Endoscopic Instrument and Shaft and Insert for Endoscopic Instrument

Abstract

An endoscopic instrument is disclosed that includes an elongate shaft and an instrument insert releasably connected to a distal end portion of the shaft, the distal end portion of the shaft being in the form of a sleeve and a proximal end region of a base of the instrument insert being in the form of a coupling shaft, or the distal end portion of the shaft being in the form of a coupling shaft and a proximal end region of a base of the instrument insert being in the form of a sleeve, with the coupling shaft being releasably held in the sleeve and the sleeve and/or the coupling shaft at least in portions having a cross-sectional profile which is reversibly changeable for detaching the coupling shaft from the sleeve. The invention also relates to a shaft for an endoscopic instrument, and to an instrument insert for an endoscopic instrument.

Claims

1. An endoscopic instrument having an elongate shaft and an instrument insert releasably connected to a distal end portion of the shaft, the distal end portion of the shaft being in the form of a sleeve and a proximal end region of a base of the instrument insert being in the form of a coupling shaft, or the distal end portion of the shaft being in the form of a coupling shaft and a proximal end region of a base of the instrument insert being in the form of a sleeve, with the coupling shaft being releasably held in the sleeve, wherein the sleeve and/or the coupling shaft at least in portions have a cross-sectional profile which is reversibly changeable for detaching the coupling shaft from the sleeve.

2. The endoscopic instrument of claim 1, wherein the cross-sectional profile is reversibly changeable by an elastic deformation of the sleeve or coupling shaft for the purposes of detaching the coupling shaft from the sleeve.

3. The endoscopic instrument of claim 1, wherein the cross-sectional profile is a substantially closed cross-sectional profile.

4. The endoscopic instrument of claim 2, wherein the sleeve comprises a first holding structure and the coupling shaft comprises a second holding structure, the sleeve and/or the coupling shaft being convertible by reversible deformation from a respective work shape, in which the first holding structure is arranged with the second holding structure for holding the coupling shaft in the sleeve, to a respective assembly shape, in which the first holding structure and the second holding structure are arranged separate from one another.

5. The endoscopic instrument of claim 4, wherein the first and/or the second holding structure extends in the circumferential direction over one or more partial angular ranges of the sleeve or of the coupling shaft, and wherein the sleeve comprises at least one pressure point situated outside of the partial angular ranges, for deforming the cross-sectional profile of the sleeve.

6. The endoscopic instrument of claim 5, wherein the work shape of the sleeve is a flattened shape, with a respective pressure point being arranged in the vertices of the flattened shape, and/or the assembly shape of the sleeve is a flattened shape, with a respective pressure point being arranged between the vertices in the circumferential direction.

7. The endoscopic instrument of claim 5, wherein the sleeve has three pressure points, which are each offset by approximately 120° from one another.

8. The endoscopic instrument of claim 7, wherein the coupling shaft has a support portion for supporting an end portion of the sleeve in the work shape.

9. The endoscopic instrument of claim 4, wherein the first holding structure is an engagement structure and the second holding structure is an engagement element embodied to engage in the first holding structure, or vice versa.

10. The endoscopic instrument of claim 9, wherein the second holding structure comprises a radially protruding stud and the first holding structure has a corresponding cut-out in which the stud engages.

11. The endoscopic instrument of claim 10, wherein the first and the second holding structure interact to hold the coupling shaft in the sleeve so as to be secured against rotation.

12. The endoscopic instrument of claim 4, wherein, the first and/or the second holding structure has or have an oblique shoulder in a circumferential direction, on one side or on both.

13. The endoscopic instrument of claim 1, wherein the coupling shaft has a resilient lug with a detent that engages in a cut-out of the sleeve.

14. The endoscopic instrument of claim 1, wherein, in the axial direction, the first and/or the second holding structure has an oblique shoulder in an insertion direction.

15. The endoscopic instrument of claim 1, wherein the first and the second holding structures comprise interacting friction surfaces and/or are designed for micro-teeth.

16. The endoscopic instrument of claim 1, wherein the sleeve and/or the coupling shaft at least partly consist of metallic glass.

17. The endoscopic instrument of claim 1, wherein the cross-sectional profile for detaching the coupling shaft from the sleeve is changeable under the action of temperature.

18. A shaft for an endoscopic instrument, the shaft having an elongate form, wherein a distal end portion of the shaft is in the form of a sleeve or a coupling shaft, the sleeve or the coupling shaft at least in portions having a reversibly deformable cross-sectional profile.

19. An instrument insert for an endoscopic instrument, the instrument insert comprising a tool and a base, wherein a proximal end region of the base of the instrument insert is in the form of a sleeve or coupling shaft, the sleeve or the coupling shaft at least in portions having a reversibly deformable cross-sectional profile.

20. The instrument insert of claim 19, wherein the cross-sectional profile is reversibly changeable by an elastic deformation of the sleeve or coupling shaft for the purposes of detaching the coupling shaft from the sleeve

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Further aspects of the invention emerge from the following description of preferred exemplary embodiments and the attached drawing, in which:

[0051] FIG. 1 shows a side view of an endoscopic instrument according to an embodiment of the present invention;

[0052] FIG. 2 shows a partial view of an endoscopic instrument according to a further embodiment of the invention;

[0053] FIG. 3 shows the distal end region of the shaft of the instrument according to FIG. 2 with an instrument insert detached from the shaft;

[0054] FIGS. 4a to 4c show the distal end region of the shaft of the instrument according to FIG. 2 with an inserted instrument insert with open and closed couplings in different representations;

[0055] FIG. 5 shows a schematic representation of the distal end region of the shaft with instrument insert according to FIG. 4b in the longitudinal section, with indicated cross sections;

[0056] FIGS. 6a and 6b show two variants of the exemplary embodiment according to FIG. 2;

[0057] FIG. 7 shows a symbolic representation of the mode of action of the coupling according to one exemplary embodiment of the invention; and

[0058] FIGS. 8a to 8c show a schematic representation of the mode of action of the coupling according to a further exemplary embodiment of the invention.

DETAILED DESCRIPTION OF THE REPRESENTATIVE EMBODIMENTS

[0059] As illustrated in FIG. 1, a medical endoscopic instrument 1, according to an exemplary embodiment of the present invention, comprises a shaft 2 and an instrument insert 10. The shaft 2 comprises a proximal portion 3, an elongate central portion 4 and a distal end portion 5. The shaft 2 is dimensioned for insertion into a body-internal cavity, for example for insertion into a work channel of an endoscope which is introduced into the body-internal cavity during an endoscopic intervention. The proximal portion 3 of the shaft 2 may for example comprise a rinsing connector 6 and a connecting mechanism 7 for a connection to a handle not illustrated here. By means of the connecting mechanism 7, the handle can be connected to the shaft 2 so as to be rotatable or so as to be secured against rotation.

[0060] A tool 11 is arranged at the distal end portion 5 of the shaft 2 and is formed in the illustrated exemplary embodiment as a pair of scissors with two scissor blades 12, 12′ that are pivotable relative to the distal end portion 5 of the shaft 2. The tool 11 is part of the instrument insert 10, which is inserted into the shaft 2 at the distal side. The instrument insert 10 furthermore comprises a base 13, formed on the distal side as a fork, in which the scissor blades 12, 12′ are mounted in pivotable fashion. By way of a coupling shaft, the base 13 is inserted into the distal end portion 5 of the shaft 2 and connected to the latter, for the purposes of which the distal end portion 5 is formed as a sleeve as explained in exemplary fashion below.

[0061] A connecting rod 14 is arranged within the shaft 2 so as to be displaceable in the longitudinal direction of the shaft 10. The proximal end of the connecting rod 14 is formed by a connecting element, for example a ball 15, which can be connected to a movable part of the handle (not depicted here) for the purposes of displacing said connecting rod 14 in the longitudinal direction by actuating the movable part of the handle. The connecting rod 14 can transmit both tensile and shearing forces in the longitudinal direction of the shaft 10. The connecting rod 14 is connected to the scissor blades 12, 12′ in articulated fashion and likewise forms a part of the instrument insert 10. The scissor blades 12, 12′ can be opened or closed by displacing the connecting rod 14 in the proximal or distal direction. The shaft 2 is in the form of a metallic shaft tube which is enclosed by an electrically insulating jacket 8. By way of example, electrical connectors for RF voltage may be arranged on the handle or on the shaft 2.

[0062] FIG. 2 shows a shaft 2 according to a further exemplary embodiment of the invention in a partial view seen obliquely from the distal direction. As indicated in FIG. 2, the central portion 4 of the shaft is formed by a metal shaft tube 9; the jacket 8 (see FIG. 1) is not depicted. The distal end portion 5 of the shaft 2 is designed as a sleeve 20, which forms part of a coupling for detachably connecting the instrument insert 10 to the shaft 2. The sleeve 20 has two transverse slots 21, 21′ which are arranged opposite one another and each extend in the circumferential direction, of these, only the upper transverse slot 21 is visible in FIGS. 2 and 3. The terms “above” and “horizontal” and “vertical” relate here and below to the relative position of the instrument depicted in the figures, the endoscopic instrument being able to adopt any other relative position when in use.

[0063] The sleeve 20 is elastically deformable at least in the region of the transverse slots 21, 21′ such that the sleeve can adopt different cross-sectional shapes as a result of an external application of force in the radial direction. Consequently, the sleeve 20 has an elastically deformable cross-sectional profile in the region of the transverse slots 21, 21′. The sleeve 20 has an assembly shape in the left-hand image of FIGS. 2 and 3 while it has a work shape in the right-hand image of FIGS. 2 and 3. On the proximal side, the sleeve 20 is securely connected to the shaft tube 9 or can be formed in one piece with the shaft tube 9 such that an external contour of the shaft tube 9 merges smoothly into that of the sleeve 20.

[0064] In the proximal portion, the sleeve 20 has a largely unchanging cross-sectional form that approximately corresponds to the, e.g., circular or oval cross section of the shaft tube 9. However, the sleeve 20 is elastically deformable in the region of the transverse slots 21, 21′ and to the distal side of the transverse slots 21, 21′ and, if there is no external application of force, adopts the work shape or is elastically pretensioned into the work shape. As is evident in FIG. 3 at the distal end surface 22 of the sleeve 20, the work shape (right-hand image of the sleeve 20) is circular or a horizontal oval, that is to say has a horizontally directed semimajor axis, in the depicted example. As a result of the external application of force in the radial direction on surface regions, only one of which being visible in FIGS. 2 and 3, that are opposite one another in the horizontal direction, said surface regions being offset by approximately 90° in relation to the center of the transverse slots 21, 21′ in the circumferential direction and being referred to here as pressure points 23, 23′, the sleeve 20 can be deformed in such a way that it adopts the assembly shape which is a vertical oval in the illustrated example, that is to say has a vertically directed semimajor axis (left-hand image of the sleeve 20). The sleeve 20 is preferably produced from metallic glass, which facilitates both great durability and high elasticity.

[0065] The instrument insert 10 has a tool 11 which is in the form of grasping forceps in the depicted example, which comprise a stationary jaw part 16, which is securely connected to the base 13 of the tool, and a movable jaw part 16′, which is articulated on the base 13 in pivotable fashion. A proximal end region of the base 13 is designed as a coupling shaft 17, arranged at the proximal end of which there are two studs 18, 18′ opposite one another in the vertical direction, said studs each protruding beyond the surface of the coupling shaft 17 in the radial direction. The instrument insert 10 further comprises a connecting rod, not depicted, which is guided through the coupling shaft 17 and the base 13 and which is connected to the movable jaw part 16′ and which is dimensioned for insertion into the shaft 2 of the endoscopic instrument 1 up to the proximal end thereof.

[0066] The studs 18, 18′ are formed in a manner corresponding to the transverse slots 21, 21′ of the sleeve 20 such that the studs 18, 18′ can engage in the transverse slots 21, 21′ when the sleeve 20 has the work shape (right-hand image in FIGS. 2 and 3, with the stud 18 engaging in the transverse slot 21 being depicted in exaggerated fashion in the right-hand image in FIG. 2). Then again, in the assembly shape of the sleeve 20 (left-hand image of the shaft 2 in FIGS. 2 and 3), the vertical internal width of the sleeve 20 in the region of the transverse slots 21, 21′ is greater than the diameter, measured in the vertical direction, of the engagement structure formed by the two studs 18, 18′, that is to say greater than the vertical distance between the outer sides of the studs 18, 18′; therefore, the studs 18, 18′ can no longer both simultaneously engage in the transverse slots 21, 21′ in the assembly shape.

[0067] If the sleeve 20 is brought into the assembly shape by way of lateral pressure on the pressure points 23, 23′ and if it is kept in said shape, the coupling shaft 17 can be inserted into the sleeve 20 until the studs 18, 18′ are level with the transverse slots 21, 21′ in the axial direction. If necessary, the studs 18, 18′ can be brought into the angle positions corresponding to the transverse slots 21, 21′ by way of a rotation of the coupling shaft 17 about its longitudinal axis. Then, the transverse slots 21, 21′ are only still lifted off the studs 18, 18′ in the radial direction. If the lateral application of force is subsequently terminated, the studs 18, 18′ engage in the transverse slots 21, 21′. In this state, the coupling shaft 17 and hence the instrument insert 10 is securely held at the distal end of the shaft 2. As a result of the design of the transverse slots 21, 21′ and the studs 18, 18′, optionally additionally in conjunction with the base 13 resting against the distal end face 22 of the sleeve, an axial play can be restricted or avoided, just as this can optionally bring about a connection secured against rotation. As a result of renewed lateral pressure on the pressure points 23, 23′, the sleeve 20 can be converted back into the assembly shape so that the sleeve 20 is lifted off the studs 18, 18′ in the region of the transverse slots 21, 21′ and the coupling shaft 17 can be pulled out of the sleeve 20 in the axial direction.

[0068] As is evident from FIGS. 2 and 3, a longitudinal axis 19 of the base 13 and the coupling shaft 17 is flush with a longitudinal axis 24 of the shaft 2 and the sleeve 20 in the assembled state, and the tool 11 is arranged on a distal-side continuation of the shaft 2.

[0069] In FIGS. 4a and 4b, the coupling formed by the coupling shaft 17 and the sleeve 20 is shown in an open and closed state, respectively, in each case in a vertical longitudinal section. FIG. 4a shows that the coupling shaft 17 is inserted in the sleeve 20. In the case of the axially directed insertion movement, the sleeve 20 is widened in the vertical direction by way of proximal-side oblique shoulders 31, 31′ of the studs 18, 18′. This simplifies the insertion of the coupling shaft 17 into the sleeve 20; additionally, a lateral compressive force can be exerted on the pressure points 23, 23′ for the purposes of reaching and maintaining the assembly shape (see above). In the state shown in FIG. 4a, the coupling shaft 17 has been inserted so far into the sleeve 20 in the axial direction that a step 30 of the base 13 rests against the distal end face 22 of the sleeve 20. In this position, the studs 18, 18′ are arranged radially within the transverse slots 21, 21′. FIG. 4a depicts the sleeve 20 in the assembly shape, in which the studs 18, 18′ do not yet engage in the transverse slots 21, 21′.

[0070] FIG. 4b shows the sleeve 20 in the work shape, which the sleeve 20 assumes after reaching the position shown in FIG. 4a as a result of elastic restoring forces and optionally as a result of the discontinuation of the lateral compressive force. In the work shape, the studs 18, 18′ engage in the transverse slots 21, 21′ and the sleeve 20, by way of regions adjoining the transverse slots 21, 21′ at the distal side, engages in the undercut formed by a distal-side step 32, 32′ of the studs 18, 18′. As a result, the coupling shaft 17 and hence the base 13 of the instrument insert 10 is securely held on the shaft 2. In particular, an axial position of the base 13 relative to the shaft 2 is defined by the step 30 of the base 13, which acts as a stop, and the distal side of the studs 18, 18′. Further, a rotational position of the base 13 relative to the shaft 2 can be defined by the extent of the studs 18, 18′ in the circumferential direction in conjunction with a corresponding extent of the transverse slots 21, 21′.

[0071] As is likewise evident in FIG. 4b, the sleeve 20 rests against the coupling shaft 17 in the vertical direction by means of an engagement portion, in particular at the distal end. As a result, this can achieve a connection of the base 13 to the shaft 2 that is rigid against corresponding bending loads. The base 13 with the coupling shaft 17 and also the sleeve 20 and the shaft tube 9 form an interior space 25 that is continuous in the longitudinal direction, the connecting rod, not depicted here, by means of which the tool 11 can be actuated, being guided therethrough. The shaft tube 9 has a greater wall strength than the sleeve 20 but an external contour that transitions smoothly into the external contour of the sleeve. The sleeve 20 can be formed in one part with the shaft tube 9.

[0072] FIG. 4c shows a partly cut oblique view of the coupling in the closed state. As is evident from FIG. 4c, a cavity 40 is present in the region of the pressure point 23 between an external surface of the coupling shaft 17 and an inner surface of the sleeve 20, said cavity being present to allow the sleeve 20 to be pressed together sufficiently so that the studs 18, 18′ can be detached from the transverse slots 21, 21′. A corresponding cavity is also present on the opposite side of the cross section that is not visible in FIG. 4c. In this exemplary embodiment, the coupling has a rigid form against a bending load in the horizontal direction by virtue of the distal end face 22 of the sleeve resting against the step 30 of the base 13 and being held by the distal-side step 32, 32′ of the studs 18, 18′, which each rest against the distal side of the relevant transverse slot 21, 21′; to this end, the relevant portions of the sleeve 20 and of the coupling shaft 17 are matched to one another with tight tolerance in respect of their length. The connecting rod and the mechanism for pivoting the movable jaw part 16′ are not depicted in FIG. 4c.

[0073] FIG. 5 shows a simplified schematic representation of the coupling in the closed state, that is to say corresponding to FIG. 4b, likewise in a vertical longitudinal section, with a plurality of cross sections being indicated for elucidation purposes. In the closed state of the coupling, in which the cross-sectional shape of the sleeve 20 is the work shape, the sleeve 20 with its regions adjoining the transverse slots 21, 21′ on the distal side engages into the undercut formed by the distal-side step 32, 32′ of the studs 18, 18′, and the studs 18, 18′ engage in the transverse slots 21, 21′ (see FIGS. 4a and 4b). As indicated symbolically in FIG. 5, the sleeve 20 in the work shape has a horizontal oval cross section 26 in the region of the transverse slots 21, 21′. The shaft tube 9 which adjoins the sleeve 20 on the proximal side has a circular cross section 27. The base 13 likewise has a circular cross section 33.

[0074] FIGS. 6a and 6b depict two variants of the exemplary embodiment described above, in each case in a partly transparent view. In the variant shown in FIG. 6a, the coupling shaft 17 has been extended in the proximal direction such that the latter protrudes through the sleeve 20 and into the shaft 9 in the closed state of the coupling. The proximal-side extension 41 of the coupling shaft 17 rests against the inner side of the shaft 9 with tight tolerances or without play. As a result, additional rigidity can be imparted on the coupling, especially in the horizontal direction as well.

[0075] In the variant depicted in FIG. 6b, the coupling shaft 17 has a support portion 42 on the distal side of the step 30 of the base 13, said support portion having a cross-sectional profile that is matched to the internal contour of the sleeve 20 in the work shape and rests against the latter without play. The support portion 42 only has a short longitudinal extent so as not to impede a deformation of the sleeve 20 for the purposes of detaching the studs 18, 18′ from the transverse slots 21, 21′. Increased rigidity in the horizontal direction can also be attained in this way, the actuation profile 42 being able to represent an additional anti-twist device between the shaft 9 and the base 13.

[0076] Opening the coupling is depicted symbolically by means of cross-sectional contours in FIG. 7. In the closed state (left-hand image), the cross-sectional contour 28 of the sleeve 20 is flattened in such a way in the region of a holding structure that the latter engages in an undercut of the coupling shaft 17, which is depicted with a circular cross-sectional contour 34. As a result of pressure from both sides (force F) on the pressure points 23, 23′, which correspond to the vertices of the horizontal oval cross-sectional shape, the cross-sectional profile in the intervening circumferential regions can be spread in the direction of the arrows 39, 39′ and hence the flattening of the cross section can be reduced (central image), until finally the holding structure of the sleeve is lifted out of the undercut of the coupling shaft 17 and the coupling is open (right-hand image).

[0077] In a further exemplary embodiment of the invention, which is depicted schematically in FIGS. 8a to 8c, the coupling shaft 17 has a cross section which approximately has the shape of an equilateral triangle, the corners of the triangle being formed as studs 18, 18′, 18″ which, in the work shape, each engage in cut-outs 29, 29′, 29″ of the sleeve 20 that are in each case offset from one another by 120° in the circumferential direction. The coupling shaft 17 has such a deformable cross-sectional profile that the studs 18, 18′, 18″ can be pressed inward. The coupling can be released by virtue of a manual force F being exerted on the studs 18, 18′, 18″, in each case in the direction of the arrows, such that the coupling shaft 17 is converted into the assembly shape in which the studs 18, 18′, 18″ no longer engage in the cut-outs 29, 29′, 29″ and the coupling shaft 17 can be pulled out of the sleeve 20 in the axial direction (not depicted here). As in the exemplary embodiments described above, a force F of the order of one or a few N, for example approximately 5 N, may be sufficient for this here.

[0078] In the exemplary embodiment shown in FIG. 8a, the studs 18, 18′, 18″ each have, on both sides, oblique shoulders 35 in the circumferential direction. As an alternative or in addition to the manual application of the lateral compressive force, this provides the option of twisting the sleeve 20 relative to the coupling shaft 17 about the longitudinal axis, as a result of which the studs 18, 18′, 18″ are pressed-in in the radial direction by way of the respective oblique shoulders 35, and as a result likewise lose engagement with the cut-outs 29, 29′, 29″. The coupling can also be released thereby.

[0079] Further, alternatively or in addition, provision can be made for the sleeve 20 to have a deformable cross-sectional profile. In this case, the sleeve 20 can be deformed by a lateral application of force on pressure points, which are located between the cut-outs 29, 29′, 29″ in the circumferential direction, and by a rotation of the sleeve 20 relative to the coupling shaft 17 such that the studs 18, 18′, 18″ are detached from the cut-outs 29, 29′, 29″ (not depicted here).

[0080] According to a variant of the embodiment shown in FIG. 8a, the base 13 or the coupling shaft 17 further comprises a resilient lug 36 which carries a detent 37, which engages in a cut-out 38 of the sleeve 20 when the coupling is closed and which has no oblique shoulders in the circumferential direction (see FIGS. 8b, 8c). This therefore serves as an anti-twist device to prevent an inadvertent release of the coupling as a result of a torque that occurs when the instrument is used. Therefore, to release the coupling in this variant, the detent 37 must be pressed in by the application of a radial force F′ in order to subsequently twist the coupling shaft 17 about the longitudinal axis relative to the sleeve 20.

[0081] For the sake of clarity, not all reference signs are shown in all of the figures. Reference signs not explained in connection with one figure have the same meaning as in the other figures.

[0082] Although the invention and its advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the scope of the invention as defined by the appended claims. The combinations of features described herein should not be interpreted to be limiting, and the features herein may be used in any working combination or sub-combination according to the invention. This description should therefore be interpreted as providing written support, under U.S. patent law and any relevant foreign patent laws, for any working combination or some sub-combination of the features herein. Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described in the specification. As one of ordinary skill in the art will readily appreciate from the disclosure of the invention, processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized according to the invention. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps.

LIST OF REFERENCE SIGNS

[0083] 1 Instrument [0084] 2 Shaft [0085] 3 Proximal portion [0086] 4 Central portion [0087] 5 Distal end portion [0088] 6 Rinsing connector [0089] 7 Connecting mechanism [0090] 8 Jacket [0091] 9 Shaft tube [0092] 10 Instrument insert [0093] 11 Tool [0094] 12, 12′ Scissor blade [0095] 13 Base [0096] 14 Connecting rod [0097] 15 Ball [0098] 16, 16′ Jaw part [0099] 17 Coupling shaft [0100] 18, 18′, 18″ Stud [0101] 19 Longitudinal axis [0102] 20 Sleeve [0103] 21, 21′ Transverse slot [0104] 22 End face [0105] 23, 23′ Pressure point [0106] 24 Longitudinal axis [0107] 25 Interior space [0108] 26 Cross section [0109] 27 Cross section [0110] 28 Cross-sectional contour [0111] 29, 29′, 29″ Cut-out [0112] 30 Step [0113] 31, 31′ Oblique shoulder [0114] 32, 32′ Step [0115] 33 Cross section [0116] 34 Cross-sectional contour [0117] 35 Oblique shoulder [0118] 36 Lug [0119] 37 Detent [0120] 38 Cut-out [0121] 39, 39′ Arrow [0122] 40 Cavity [0123] 41 Extension [0124] 42 Support portion [0125] F, F′ Force