Instrument, in particular medical-endoscopic instrument or technoscope

Abstract

Instrument, in particular a medical-endoscopic instrument or technoscope, with a shaft (2) and with an instrument head (10) arranged at the distal end of the shaft, which can be angled relative to the shaft (2) via a joint arranged between the shaft (2) and the instrument head (10) and which has a tool with two jaw parts (20, 22) which can be pivoted relative to one another and are each movement-coupled for control by two cables (70, 72, 76), wherein each of the cables (70, 72, 76) is guided in the region of the joint around a pair of deflection pulleys with two deflection pulleys (78, 80, 82, 84, 86, 88, 90, 92) arranged next to one another in the longitudinal direction of the instrument, characterized in that two pairs of deflection pulleys are arranged on either side of a central axis (A) of the instrument, of which the deflection pulleys (82, 84, 90, 92) of a first pair of deflection pulleys has a smaller diameter than the deflection pulleys (78, 80, 86,88) of a second pair of pulleys.

Description

[0001] The invention relates to an instrument and in particular to a medical-endoscopic instrument or technoscope having the features specified in the preamble of claim 1.

[0002] The invention is based on shaft instruments with an instrument head arranged at the distal end of the shaft, which can be angled relative to the shaft via a joint with one or more joint axes. A jaw tool with two jaw parts that can be pivoted relative to each other is provided on the distal side of the instrument head. Instruments of this type are used, among other things, as forceps, scissors, and the like in the field of minimally invasive surgery.

[0003] The cross-sectional dimensions of instruments used in minimally invasive surgery are particularly important. As a rule, there is a need to keep the shaft's cross-section as small as possible. This typically applies to all components of the instrument distal to the shaft, which, when the instrument head is aligned in a straight extension of the shaft, should not protrude beyond the shaft's cross-sectional contour.

[0004] Against this background, the object of the invention is to create an instrument of the type described above which meets this need for the smallest possible cross-sectional dimensions with a simple structural design of the instrument.

[0005] This object is achieved by an instrument having the features specified in claim 1. Advantageous developments of this instrument emerge from the subclaims, the following description, and the drawing. According to the invention, the subclaims, either individually or in meaningful combination with one another, can further develop the instrument according to claim 1.

[0006] The instrument according to the invention is preferably a medical-endoscopic instrument, which can be part of a robotic surgical system or a manually operated instrument. The instrument can also be a technoscope, which can be used in hard-to-reach cavities of technical objects. The instrument has an elongated, preferably straight and rigid shaft. An instrument head is arranged at the distal end of the shaft and can be angled relative to the shaft via a joint arranged between the shaft and the instrument head. The joint can be either a joint with a single joint axis or a double joint with two joint axes spaced apart from one another in the longitudinal direction of the instrument. The instrument head is equipped with two jaw parts that can be pivoted relative to one another.

[0007] To control the jaws, they are each motion-coupled by two cables. Each of these cables is expediently attached to an actuating disc that is motion-coupled to the jaw. The cables are attached and guided to the actuating discs in such a way that the cables act antagonistically on the jaw. This means that the two cables are connected to their respective associated actuating discs in such a way that one of the cables, when subjected to tensile stress, causes a pivoting movement of the jaw in a first direction, while the other cable counteracts the first cable and, when subjected to tensile stress, causes a countermovement or pivoting movement of the jaw in the opposite direction. The cables are guided through the shaft and are operatively connected to a control device on the proximal side of the shaft.Depending on the type of instrument, the control device is a control interface of a robotic system or a manually operated handle.

[0008] In the area of the joint connecting the instrument head to the shaft, the cables coupled to the jaws are each guided around a pair of pulleys. Each of these pulley pairs has two pulleys that are rotatably mounted at a distance from one another in the longitudinal direction of the instrument and aligned with one another in the circumferential direction. On each of the pulley pairs, one of the cables is guided in such a way that the respective cable wraps around the two pulleys of a pulley pair in an S-shaped manner. If the instrument head is connected to the shaft via a single joint with a joint axis, the cable intersects this joint axis. If the instrument head is connected to the shaft via a double joint with two spaced-apart joint axes, the cable is always guided essentially through the instantaneous center of angulation of the instrument head relative to the shaft.

[0009] According to the invention, two pairs of deflection pulleys are arranged on either side of a central axis of the instrument, i.e. on opposite outer sides of the central axis of the instrument. Of these two pairs of deflection pulleys, each arranged on an outer side of the central axis of the instrument, the deflection pulleys of a first pair of deflection pulleys have a smaller diameter than the deflection pulleys of a second pair of deflection pulleys. In this case, a distal deflection pulley of the first pair of deflection pulleys and a distal deflection pulley of the second pair of deflection pulleys expediently have a common axis of rotation oriented transversely to the longitudinal extent of the instrument, wherein a proximal deflection pulley of the first pair of deflection pulleys and a proximal deflection pulley of the second pair of deflection pulleys also have a common axis of rotation oriented transversely to the longitudinal extent of the instrument.Through this arrangement of the deflection pulleys of the two pairs of deflection pulleys arranged on the opposite outer sides of the central axis of the instrument and in particular through the different diameters of the deflection pulleys of the pairs of deflection pulleys, an arrangement of the deflection pulleys can be realized in which the only limited space available within the cross-sectional contour of the instrument can be used in an optimal way, which in turn makes it possible to keep the cross-sectional dimensions of the instrument comparatively small.

[0010] In this context, it proves to be particularly advantageous if, as provided in a first development of the instrument according to the invention, the first pairs of deflection pulleys, i.e. the pairs of deflection pulleys with the smaller diameter pulleys, are spaced further from the central axis of the instrument than the second pairs of deflection pulleys. This allows the pairs of deflection pulleys to be arranged at a relatively large distance from the central axis of the instrument without the deflection pulleys extending beyond the cross-sectional contour of the shaft. In an area around the central axis of the instrument, this creates a sufficiently large free space for the components of the instrument which serve to angle the instrument head relative to the shaft.

[0011] In order to be able to angle the instrument head relative to the shaft over the largest possible angular range, the instrument head is preferably connected to the shaft via a double joint. A double joint is understood to be a joint that has at least one joint part that can pivot about a pivot axis formed at the distal end of the shaft, which is referred to below as the proximal pivot axis, wherein on the distal side of the joint part the instrument head can be pivoted about a second pivot axis, referred to below as the distal pivot axis, which is aligned parallel to the proximal pivot axis. The instrument head can thus be angled relative to the shaft by an angle that is composed of the sum of the pivot angle of the joint part relative to the shaft and the pivot angle of the instrument part relative to the joint part.

[0012] In conjunction with a design in which the instrument head is connected to the shaft via a double joint, it is further advantageously provided that the instrument head can be angled via at least one rolling element pairing of a toothed rolling element arranged on the shaft side and a toothed rolling element on the instrument head side. Accordingly, at least one rolling element equipped with a toothing is arranged at the distal end of the shaft, which projects on the shaft in the direction of the instrument head, while at least one further toothed rolling element is arranged at the proximal end of the instrument head, which projects in the direction of the shaft and meshes with the rolling element arranged on the shaft. The aim of this design is to ensure a controlled angling of the instrument head relative to the shaft.

[0013] According to a further advantageous embodiment of the instrument according to the invention, the joint part connecting the instrument head to the shaft is articulated to a joint pin connected to the rolling element arranged on the shaft side and to a joint pin connected to the rolling element on the instrument head side. Accordingly, the joint pin connected to the rolling element on the shaft side forms the first, proximal pivot axis about which the joint part can be pivoted relative to the shaft, and the joint pin connected to the rolling element on the instrument head side forms the second, distal pivot axis about which the instrument head can be pivoted relative to the joint part and relative to the shaft.

[0014] Also advantageous in terms of space savings, the first and second pivot pins form the axes of rotation for the deflection rollers of the two pairs of deflection rollers, each arranged on the opposite outer sides of the instrument's central axis. This means that on the first pivot pin, connected to the rolling element arranged on the shaft side, the proximal deflection rollers of the two pairs of deflection rollers are rotatably mounted next to each other on both sides of the instrument's central axis, while on the second pivot pin, connected to the rolling element on the instrument head side, the distal deflection rollers of the two pairs of deflection rollers are rotatably mounted next to each other on both sides of the instrument's central axis.

[0015] Conveniently, a covering part is arranged on the outside of each of the outer pairs of deflection pulleys relative to the central axis of the instrument. This covering part, like the at least one joint part, is hinged to the two joint pins connected to the rolling elements and prevents the cables guided on the first, i.e., radially outer pairs of deflection pulleys from jumping off in a direction away from the central axis of the instrument.

[0016] When using a double joint to link the instrument head to the shaft, an actuating disc is preferably provided to angulate the instrument head, which is motion-coupled to a pair of cables and is positively connected to the rolling element on the instrument head via a sliding block. To accommodate the sliding block, an elongated hole is formed on both the rolling element arranged on the instrument head and on the actuating disc. The sliding block preferably forms a receiving space for the joint pin connected to the rolling element on the instrument head, which is guided through the sliding block. On the actuating disc, the two cables are guided circumferentially next to one another in the axial direction of the actuating disc, wherein they wrap around a distal end of the actuating disc in opposite directions.

[0017] Preferably, the actuating disc is arranged in a common plane with the central axis of the instrument. This arrangement is advantageous in that the actuating disc can have a particularly large diameter without protruding beyond the cross-sectional contour of the shaft. Due to the comparatively large radial dimensions of the actuating disc, particularly large actuating torques for bending the instrument head can be achieved.

[0018] According to a further advantageous embodiment of the instrument according to the invention, two deflection pulleys are arranged proximal to the actuating disc in the longitudinal direction of the instrument, one behind the other and expediently in alignment with the actuating disc. The cables of the pair of cables, with which the actuating disc is coupled for movement, are guided through a gap between the deflection pulleys. This guidance of the two cables, which are operatively connected to the actuating disc, enables particularly effective force transmission for angling the instrument head. Furthermore, this reduces the influence of disruptive forces acting on the instrument distally.

[0019] To ensure sufficient stability of the rolling element connection between the instrument head and the shaft, two rolling elements are preferably arranged on the shaft side, spaced apart from one another in a direction transverse to the central axis of the instrument, each of which engages with a rolling element on the instrument head side. In this embodiment, the actuating disc for angling the instrument head is preferably arranged in the space between the two rolling elements arranged on the shaft side and the two rolling elements on the instrument head side. The actuating disc is expediently rotatably mounted on a hinge pin that penetrates the rolling elements on the instrument head side in a direction transverse to the central axis of the instrument, which is also particularly space-saving.

[0020] Further preferably, a joint part is arranged on the outside of each of the rolling elements in the direction transverse to the central axis of the instrument. The two joint parts are pivotally connected to the joint pin, which is guided by the shaft-side rolling elements in the direction transverse to the central axis of the instrument, and to the second joint pin, which is guided by the instrument-head-side rolling elements in the direction transverse to the central axis of the instrument. Advantageously, the two joint pins radially overlap the adjacent rolling elements, thereby preventing tissue from becoming trapped between the meshing rolling elements.

[0021] The invention is explained in more detail below with reference to an exemplary embodiment illustrated in the drawing. The drawing shows, schematically simplified and at different scales: Fig. 1 a distal end of an instrument in perspective view, Fig. 2 the distal end of the instrument Fig. 1 in a opposite Fig. 1 perspective view rotated by 90°, Fig. 3 the instrument after Fig. 1 in a side view, Fig. 4 a sectional view along the section line IV-IV in Fig. 3, Fig. 5 the instrument after Fig. 1 in a second side view, Fig. 6 a sectional view along the section line VI-VI in Fig. 5, Fig. 7 the representation according to Fig. 1 if certain external components are omitted, Fig. 8 the representation according to Fig. 7 if other components are omitted, Fig. 9 in perspective view a tool carrier of an instrument head of the instrument according to Fig. 1, Fig. 10 in perspective view an actuating disc of an instrument head of the instrument according to Fig. 1, Fig. 11 in perspective view a slot nut for fastening the actuating disc according to Fig. 10 to the tool carrier after Fig. 9, Fig. 12 in perspective view a distal end piece of a shaft of the instrument according to Fig. 1, Fig. 13 in perspective view a jaw part of the instrument according to Fig. 1, Fig. 14 in a side view the instrument according to the Fig. 1 - 13 according to a second embodiment and Fig. 15 a sectional view along the section line XV-XV in Fig. 14.

[0022] The following explanations initially refer only to a Fig. 1 - 13. This instrument is a medical-endoscopic instrument in the form of forceps. This instrument, which can be a manually operated instrument or an instrument used in conjunction with a surgical robot, has an elongated, hollow-cylindrical shaft 2, whereby only the distal end of the shaft 2 is shown in the drawing for reasons of clarity. The control devices at the proximal end of the shaft 2, which in the case of a manually operated instrument are formed by a handle and in the case of an instrument that is part of a robotic surgical system, by a control interface of this system, are also not shown, since these are part of the prior art and are not the subject of the present invention.

[0023] An end piece 4 is arranged at the distal end of the shaft 2. As can be seen in particular from Fig. As can be seen in Figure 12, in which the end piece 4 is shown as an individual part, the end piece 4 has a substantially cylindrical base body 6, to which a cylindrical section 8 with a smaller diameter is connected on the proximal side. With the section 8, the end piece 4 engages in the distal end of the shaft 2, wherein the outer circumference of the section 8 contacts an inner wall of the shaft 2. In the contact area of the section 8 with the inner wall of the shaft 2, the end piece 4 is integrally connected to the shaft 2.

[0024] An instrument head 10 is arranged distally of the end piece 4. This instrument head 10 has a Fig. 9 as a single part, which can be angled via a double joint 14 about a proximal joint axis 16 and about a distal joint axis 18, which is aligned parallel to the joint axis 16 ( Fig. 1). The tool carrier 12 carries a jaw tool with two jaw parts 20 and 22 that can be pivoted relative to one another.

[0025] The end piece 4 arranged at the distal end of the shaft 2 has two projections 24 and 26 at its distal end, which project in the longitudinal extension of the shaft 2 and are spaced apart from one another in a direction transverse to the longitudinal orientation of the shaft 2. A through hole extending transversely to the longitudinal extent of the shaft 2 is formed on each of the projections 24 and 26, wherein the through holes of the two projections 24 and 26 are aligned with one another. The through holes serve to receive a hinge pin 28, which forms the proximal hinge axis 16 of the double joint 14 ( Fig. 1).

[0026] Corresponding to the two projections 24 and 26 formed on the end piece 4, two spaced-apart projections 30 and 32 are formed on the proximal end of the tool carrier 12, which extend in the proximal direction. A hinge pin 34 is also guided transversely to the longitudinal extent of the tool carrier 12 through the projections 30 and 32, which forms the distal hinge axis 18 of the double joint ( Fig. 1).

[0027] A joint part 36 is pivotally connected to the joint pins 28 and 34 forming the joint axes 16 and 18 on the outside of the projections 24 and 30. Similarly, a second joint part 38 is pivotally connected to the joint pins 28 and 34 on the outside of the projections 26 and 32. The joint parts 36 and 38 form part of the double joint 14 and connect the tool holder 12 to the shaft 2. The tool holder 12 can thus be angled relative to the shaft 2 in a plane normal to the joint axes 16 and 18, with its angle resulting from the sum of the angle of the joint parts 36 and 38 relative to the shaft 2 and the angle of the tool holder 12 relative to the joint parts 36 and 38.

[0028] To enable a defined angulation of the tool carrier 12 relative to the shaft 2, the end piece 4 of the shaft 2 and the tool carrier 12 are connected to one another via pairs of rolling elements. To form these pairs of rolling elements, the distal ends of the projections 24 and 26 formed on the end piece 4 and the proximal ends of the projections 30 and 32 formed on the tool carrier 12 each have a toothed section in the form of a gear segment, wherein the toothed sections formed on the projections 24 and 26 and the toothed sections formed on the projections 30 and 32, which have an identical pitch circle diameter, are in engagement with one another.

[0029] As is particularly evident from Fig. 9, the tool carrier 12 has an incision 40 on the distal side that is open towards the distal end of the tool carrier 12. The two jaw parts 20 and 22 of the jaw tool are hinged in this incision 40. For this purpose, the jaw part 20 has a storage section 42 on the proximal side and the jaw part 22 has a storage section 44 on the proximal side. A functional section 46 adjoins the storage section 42 of the jaw part 20. Correspondingly, a functional section 48 also adjoins the storage section 44 of the jaw part 22 on the distal side. The functional sections 46 and 48 of the jaw parts 20 and 22 are designed to grasp body tissue or objects. With their bearing sections 42 and 44, the jaw parts 20 and 22 engage side by side in the notch 40 formed on the tool carrier 12, where they are pivotally mounted on a pin 50.

[0030] A substantially circular actuating disk 52 is arranged on the tool carrier 12 in the space between the projections 30 and 32. For the positive connection of the actuating disk 52 to the tool carrier 12, an elongated hole 54 is formed on each of the projections 30 and 32 thereof, and an elongated hole 56 is formed on the actuating disk 52. The elongated holes 54 and 56 serve to receive a sliding block 58, via which the actuating disk 52 is fixed to the tool carrier 12. A through hole 60 is formed on the sliding block 58, through which the joint pin 34 forming the distal longitudinal axis 18 of the double joint 14 is passed. As can be seen from Fig. As can be seen in Figure 4, two cables 62 and 64 are attached to the actuating disc 52. To guide these cables 62 and 64, two guide grooves arranged next to one another in the axial direction of the actuating disc 52 are formed on the outer circumference of the actuating disc 52. Fig. 4 also shows that the cables 62 and 64 are guided antagonistically to the proximal end of the shaft 2 on two circumferential sections of the actuating disk 52 facing away from one another, so that a proximally directed tensile force exerted there on the cable 62 causes an angulation of the instrument head 10 in a first direction and the exertion of a proximally directed tensile force on the cable 64 causes a movement opposite to this angulation or an angulation of the instrument head 10 in a second direction.

[0031] On the proximal side of the actuating disc 52, a deflection pulley 66 is rotatably mounted in alignment with the actuating disc 52 to guide the cables 62 and 64 on the joint pin 28 forming the proximal joint axis 16 of the double joint 14. From the actuating disc 52, the cables 62 and 64 are guided in an S-shape through a space between the actuating disc 52 and the deflection pulley 66, so that the cables 62 and 64 come into contact with the deflection pulley 66 at circumferential sections facing away from one another. The actuating disc 52 and the deflection pulley 66 are dimensioned such that the cables 62 and 64 are each guided through the instantaneous center of the double joint 14, which ensures that the angulation of the instrument head 10 relative to the shaft 2 does not lead to an undesirable change in the length of the cables 62 and 64.

[0032] Fig. 6 shows that an area of the bearing section 42 of the jaw part 20 directly adjacent to the notch 40 of the tool carrier 12 forms an actuating disc 68 for fastening and guiding two cables 70 and 72. Fig. The cables 70 and 72 shown in Figure 5 serve to control the movement of the jaw part 20. They are guided on the actuating disk 68 in such a way that they wrap around the distal end of the actuating disk 68 in the opposite direction. An area of the bearing section 44 of the jaw part 22 adjacent to the notch 40 of the tool carrier 12 also forms an actuating disk 74 for fastening and guiding two cables, which serve to control the movement of the jaw part 22. For reasons of better clarity, only a few of these cables are shown in the drawing. Fig. 6 shows a cable pull 76. This cable pull 76 and the cable pull not shown are also guided on the actuating disc 74 in such a way that they wrap around the distal end of the actuating disc 74 in opposite directions.

[0033] From the actuating disc 68, the attached cables 70 and 72 are guided over the double joint 14 through the shaft 2 to the proximal side of the shaft 2, where they are motion-coupled to a control device. Correspondingly, the cable 76 attached to the actuating disc 74 and the cable (not shown) are guided over the double joint 14 through the shaft 2 to the proximal side of the shaft 2, where they are motion-coupled to a control device.

[0034] Each of the four cables used to control the movement of the jaw parts 20 and 22 is deflected in the area of the double joint on a pair of deflection pulleys assigned to it, with two pairs of deflection pulleys being provided on either side of a central axis A of the instrument. One of these pairs of deflection pulleys is formed by two deflection pulleys 78 and 80 with the same outer diameter, which are arranged directly outside the joint part 36. The deflection pulley 78 is rotatably mounted on the joint pin 34, while the deflection pulley 80, arranged proximal to the deflection pulley 78, is rotatably mounted on the joint pin 28. The cable pull 76, which is coupled in motion to the jaw part 22, is guided on the pair of pulleys formed by the pulleys 78 and 80 in such a way that it wraps around the pulleys 78 and 80 in an S-shape and is guided in the space between the pulleys 78 and 80 through the instantaneous center of the double joint 14.On the outside of the deflection pulley 78, a deflection pulley 82 is rotatably mounted on the hinge pin 34. This deflection pulley 78, together with a deflection pulley 84 rotatably mounted on the hinge pin 28 on the outside of the deflection pulley 80, forms another pair of deflection pulleys. The cable 70, which is coupled in motion to the jaw part 20, is guided on this pair of deflection pulleys in such a way that it wraps around the deflection pulleys 82 and 84 in an S-shape and is guided in the space between the deflection pulleys 82 and 84 through the instantaneous center of the double joint 14. The deflection pulleys 82 and 84 have an identical diameter, but are smaller than the diameter of the deflection pulleys 78 and 80.

[0035] Corresponding to the arrangement of the deflection pulleys 78, 80, 82 and 84 on the outside of the joint part 36, four further deflection pulleys 86, 88, 90 and 92 are arranged on the outside of the joint part 38. The deflection pulley 86 is rotatably mounted on the joint pin 34 directly on the outside of the joint part 38 and, together with the deflection pulley 88 rotatably mounted on the joint pin 28, forms a further pair of deflection pulleys on which the cable 72, which is coupled in movement to the jaw part 20, is guided in such a way that it wraps around the deflection pulleys 86 and 88 in an S-shape and is guided in the space between the deflection pulleys 78 and 80 through the instantaneous center of the double joint 14.Finally, the deflection pulleys 90, which are rotatably mounted on the hinge pin 34 on the outside of the deflection pulley 86, and the deflection pulley 92, which is rotatably mounted on the hinge pin 28 on the outside of the deflection pulley 88, form a pair of deflection pulleys for the cable pull (not shown in the drawing), which is coupled for movement to the jaw part 22. The cable pull (not shown) is guided on the pair of deflection pulleys formed by the deflection pulleys 90 and 92 in the same way as the cable pulley 72 is guided on the pair of deflection pulleys formed by the deflection pulleys 86 and 88. The deflection pulleys 90 and 92 also have a smaller diameter than the deflection pulleys 86 and 88.

[0036] The Fig. 14 and Fig. The instrument shown in Figure 15 differs from the one shown in Fig. 1 - 13 only with regard to the guidance of the cables 62 and 64 connected to the actuating disc 52. Here, proximal to the deflection roller 66 on the end piece 4 of the shaft 2, a further deflection roller 94 is rotatably mounted on a hinge pin 96 in alignment with the actuating disc 52 and the deflection roller 66. Unlike the Fig. 1 - 13 are shown in the instrument shown in the Fig. 14 and Fig. In the instrument shown in Figure 15, the cables 62 and 64 fixed to the actuating disc 52 are not guided through the space between the actuating disc 52 and the deflection pulley 66, but are guided in the opposite direction through the space between the deflection pulleys 66 and 94. List of reference symbols 2 shaft 4 end piece 6 basic bodies Section 8 10 Instrument head 12 tool carriers 14 double joint 16 Joint axis 18 Joint axis 20 jaw part 22 Jaw part 24 lead 26 lead 28 hinge pin 30 lead 32 lead 34 hinge pin 36 Joint part 38 Joint part 40 incision 42 Storage section 44 Storage section 46 Functional section 48 Functional section 50 pens 52 Actuating disc 54 slot 56 slot 58 T-slot nut 60 through hole 62 cable pull 64 cable pull 66 pulley 68 Actuating disc 70 cable pull 72 cable pull 74 Actuating disc 76 cable pull 78 pulley 80 pulley 82 pulley 84 pulley 86 pulley 88 pulley 90 pulley 92 pulley 94 pulley 96 hinge pin A central axis

Claims

[1] Instrument, in particular a medical-endoscopic instrument or technoscope, with a shaft (2) and with an instrument head (10) arranged at the distal end of the shaft, which can be angled relative to the shaft (2) via a joint arranged between the shaft (2) and the instrument head (10) and which has a tool with two jaw parts (20, 22) which can be pivoted relative to one another and are each movement-coupled for control by two cables (70, 72, 76), each of the cables (70, 72, 76) being guided in the region of the joint around a pair of deflection pulleys with two deflection pulleys (78, 80, 82, 84, 86, 88, 90, 92) arranged next to one another in the longitudinal direction of the instrument, characterized bythat two pairs of deflection pulleys are arranged on each side of a central axis (A) of the instrument, of which the deflection pulleys (82, 84, 90, 92) of a first pair of deflection pulleys have a smaller diameter than the deflection pulleys (78, 80, 86, 88) of a second pair of deflection pulleys. [2] Instrument according to claim 1, characterized by that the first pairs of pulleys are spaced further from the central axis (A) of the instrument than the second pairs of pulleys. [3] Instrument according to one of the preceding claims, characterized by that the instrument head (10) is connected to the shaft (2) via a double joint (14). [4] Instrument according to claim 3, characterized by that the instrument head (10) can be angled via at least one rolling element pairing of a toothed rolling element arranged on the shaft side with a toothed rolling element on the instrument head side. [5] Instrument according to claim 4, characterized bythat at least one joint part (36, 38) connecting the instrument head (10) to the shaft (2) is articulated on a joint pin (28) connected to the rolling body arranged on the shaft side and a joint pin (34) connected to the rolling body on the instrument head side. [6] Instrument according to claim 5, characterized by that the first and second hinge pins (28, 34) form axes of rotation for the deflection rollers of the deflection roller pairs. [7] Instrument according to one of the preceding claims, characterized by that a covering part is arranged on the outside of the outer pair of deflection pulleys relative to the central axis (A) of the instrument. [8] Instrument according to one of claims 5 to 7, characterized by that an actuating disc (52) which is coupled in movement to a pair of cables is positively connected to the rolling element on the instrument head side via a sliding block (58). [9] Instrument according to claim 8, characterized bythat the actuating disc (52) is arranged in a common plane with the central axis (A) of the instrument head (10). [10] Instrument according to one of claims 8 or 9, characterized by that two deflection rollers (66, 94) are arranged one behind the other on the proximal side of the actuating disc (52) in the longitudinal direction of the instrument, wherein the cables (62, 64) of the cable pair, which is coupled in movement to the actuating disc (52), are guided through an intermediate space between the deflection rollers (66, 94). [11] Instrument according to one of claims 4 to 10, characterized by that on the shaft side there are two rolling elements spaced apart from one another in a direction transverse to the central axis of the instrument head (10), each of which engages with a rolling element on the instrument head side. [12] Instrument according to claim 11, characterized bythat the actuating disc (52) is arranged in a space between the two rolling elements arranged on the shaft side and the two rolling elements arranged on the instrument head side. [13] Instrument according to one of claims 11 or 12, characterized by that in the direction transverse to the central axis of the instrument, a joint part (36, 38) is arranged on the outside of the rolling elements, which joint part radially covers the rolling elements.

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