end  16 . The instrument head  36  has a cylindrical center bore  38  that receives the rod necked down portion  28  at the rod distal end  16 . The instrument head center bore  38  is press fit on the rod necked down portion  28  in securing the head  36  to the rod  12 . Other means of securing the head  36  to the rod  12  could also be employed, for example employing adhesives to secure the head  36  to the rod  12  or making the head  36  an integral part of the rod  12 . The instrument head  36  has a bulbous, generally convex distal end surface  42  that faces toward the rod distal end  16 . A cylindrical wall  44  projects axially from the periphery of the head distal end surface  42  toward the rod proximal end  14 . The wall  44  forms a cylindrical cavity  46  in an opposite side of the instrument head  36  from the head distal end surface  42 . 
         [0026]    A straight, narrow elongate tube  52  extends through the rod center bore  32  and the instrument head center bore  38 . The tube  52  has a narrow, elongate length with opposite proximal  54  and distal  56  ends and a center axis that is coaxial with the rod center axis  18 . In the preferred embodiment of the invention, the tube  52  has a construction similar to that of a hypodermic needle. The tube  52  is received through the rod center bore  32  and the instrument head center bore  38  for axially reciprocating movements of the tube  52  relative to the rod  12  and the instrument head  36 . As described earlier, the tube distal end  56  forms a part of an operative microsurgical instrument that is similar to those of the earlier-referenced U.S. Pat. No. 5,370,658. 
         [0027]    A rigid, straight narrow shaft  62  extends through the center of the tube  52 . The shaft  62  has an elongate length with opposite proximal  64  and distal  66  ends and a center axis that is coaxial with the rod center axis  18 . The shaft distal end  66  projects a short distance from the tube distal end  56  and forms the second part of the operative microsurgical instrument similar to those of the earlier referenced U.S. patent. The elongate length of the shaft  62  extends well beyond the tube proximal end  54  and through the rod slot  24  to the shaft proximal end  64 . In the preferred embodiment of the invention, the shaft  62  is straight and rigid such as a length of rigid wire. However, in alternate embodiments of the microsurgical instrument  10 , the shaft  62  can have a different construction, for example the construction of an optic fiber employed as an illumination light source or a laser light source in the microsurgical instrument  10 . 
         [0028]    A cylindrical tubular pin  72  extends through the pin hole  26  of the rod  12 . The pin  72  has an internally threaded center bore with a center axis (not shown) that is perpendicular to the rod center axis  18 . A pair of screws  74  are screw threaded into the pin center bore in the opposite ends of the pin  72 . A shaft hole  76  extends through the pin  72  and is oriented perpendicular to the center bore of the pin. The shaft  62  extends through the shaft hole  76 . The pin screws  74  are tightened down in the pin center bore at the opposite ends of the pin  72  and engage the shaft  62  between the screws  74  thereby securing the shaft  62  to the pin  72 . In this manner, the pin  72  secures the shaft  62  relative to the rod  12 . 
         [0029]    With the tube  52  being capable of axially reciprocating movements relative to the rod  12  and the instrument head  36  as described above, the tube  52  is also capable of axially reciprocating movements over the shaft  62  secured to the rod. However, as described in the earlier referenced U.S. patent, the tube  52  could be secured to the rod  12  and the shaft  62  could be capable of axially reciprocating movements relative to the rod  12 , the instrument head  36  and the tube  52 . 
         [0030]    A coil spring  82  is received in the enlarged portion  34  of the rod center bore. The coil spring  82  surrounds the tube  52  and the shaft  62  extending through the tube. The spring  82  has a distal end  84  that engages against an interior surface of the rod  12  at the bottom of the enlarged portion of the rod center bore  34 . The opposite proximal end  86  of the spring  82  is positioned in a part of the enlarged portion  34  of the rod center bore  32  that intersects the rod slot  24 . 
         [0031]    A ring  92  is mounted on the rod  12  for axially reciprocating sliding movement of the ring  92  over the rod  12 . The ring  92  has a hollow interior bore  94  that extends through the ring  92 . The rod  12  extends through the ring bore  94 . The ring  92  is movable on the rod  12  toward the rod proximal end  14  to a first position of the ring  92  on the rod  12 , and toward the rod distal end  16  to a second position of the ring  92  on the rod  12 . The ring  92  has a cylindrical base  96  at the ring proximal end. The ring  92  also has a generally conical portion  98  on the distal end of the ring  92 . The generally conical portion  98  of the ring  92  has an exterior sliding surface  102 . In the preferred embodiment, the sliding surface  102  has a conical configuration. In other embodiments the surface  102  could have more of a convex configuration or more of a concave configuration. The sliding surface  102  on the ring  92  also has a first hardness. In the preferred embodiment, the sliding surface  102  on the ring  92  is an exterior surface of the ring itself. In alternate embodiments, the sliding surface  102  on the ring  92  could be a separate component part secured to the generally conical portion  98  of the ring. For example, the sliding surface  102  could be a stainless steel cap or a Teflon surface secured to or applied to the generally conical portion  98  of the ring  92 . In further embodiments, the entire ring  92  could be constructed of stainless steel or a material of similar hardness and having a similar coefficient of friction. A bar  104  extends radially inwardly from the ring conical portion  98  into the ring interior bore  94 . The bar  104  extends into the slot  24  on the rod  12  and thereby prevents the ring  92  from rotating on the rod  12  as the ring  92  reciprocates over the rod  12 . A tube hole  106  extends through the bar  104 . The tube hole has a center axis that is coaxial with the rod center axis  18 . 
         [0032]    The tube proximal end  54  is press fit into the bar tube hole  106  and is securely attached to the bar  104  and the ring  92 . When the ring  92  axially reciprocates on the rod  12 , the tube  52  axially reciprocates through the rod center bore  32  and the instrument head center bore  38 . 
         [0033]    A connection collar  112  is screw threaded onto the external screw threading  22  of the rod  12 . The connection collar  112  has an interior bore and internal screw threading  114  that mates or threads with the external screw threading  22  on the rod  12 . By turning the connection collar  112  on the rod screw threading  22 , the axial position of the collar  112  relative to the rod  12  can be adjusted. The collar  112  has a cylindrical exterior surface that is defined by an intermediate portion  116  of the surface between a proximal end portion  118  and a distal end portion  122  of the surface. The intermediate portion  116  of the connection collar exterior surface is necked down and has a circumferential dimension and a diameter dimension that are slightly smaller than the respective circumferential dimensions and diameter dimensions of the proximal end portion  118  and the distal end portion  122  of the connection collar exterior surface. 
         [0034]    A locking hub  132  is secured in the connection collar internal screw threading  114  adjacent the rod proximal end  14 . The hub  132  has an interior bore  134  that extends completely through the hub  132 . The interior bore  134  has a hexagon configuration defined by an interior surface  136  of the locking hub  132  that surrounds the bore  134 . The hub  132  is constructed of a semi-rigid material, for example a plastic material that is self-threading into the internal screw threading  114  of a connection collar  112 . The hexagon configuration of the hub interior surface  136  allows a tool such as an Allen wrench to be inserted into the locking hub bore  134  to assist in screw threading the hub  132  into the connection collar internal screw threading  114 . 
         [0035]    The handle of the microsurgical instrument  10  is comprised of a handle rearward portion  142  and a handle forward portion  144 . Although the handle of the described embodiment is provided in two parts, in alternate embodiments of the instrument  10 , the handle could be a single, monolithic part comprised of the rearward portion  142  and the forward portion  144 . Additionally, the handle rearward portion  142  could be removable from the handle forward portion  144  to enable use of the instrument  10  with only the handle forward portion  144  if desired. In a further embodiment the handle could be comprised of only the forward portion  144 . 
         [0036]    The handle rearward portion  142  has a generally cylindrical length with opposite proximal  146  and distal  148  ends. The exterior surface of the rearward portion has a smooth, curved configuration designed to fit comfortably behind the web of the surgeon&#39;s hand between the thumb and forefinger. The handle rearward portion  142  has a circumferential dimension and an exterior diameter dimension at the distal end  148  that gradually increases as the handle rearward portion  142  extends from the distal end  148  toward the proximal end  146 . At about the midpoint of the length of the handle rearward portion  142  the circumferential dimension and exterior diameter dimension begin to decrease as the handle rearward portion  142  extends toward the proximal end  146 . This provides the handle rearward portion  142  with the comfortably-shaped exterior surface shown in the drawing figures that rests comfortably on the surgeon&#39;s hand behind the web between the thumb and forefinger. 
         [0037]    The handle rearward portion  142  has an interior bore  152  that extends completely through the rearward portion  142 . The interior bore  152  extending from the handle proximal end  146  is defined by a first interior surface  154  having a reduced interior diameter. As the interior bore  152  continues to extend toward the handle distal end  148  from the first interior surface  154 , the bore becomes larger and is defined by a second cylindrical interior surface  156  having a much larger interior diameter dimension than the first interior surface  154 . This second interior surface  156  extends through the handle to the handle distal end  148 . 
         [0038]    The handle forward portion  144  also has a generally cylindrical length between a proximal end  162  and a distal end  164  of the handle forward portion  144 . A cylindrical interior bore  166  extends completely through the handle forward portion  144 . The exterior surface of the handle forward portion  144  has a cylindrical, necked down portion  168  adjacent the proximal end  162 . This portion  168  of the exterior surface is dimensioned to be securely press fit into the second interior surface  156  of the handle rearward portion  142  in attaching the handle forward portion  144  to the handle rearward portion  142 . As explained earlier, the press fit connection could enable the handle rearward portion  142  to be selectively removable from the handle forward portion  144 . Instead of the press-fit connection, other equivalent connections could be employed such as an adhesive connection or a screw-threaded connection. As the exterior surface of the handle forward portion  144  extends from the necked down portion  168  toward the distal end  164 , the exterior surface  170  increases in circumferential dimension and exterior diameter dimension to substantially the same as that of the handle rearward portion  142  at the rearward portion distal end  148 . This provides for a smooth transition between the exterior surface of the handle rearward portion  142  to the handle forward portion  144 . As the exterior surface  170  of the handle forward portion  144  continues to extend toward the distal end  164  of the handle forward portion, the circumferential dimension and exterior diameter dimension of the exterior surface  170  gradually increase and provide the handle forward portion  144  with the smooth and comfortable exterior surface  170  positioned for gripping by the surgeon&#39;s fingertips as shown in the drawing figures. A plurality of circumferential serrations  172  are formed in this area of the exterior surface  170  of the handle forward portion  144  to enhance the grip of the surgeon&#39;s fingers on the surface. Beyond the serrations  172  the distal end of the handle forward portion  144  is formed with a rounded, convex surface  174  that curves around the distal end  164  from the handle forward portion exterior surface  170  to the handle forward portion interior bore  166 . 
         [0039]    The interior bore  166  of the handle forward portion  144  is defined by a first cylindrical interior surface  182  that extends through the handle forward portion  144  from the forward portion proximal end  162 . At about the mid-point of the length of the handle forward portion  144 , the cylindrical interior surface surrounding the interior bore increases to a second cylindrical interior surface  184  having an interior diameter dimension that is larger than the first cylindrical interior surface  182 . The second cylindrical interior surface  184  extends through the interior bore of the handle forward portion  144  from the first cylindrical interior surface  182  to the distal end surface  174  of the handle forward portion. 
         [0040]    The rod  12  of the instrument is secured in the interior bore of the handle forward portion  144  by the connection collar  112  being press fit into the first cylindrical interior surface  182  of the handle forward portion. This attaches the handle to the rod proximal end. Other equivalent means could be employed in securing the rod  12  in the interior bore of the handle forward portion  144 . Additionally, the handle could be on the rod as one monolithic piece with the rod or at least the rod  12  and the handle forward portion  144  could be made as a single monolithic piece. With the rod  12  secured in the interior bore of the handle forward portion  144 , the sliding surface  102  of the ring  92  mounted on the rod  12  is positioned radially inside and axially aligned with the distal end surface  174  of the handle forward portion  144 . 
         [0041]    A plurality of axially extending slots  186  are formed in the handle forward portion  144  at the distal end  148 . The axial slots  186  extend along the length of the handle forward portion  144  from the distal end surface  174  toward the proximal end  162  of the handle forward portion  144 . Each slot has a slot end  188  that is axially positioned where the handle forward portion first cylindrical interior surface  182  transitions to the second cylindrical interior surface  184 . The plurality of axial slots  186  form a plurality of resilient actuator arms  192  that are circumferentially spaced around the second cylindrical interior surface  184  of the handle forward portion interior bore. As seen in the drawing figures, each of the actuator arms  192  formed by the axial slots  186  has a radial width dimension that is smallest at the slot ends  188  or where the first cylindrical interior surface  182  of the handle forward portion interior bore transitions to the second cylindrical interior surface  184 . This gives the actuator arms  192  a radially deflecting resilience. The plurality of slots  186  form each of the actuator arms  192  with an interior surface defined by the second cylindrical interior surface  184  of the handle forward portion  144 , and an opposite exterior surface of the actuator arm defined by the exterior surface  170  of the handle forward portion  144 . In addition, each of the axial slots  186  defines opposite side surfaces of each actuator arm  192 . Each of the arm side surfaces have two planar surface portions  194 ,  196  that are positioned at an angle relative to each other. Radially inner surface portions  194  of each of the actuator arms  192  are substantially parallel to each other. The inner surface portions  194  of each arm  192  intersect or connect with the actuator arm interior surface defined by the second cylindrical interior surface  184  of the handle forward portion  144 . The radially outer surface portions  196  of each arm connect with and extend radially outwardly from the inner surface portions  194  and connect with the exterior surface  170  of the handle forward portion  144 . As the radial outer surface portions  196  extend radially outwardly from the inner surface portions  194  toward the exterior surface  170 , they merge toward each other. This configuration of the radially outer surface portions  196  increases the circumferential width dimension of the axial slots  186  adjacent the exterior surface  170  of the handle forward portion  144 . This increase in the circumferential width of the slots  186  adjacent the exterior surface  170  of the handle forward portion  144  prevents the surgeon&#39;s fingers from being pinched in the slots  186  between adjacent arms  192  when the arms  192  are pressed inwardly by the surgeon&#39;s fingers. 
         [0042]    The rounded, generally convex distal end surface  174  of the handle forward portion  144  is formed by the plurality of slots  186  into a plurality of free distal end surfaces on the plurality of actuator arms  192 . What is meant by free distal end surfaces is that the arms cantilever from the proximal end  162  of the handle forward position  144  to the free distal end surfaces  174  and there are no operative connections to the free distal end surfaces. In the at rest positions of the arms  192  the distal end surfaces are positioned in a common radial plane with the ring surface  102  and radially outwardly from and surrounding the ring surface  102 . When at least some of the arms  192  are pressed inwardly by the surgeon&#39;s fingers, the distal end surfaces  174  of the pressed arms engage in sliding engagement with the ring sliding surface  102 . In the preferred embodiment of the instrument, the distal end surfaces  174  of the actuator arms  192  are constructed of a material having a hardness that is less than the hardness of the ring sliding surface  102 . In this manner, the sliding movement of the actuator arm distal end surfaces  174  over the ring sliding surface  102  will not wear grooves in the ring sliding surface  102 . In addition, the distal end surfaces  174  on the actuator arms  192  could be separate surfaces added to the actuator arms  192 . However, in the preferred embodiment of the invention, the distal end surfaces  174  of the actuator arms  192  are surfaces of the arms. Furthermore, in other embodiments the distal end surfaces  179  could make point contact with the ring surface  102  to reduce sliding friction, or the end surfaces could have roller bearings or other equivalent structures that contact the ring surface  102 . 
         [0043]    With the construction of the microsurgical instrument  10  explained above, the instrument  10  can be comfortably held in the surgeon&#39;s hand with the reduced diameter intermediate portion of the instrument where the handle rearward portion  142  merges into the handle forward portion  144  positioned on the web of the hand between the thumb and forefinger. With the surgeon&#39;s fingertips gripping at least some of the actuator arms  192  of the handle forward portion  144 , manually compressing the arms  192  will cause the arm distal end surfaces  174  to contact the ring surface  102  and exert a compressive force on the sliding surface  102  of the ring  92 . This will cause the ring  92  to move axially over the rod  12  toward the rod distal end  16  and the second position of the ring  92  on the rod  12 . This in turn causes the ring bar  104  to move the microsurgical instrument tube  52  over the microsurgical instrument shaft  62 . This movement actuates the microsurgical instrument at the distal ends of the tube  52  and shaft  62 . In the example shown in the drawings, the microsurgical instrument is a microsurgical grasper  198 . In addition, the movement of the bar  104  compresses the spring  82 . 
         [0044]    Releasing the manual compressive force on the actuator arms  192  allows the resiliency of the arms  192  to move the arms back to their at rest positions and also releases the force on the ring  92  urging the ring toward the rod distal end  16 . This allows the compressed spring  82  to push the ring  92  over the rod  12  toward the rod proximal end  14  and the first position of the ring on the rod. The movement of the ring  92  could also cause the ring surface  102  to push the arms  192  radially outwardly to their at rest positions. This movement of the ring  92  on the rod  12  also causes the tube  52  to move relative to the shaft  62  and thereby opens the microsurgical surfaces of the grasper  198  formed at the end of the tube  52  and shaft  62 . 
         [0045]    In view of the foregoing, it will be seen that the several advantages of the invention are achieved and attained. 
         [0046]    As various modifications could be made in the construction of the surgical instrument of the invention herein described and illustrated without departing from the scope of the invention, it is intended that all matter contained in the foregoing description or shown in the accompanying drawings shall be interpreted as illustrative rather than limiting. Thus, the breadth and scope of the present invention should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims appended hereto and their equivalents.