fig1 shows a schematic axonometric view of a distal end 12 of a medical instrument 10 for micro - invasive applications in human or veterinary medicine . the medical instrument 10 has a long , thin , rigid or flexible ( i . e . elastically deformable , or plastically deformable without destruction ), straight or curved shank 20 . the distal of the shank 20 is mechanically connected to a tool 30 , in particular to the proximal end 34 thereof , in such a way as to be releasable without destruction . a manipulation mechanism for manually manipulating the medical instrument 10 can be provided at the proximal end of the shank 20 . the tool 30 comprises two branches 32 which are pivotable in opposite directions about the same pivot axis and which serve for the gripping , pinching , electrosurgical coagulation or cutting of tissue . the tool 30 comprises a first component or fork component 40 and a second component or catch component 50 . the fork component 40 comprises two parallel side rails 41 , of which the distal ends 42 form the distal end of the fork component 40 . a bearing 43 for the pivotable branches 32 is provided at the distal ends 42 of the side rails 41 . the bearing 43 is formed by a shaft connecting the distal ends 42 of the side rails 41 . the shaft defines the common pivot axis of the pivotable branches 32 . the proximal end of the fork component 40 is formed by a substantially circular proximal edge 44 of the fork component 40 . the proximal edge 44 of the fork component 40 is interrupted by two slits 48 arranged opposite each other , of which only one is visible in fig1 . the slits 48 each have a substantially rectangular shape . the catch component 50 comprises an annular area 54 , which is arranged parallel to the proximal edge 44 of the fork component 40 and can be joined thereto , in particular connected thereto by welding . the catch component 50 moreover comprises two catches which lie opposite each other and of which the radially outer ends or areas 58 fill the slits 48 at the proximal end of the fork component 40 and are joined thereto . in particular , the edges of the radially outer areas 58 of the catches of the catch component 50 are connected to the edges of the slits 48 by welding or soldering . a transmission mechanism is arranged in the shank 20 and in the fork component 40 of the tool 30 , which transmission mechanism , in the view in fig1 , is largely concealed by the shank 20 and the fork component 40 of the tool 30 . only an endpiece 62 forming the distal end of the transmission mechanism is partially visible in fig1 between the side rails 41 of the fork component 40 of the tool 30 . the transmission mechanism is displaceable within a predetermined range inside the shank 20 and the fork component 40 of the tool 30 in a direction parallel to the longitudinal axis of the shank 20 . the proximal end of the transmission mechanism is coupled , for example , to a pivotable part of said manipulation mechanism at the proximal end of the shank 20 . the endpiece 62 forming the distal end of the transmission mechanism is coupled in an articulated manner to the branches 32 , in each case via a connecting rod 36 , in such a way that a translational movement of the transmission mechanism is associated with a pivoting movement of the branches 32 of the tool 30 . fig2 shows a schematic axonometric view of the tool 30 from fig1 . the nature of the view , in particular the viewing direction , substantially corresponds to that of fig1 . only the tool 30 is shown in fig2 , not the shank 20 of the medical instrument . therefore , a further part of the transmission mechanism 60 is visible in fig2 , namely a rod 70 that is provided for arrangement in the shank 20 of the medical instrument 10 ( cf . fig1 ). moreover , the annular structure of the annular area 54 and a cavity 46 in the fork component 40 can be seen in fig2 . fig3 shows a schematic axonometric view of constituent parts of the shank 20 of the medical instrument 10 from fig1 . the nature of the view , in particular the viewing direction , substantially corresponds to that of fig1 and 2 . the shank comprises a shank tube 24 , of which the position in fig3 in the horizontal direction corresponds to the position in fig1 . two l - shaped slits arranged opposite each other are provided at the distal end 22 of the shank tube 24 , of which only one slit is visible in fig3 . each l - shaped slit comprises a first portion 25 , which extends parallel to the longitudinal axis 28 of the shank tube 24 , and a second portion 26 , which extends in a direction parallel to the circumference of the shank tube 24 . fig3 moreover shows a support tube 80 which , when the shank has been made ready for use in the intended manner , is arranged at the distal end 22 of the shank inside the shank tube 24 . in fig3 , the support tube 80 is shown outside the shank tube 24 , i . e . having been withdrawn in the distal direction from the shank tube 24 in a direction parallel to the longitudinal axis 28 of the shank . with the shank made ready for use in the intended manner , the support tube 80 is arranged in the shank tube 24 particularly in such a way that the distal edge of the support tube 80 and the distal edge of the shank tube 24 lie in one plane . the support tube 80 has two straight slits 86 which are each rectangular or substantially rectangular and which lie opposite each other , of which only one slit is visible in fig3 . the slits 86 are parallel to the longitudinal axis 28 of the shank and therefore also parallel to the intended direction of movement of the transmission mechanism 60 ( cf . fig2 ). in the intended arrangement of the support tube 80 in the shank tube 24 , the slits 86 in the support tube 80 , on the one hand , and the first portions 25 of the l - shaped slits in the shank tube 24 , on the other hand , are congruent or substantially congruent . when the shank 20 has been made ready , the support tube 80 is connected to the shank tube 24 in particular by cohesive bonding ( for example by laser welding or soldering ) and optionally in addition with frictional engagement or force - fit engagement . the support tube 80 reinforces the distal end 22 of the shank . moreover , the inner cross section of the support tube 80 ( apart from the slits 86 ) corresponds substantially to the outer cross section of the rod 70 of the transmission mechanism 60 ( cf . fig2 ), such that the transmission mechanism 60 is guided in the support tube 80 with minimal play and friction . moreover , the outer cross section of the shank tube 24 and therefore of the shank corresponds at the distal end 22 thereof ( apart from the l - shaped slits 25 , 26 ) to the cross section of the cavity 46 ( apart from the catches ) at the proximal end of the fork component 40 ( cf . fig2 and 6 ), such that the distal end 22 of the shank 20 is guided with minimal play in the cavity 46 in the fork component 40 . fig4 shows a further schematic axonometric view of parts of the tool 30 from fig2 . the nature of the view , in particular the viewing direction , substantially corresponds to that of fig1 and 2 . in fig4 , the tool 30 is shown without the catch component 50 . the slits 48 in the fork component 40 are therefore visible , which slits 48 start from the substantially circular proximal edge 44 of the fork component 40 and interrupt said edge . fig5 shows a further schematic axonometric view of the tool 30 from fig2 and 4 . the nature of the view , in particular the viewing direction , substantially corresponds to that of fig1 and 4 . in fig5 , the fork component 40 of the tool 30 is depicted in transparent form and is indicated only by the contours thereof that are visible in the chosen viewing direction . therefore , the catches 56 arranged in the distal direction from the annular area 54 of the catch component 50 are visible in fig5 , their outer ends or areas 58 filling the slits 48 in the fork component 40 ( cf . fig4 ). the radially inner ends of the catches 56 extend into the cavity 46 at the proximal end of the fork component 40 ( cf . fig4 ). moreover , the transmission mechanism 60 is largely visible in fig5 . the transmission mechanism 60 comprises a rod 70 and an endpiece 62 , which forms the distal end of the transmission mechanism 60 . the endpiece 62 comprises a distal end 64 with a bearing for the articulated connection to the connecting rods 36 , and a substantially thin and plate - shaped proximal end 66 , which is arranged in a slit at the distal end 72 of the rod 70 . edges of the thin plate - shaped proximal end 66 of the endpiece 62 that protrude laterally from the slit at the distal end 72 of the rod 70 form two web - shaped locking projections 68 . the locking projections 68 each extend parallel to the longitudinal axis of the rod 70 of the transmission mechanism 60 and thus also parallel to the longitudinal axis 28 of the shank 20 ( cf . fig3 ) and to the slits 86 in the support tube 80 . fig6 shows a schematic view of the catch component 50 as seen from the distal direction . for orientation purposes , the contour of the cross section of the rod 70 of the transmission mechanism 60 ( cf . fig5 ) is also indicated by a broken line . the inner contour of the annular area 54 of the catch component 50 corresponds to the contour of the cross section of the cavity 46 at the proximal end of the fork component 40 ( cf . fig2 and 4 ). the catches 56 engage from outside in the cavity 46 . the widths of the catches 56 correspond to the widths of the first portions 25 of the l - shaped slits in the shank tube 24 , such that the catches can be guided with minimal friction through the first portions 25 of the l - shaped slits in the shank tube 24 . if the catches 56 engage so deeply in the cavity 46 that they also engage in the slits 86 in the support tube 80 ( cf . fig3 ), the slits 86 in the support tube 80 are also at least as wide as the catches 56 and , in contrast to the view in fig3 , are l - shaped . the lengths of the catches ( each measured in a direction parallel to the longitudinal axis 28 of the shank ; cf . fig3 ) correspond to the dimensions of the second portions 26 of the l - shaped slits in the shank tube 24 , such that the catches 56 can be inserted with minimal friction into the second portions 26 of the l - shaped slits . fig7 shows a further schematic axonometric view of constituent parts of the transmission mechanism 60 of the tool 30 from fig1 and 2 . in fig7 , the endpiece 62 is shown in a position offset distally in relation to the rod 70 . therefore , fig7 clearly shows , on the one hand , the slit 74 at the distal end 72 of the rod 70 , and , on the other hand , the thin plate - shaped proximal end 66 of the endpiece 62 . the lateral edges of the proximal end 66 of the endpiece 62 , which extend parallel to the longitudinal axis of the rod 70 , form the locking projections 68 . in the example shown , the locking projections 68 have rounded cross sections . fig8 shows a schematic view of the fork component 40 of the tool 30 from fig1 and 2 , as seen from the distal direction . between the proximal ends of the side rails 41 , on the one hand , and the distal end of the cavity 46 ( cf . fig4 ), on the other hand , the fork component 40 has a wall 45 , which is not visible in the other figures . this wall 45 is in particular substantially plate - shaped and flat and delimits the cavity 46 in the distal direction or forms the distal surface of the cavity 46 . a continuous bore 47 is provided in the wall 45 . the continuous bore 47 extends , in the axial direction of the fork component 40 and thus in a direction orthogonal with respect to the drawing plane of fig9 , from the space between the side rails 41 , on the one hand , to the cavity 46 at the proximal end of the fork component 40 ( cf . fig2 and 4 ; not visible in fig9 ), on the other hand . the continuous bore 47 has a cross section corresponding substantially to the cross section of the transmission mechanism 60 in the transition area between the endpiece 62 and the rod 70 ( cf . fig5 and 7 ), such that the transmission mechanism 60 is guided in the continuous bore 47 in the fork component 40 with minimal play and friction . the cross section of the transmission mechanism 60 in the transition area between the endpiece 62 and the rod 70 ( cf . fig5 and 7 ) and the cross section of the continuous bore 47 are each non - circular . in particular , the cross section of the transmission mechanism 60 deviates from a purely circular shape as a result of the locking projections 68 ( cf . fig5 ). in this way , a rotation of the transmission mechanism 60 relative to the fork component 40 is suppressed by form - fit engagement . fig9 shows a further schematic view of the fork component 40 of the tool 30 from fig1 and 2 . in fig9 , the fork component 40 is shown in a view from the proximal direction . thus , the fork component 40 is shown from opposite directions in fig8 and 9 . fig9 shows the continuous bore 47 , the substantially circularly cylindrical cavity 46 at the proximal end of the fork component 40 , and the two slits 48 lying opposite each other in the fork component 40 . the contours of the catches 56 protruding into the cavity 46 , and belonging to the catch component 50 ( cf . fig1 , 5 and 6 ), not shown in fig9 , are indicated by broken lines . as has already been mentioned , the transmission mechanism 60 is guided in the fork component 40 ( cf . fig8 and 9 ) by form - fit engagement between the transition area between the rod 70 and the endpiece 62 , in particular the locking projections 68 , on the one hand , ( cf . fig5 and 7 ), and the continuous bore 47 in the fork component 40 , on the other hand , in such a way that the transmission mechanism 60 can be displaced in the longitudinal direction relative to the fork component 40 but cannot be rotated . alternatively , a similar guide can be achieved by form - fit engagement between the connecting rods 36 , the distal end 64 of the endpiece 62 of the transmission mechanism 60 and the mutually facing surfaces of the side rails 41 of the fork component 40 ( cf . fig2 and 4 ). the function of the components of the tool 30 and of the shank 20 will be clear from the overview of the figures . for the releasable mechanical connection of the tool 30 to the shank 20 , the transmission mechanism 60 , in particular the rod 70 of the transmission mechanism 60 ( cf . fig2 ), is first of all inserted into the shank 20 ( cf . fig3 ) from the distal direction . the branches 32 of the tool 30 are brought to a beyond open position , in which the angle between the branches 32 is greater than that shown in fig1 , 4 and 5 . in this beyond open position , the locking projections 68 on the transmission mechanism 60 assume their farthest distal position , in which they engage in the continuous bore 47 in the fork component 40 but do not protrude into the cavity 46 at the proximal end of the fork component 40 . the shank 20 and the tool 30 are brought together until the distal end 22 of the shank 20 is inserted completely into the cavity 46 in the fork component 40 of the tool 30 and the distal end 22 of the shank 20 bears on the wall 45 of the fork component 40 . the catches 56 are thereby inserted into the first portions 25 of the l - shaped slits at the distal end 22 of the shank 20 . when the distal end 22 of the shank 20 bears on the wall 45 in the fork component 40 , the catches 56 are located in the transition areas between the first portions 25 and the second portions 26 of the l - shaped slits at the distal end 22 of the shank tube 24 ( cf . fig3 ). the shank 20 can now be rotated clockwise ( viewed from the proximal direction ) about its axis 28 relative to the tool 30 . in doing so , the catches 56 are moved away from the first portions 25 into the second portions 26 of the l - shaped slits at the distal end 22 of the shank 20 . when the catches 56 bear on the ends , remote from the first portions 25 , of the second portions 26 of the l - shaped slits at the distal end 22 of the shank 20 , shank 20 and tool 30 are located in their intended relative positions , in which shank 20 and tool 30 cannot be separated from each other by a simple translational movement . in this intended position of the shank 20 relative to the tool 30 , the locking projections 68 on the transmission mechanism 60 ( cf . fig5 ) are aligned with the slits 86 in the support tube 80 and with the first portions 25 of the l - shaped slits at the distal end 22 of the shank tube 24 ( cf . fig3 ). the transmission mechanism 60 can therefore be moved in the proximal direction relative to the tool 30 and to the shank 20 , whereupon the branches 32 leave their beyond open position . in doing so , the locking projections 68 on the transmission mechanism 60 engage in the slits 86 in the support tube 80 and the first portions 25 of the l - shaped slits in the shank tube 24 . by means of this engagement , the tool 30 can no longer be rotated relative to the shank 20 , and the catches 56 cannot be moved to the first portions 25 of the l - shaped slits in the shank tube 24 . in this way , the mechanical connection between shank 20 and tool 30 is locked as long as the branches 32 are not located in their beyond open position . a movement to the beyond open position 32 can be suppressed by mechanisms at the distal ends of the shank 20 and of the transmission mechanism 60 , in particular in a manipulation mechanism . in the ideal case free of play , the distal edge or the distal end 22 of the shank tube 24 ( cf . fig3 ) bears on the wall 45 in the fork component 40 ( cf . fig8 and 9 ), on the one hand , while at the same time , on the other hand , the distal ends or edges of the catches 56 ( cf . fig5 ) bear on the distal edges of the second portions 26 of the l - shaped slits in the shank tube 24 ( cf . fig3 ). a longitudinal play of the mechanical connection between shank 20 and tool 30 is defined by the difference between the distance of the distal edges or flanks of the catches 56 ( cf . fig5 ) and the wall 45 in the fork component 40 ( cf . fig8 and 9 ), on the one hand , and the distance between the distal edges of the second portions 26 of the l - shaped slits in the shank tube 24 and the distal end 22 of the shank tube 24 , on the other hand . in fig1 and 2 , a small distance is indicated between the annular area 54 of the catch component 50 , on the one hand , and the proximal edge 44 of the fork component 40 , on the other hand . this small distance can be bridged or filled by a welded or soldered seam . in other words , the dimensions of the two catches 56 measured in a direction parallel to the longitudinal axis 28 of the shank 20 are slightly greater than the depths , measured in the same direction , of the slits 48 in the fork component . this ensures that , when the catches 56 are pushed into the slits 48 , the positions of the catches 56 are defined unambiguously , with a form fit , by the abutment of the catches 56 or of their outer areas 58 against the distal ends of the slits 48 in the fork component 40 . in these positions defined unambiguously by a form - fit engagement , the outer areas 58 of the catches 56 are joined to the slits 48 or to the edges of the slits 48 , in particular connected thereto by laser welding . the distances defining the mechanical play between shank 20 and tool 30 are therefore each defined on a single component . on the shank 20 , this is the distance between the distal edge or end 22 of the shank tube 24 and the distal edge of the second portion 26 of the l - shaped slit in the shank tube 24 . on the tool , this is the distance between the proximal surface of the wall 45 in the fork component 40 and the distal ends of the slits 48 in the fork component , on which the distal end faces of the outer areas 58 of the catches 56 bear . since both distances determining the play are each defined on a single component , the play can be set particularly precisely and , consequently , can also be particularly small . for the non - destructive release of the mechanical connection between shank 20 and tool 30 , a blocking of the beyond open position can optionally be canceled first of all via the manipulation mechanism . thereafter , the branches 32 are moved to their beyond open position and the transmission mechanism 60 is moved with the locking projections 68 to its farthest distal position . in this configuration , the locking projections 68 on the transmission mechanism 60 ( cf . fig5 ) no longer engage in the slits 86 in the support tube 80 and in the first portions 25 of the l - shaped slits in the shank tube 24 ( cf . figure ). the tool 30 can be rotated counterclockwise ( viewed from the distal direction ) relative to the shank 20 . in doing so , the catches 56 engaging from the outside in the second portions 26 are moved as far as the transition areas between the second portions 26 and the first portions 25 of the l - shaped slits in the shank tube 24 . thereafter , shank 20 and tool 30 can be pulled apart from each other . in doing so , the catches 56 are moved into the first portions 25 of the l - shaped slits in the shank tube 24 and are pulled out of the latter . the invention being thus described , it will be obvious that the same may be varied in many ways . such variations are not to be regarded as a departure from the spirit and scope of the invention , and all such modifications as would be obvious to one skilled in the art are to be included within the scope of the following claims .
a tool for a dismantlable medical instrument includes a first component , which surrounds a cavity for receiving a distal end of a shank , and a second component with a catch , which protrudes into the cavity surrounded by the first component to form a bayonet connection with a distal end of a shank protruding into the cavity , by engagement of the catch in a slit or a groove at the distal end of the shank . the first component has a recess into which the second component is fitted .