Cannula nerve retractor for separating, exposing and protecting nervous tissue

Abstract

The utility model belongs to the technical field of medical instruments, particularly relates to a cannula nerve retractor for separating, exposing and protecting nervous tissues, and aims to solve the problems that an existing retractor cannot ensure high efficiency and stability of separating, retaining and retracting ligamentum flavum and nerve retraction during operation and cannot be visually operated during use. According to the scheme, the device comprises an outer sleeve and a plurality of front-end protection heads; the front end of the outer sleeve is movably connected with a replaceable front end protection head, an observation window is arranged on the same side of the front end protection head, the front end of an inclined opening of the front end protection head is connected with a retraction sheet, and the retraction sheet connected with each front end protection head is provided with different outward inclination angles. The protective head is provided with the observation window and is connected with the retraction sheets with different outward deflection angles, the front ends of the retraction sheets are provided with protective rolling edges, the protective head can be rapidly replaced and reliably fixed, clear sound and tactile feedback are provided in the screwing process, and the safety and efficiency of the spine endoscopic surgery are remarkably improved.

Description

Technical Field

[0001] This utility model relates to a cannula nerve retractor, specifically a cannula nerve retractor used for separating, exposing, and protecting nerve tissue, belonging to the field of medical device technology. Background Technology

[0002] Spinal endoscopic minimally invasive surgery, a significant advancement in spinal surgery in recent years, has gained widespread clinical application due to its advantages of minimal trauma, less bleeding, and faster recovery, particularly in the treatment of lumbar disc herniation and spinal stenosis, where it has become a mainstream technique. Single-channel spinal endoscopy, which utilizes a single working channel for both observation and surgical manipulation, places higher demands on instrument design and surgical skills. During the procedure, it is crucial to retract and protect sensitive tissues such as nerve roots and the dural sac while providing sufficient space for surgical manipulation; this is a key factor for surgical success. Traditional spinal endoscopic surgery with nerve-protecting retractors has several limitations: insufficient retraction stability, leading to easy displacement and nerve exposure; limited working space, affecting the efficiency of surgical instrument operation; and low visualization, making it difficult for the surgeon to monitor nerve status in real time.

[0003] While existing technologies have explored various neuroprotective device designs, such as the minimally invasive unilateral dual-channel endoscopic fixation semi-tube neuroprotective sheath disclosed in CN221229366U, which includes: a pull plate, a positioning element fixedly disposed at the distal end of the pull plate, a handle fixedly disposed at the proximal end of the pull plate, and a limiting hook fixedly disposed at the proximal end of the handle; wherein, the positioning element includes: a measuring part fixedly disposed at the distal end of the pull plate, and a positioning part fixedly disposed at the distal end of the measuring part; several scale lines are provided on the wall surface of the measuring part away from the handle; the pull plate of this utility model's protective sheath is an arc-shaped semi-tube, which better protects the nerves in the spine; and by providing the positioning element, the scale lines on the positioning element allow medical personnel to accurately and clearly know the depth of the protective sheath inserted into the intervertebral space, and assist in measuring the height of the intervertebral space, facilitating... The subsequent implantation of the fusion device utilizes an arc-shaped semi-tube design to protect the nerve and includes a positioning device with graduated lines to measure the insertion depth. While this design improves protection, it still suffers from insufficient adjustment flexibility. It cannot flexibly adjust the retraction angle and range according to the actual situation during the operation, and it lacks real-time visualization monitoring, preventing the surgeon from directly observing the nerve status. Another example is the unilateral dual-channel endoscopic technique for assisted interbody fusion device placement with a cannula and hook disclosed in announcement number CN210019457U. This technique combines the cannula with the hook and places a protective plate at the cannula's tip to protect nerve tissue. While this design provides some nerve protection, its high degree of structural integration makes it difficult to adapt to different patients' anatomical characteristics and surgical needs. Furthermore, it cannot provide real-time feedback on the nerve status during the operation. Utility Model Content

[0004] This invention provides a cannula nerve retractor for separating, exposing, and protecting nerve tissue, addressing the problems of existing retractors failing to ensure the stability of nerve retraction during operation and the inability to visualize the operation.

[0005] The present invention achieves the above objectives through the following technical solution: a cannula nerve retractor for separating and exposing protected nerve tissue, comprising an outer cannula, the front end of which is movably connected to a front protective head;

[0006] The front protective head has an observation window. The front end of the inclined opening of the front protective head is connected to a pull-out piece. There are multiple front protective heads, and the pull-out piece connected to each front protective head has a different outward tilt angle. The outer wall of the front end of the pull-out piece is connected to a rolled edge.

[0007] The outer tube has a docking outer tube at its front end, and a docking sleeve is connected to the inner end of the docking outer tube. The upper end of the front protective head is connected to the docking inner tube. The docking inner tube and the docking sleeve are threadedly connected. There are multiple sets of limiting ring units between the docking outer tube and the docking sleeve. Each set of limiting ring units is elastically provided with multiple limiting blocks. In the initial state, the docking sleeve is frictionally fixed to the docking outer tube. After the docking inner tube and the docking sleeve are threadedly tightened, the docking sleeve can be rotatably connected relative to the docking outer tube.

[0008] As a further improvement of this utility model: an endoscope is movably inserted inside the outer tube, and a tiny gap is formed between the endoscope's tube and the inner wall of the outer tube.

[0009] As a further improvement of this utility model, a handrail is connected to the upper end of the outer tube.

[0010] As a further improvement of this utility model, the outward tilt angle of the pull-out piece connected to the front protective head includes 0°, 4° or 7.5°.

[0011] As a further improvement of this utility model: an external threaded ring is provided on the outer wall of the inner tube, and an internal threaded ring is provided on the inner wall of the sleeve, and the external threaded ring and the internal threaded ring are threadedly connected.

[0012] As a further embodiment of this utility model: the limiting ring unit includes an inner limiting protrusion, a limiting concave ring, and an outer limiting protrusion. The inner limiting protrusion is connected to the inner wall of the docking outer tube, the limiting concave ring is opened on the outer wall of the docking outer tube, and the inner limiting protrusion is located on the upper and lower sides of the limiting concave ring. The outer limiting protrusion is connected to the outer wall of the docking sleeve, and the outer limiting protrusion is locked in the limiting concave ring. It should be noted that the upper and lower sides of the connection between the outer limiting protrusion and the outer wall of the docking sleeve are provided with annular inner grooves, and the inner limiting protrusion is locked in the annular inner grooves.

[0013] As a further embodiment of this utility model: a locking block placement groove is provided on the outer limiting protruding ring, a spring is placed in the locking block placement groove, a limiting groove is provided on the inner wall of the limiting concave ring, the upper end of the limiting locking block is locked in the limiting groove, the lower end of the limiting locking block is locked in the locking block placement groove, and the spring abuts against the bottom end of the limiting locking block.

[0014] As a further embodiment of this utility model: one side of the inner wall of the limiting groove is an outwardly inclined slope, one side of the upper part of the limiting block is an inclined slope, and the inclined block of the upper part of the limiting block is in close contact with the inclined inner wall of the limiting groove.

[0015] As a further improvement of this utility model: the inner wall of the outer tube is provided with an internal friction surface, and the outer wall of the sleeve is provided with an external friction surface.

[0016] The beneficial effects of this utility model are:

[0017] 1. This utility model is equipped with an outer tube, and the front end of the outer tube is movably connected to a front protective head. Through the outer tube, the separation and collaborative work of the core operating instrument and the external working channel are realized. The detachable front protective head allows the surgeon to replace the front protective head with a retraction plate with a different angle at any time according to the surgical process and exposure requirements, which greatly enhances the adaptability and flexibility of the surgery.

[0018] 2. The front protective head of this utility model is provided with an observation window. The front end of the inclined opening of the front protective head is connected to a retraction piece. There are multiple front protective heads, and the retraction piece connected to each front protective head has a different outward tilt angle. The outer wall of the front end of the retraction piece is connected with a rolled edge. The observation window provides the surgeon with a direct visual channel, which is convenient for real-time observation of the state of the retracted nerve root or ligamentum flavum and other tissues during the operation, so as to adjust the retraction force and position in time, which significantly improves the safety of the operation. The rolled edge at the front end of the retraction piece is rounded, which can effectively prevent the nerve tissue from being damaged due to contact with the sharp edge of the instrument during the retraction process, and at the same time greatly reduces the risk of nerve tissue being dislodged from the retraction area.

[0019] 3. The outer sleeve of this utility model has a connecting outer tube at its front end, and a connecting sleeve is connected to the inner end of the connecting outer tube. The upper end of the front protective head is connected to a connecting inner tube, which is threadedly connected to the connecting sleeve. Multiple sets of limiting ring units are provided between the connecting outer tube and the connecting sleeve, and each set of limiting ring units has multiple limiting blocks elastically provided. In the initial state, the connecting sleeve is frictionally fixed to the connecting outer tube. After the connecting inner tube and the connecting sleeve are screwed together, the connecting sleeve can be rotated relative to the connecting outer tube. The threaded connection between the connecting inner tube and the connecting sleeve ensures a firm connection. The initial frictional connection between the connecting sleeve and the connecting outer tube is achieved through multiple sets of limiting retaining ring units and limiting blocks. When replacing the front protective head, the connecting inner tube on it is screwed onto the connecting sleeve located on the outer tube by rotation. After the thread is tightened, the rotational force is continued to overcome the static friction between the connecting sleeve and the connecting outer tube, causing the connecting sleeve to rotate relative to the connecting outer tube. At this time, the elastically set limiting blocks will make a "click" sound during elastic movement, providing the operator with clear auditory and tactile feedback, indicating that the front protective head has been rotated into place and locked. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the connection structure between the outer tube and the front protective head of the pull-out piece, which is folded outward at 0°.

[0021] Figure 2 This is a schematic diagram of the connection structure between the outer tube and the front protective head of the present invention, which is folded outward by 4° to the pull-out piece.

[0022] Figure 3 This is a schematic diagram of the connection structure between the outer sleeve and the front protective head of the present invention, which is folded outward by 7.5°.

[0023] Figure 4 This is a schematic diagram of the front-end protective head structure of this utility model;

[0024] Figure 5 This is a schematic diagram of the structure of the outer sleeve of this utility model used in conjunction with an endoscope;

[0025] Figure 6 This is a schematic diagram of the cross-sectional structure of the bottom end of the outer sleeve of this utility model;

[0026] Figure 7 This utility model Figure 6 Schematic diagram of the structure at point A in the middle;

[0027] Figure 8 This is a schematic diagram of the disassembled structure of the connecting sleeve and the connecting outer tube of this utility model;

[0028] Figure 9 This is a partial structural diagram of the limiting ring unit of this utility model in a disassembled state;

[0029] Figure 10 This is a schematic diagram of the structure of the limiting block and the limiting groove of this utility model in a disassembled state.

[0030] In the diagram: 1. Endoscope; 2. Outer tube; 21. Handrail; 22. Front protective head; 23. Retraction plate; 24. Observation window; 25. Rolled edge; 26. Connecting inner tube; 27. External threaded ring; 28. Connecting sleeve; 29. ​​Internal threaded ring; 210. Connecting outer tube; 211. Inner limiting protrusion ring; 212. Limiting concave ring; 213. Limiting groove; 214. Outer limiting protrusion ring; 215. Limiting block; 216. Block mounting groove; 217. Spring; 218. Inner friction surface; 219. Outer friction surface. Detailed Implementation

[0031] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0032] Example 1

[0033] like Figures 1 to 10 As shown, a cannula nerve retractor for separating and exposing protected nerve tissue includes an outer tube 2, with a front protective head 22 movably connected to the front end of the outer tube 2. Through the outer tube 2, the separation and coordinated operation of the core operating instrument and the external working channel are realized. The detachable design of the front protective head 22 allows the surgeon to replace the front protective head 22 with different angle retraction plates 23 at any time according to the surgical progress and exposure requirements, which greatly enhances the adaptability and flexibility of the surgery.

[0034] The front protective head 22 has an observation window 24. The front end of the inclined opening of the front protective head 22 is connected to a retraction piece 23. There are multiple front protective heads 22, and the retraction piece 23 connected to each front protective head 22 has a different outward tilt angle. The outer wall of the front end of the retraction piece 23 is connected to a rolled edge 25. The observation window 24 provides the surgeon with a direct visual channel, which is convenient for real-time observation of the state of the retracted nerve root or ligamentum flavum and other tissues during the operation, so as to adjust the retraction force and position in time, significantly improving the safety of the operation. The rolled edge 25 at the front end of the retraction piece 23 is smooth, which can effectively prevent the nerve tissue from being damaged due to contact with the sharp edge of the instrument during the retraction process, and at the same time greatly reduce the risk of nerve tissue being dislodged from the retraction area.

[0035] The outer sleeve 2 has a docking outer tube 210 at its front end, and a docking sleeve 28 is connected to the inner end of the docking outer tube 210. The upper end of the front protective head 22 is connected to a docking inner tube 26. The docking inner tube 26 and the docking sleeve 28 are threadedly connected. Multiple sets of limiting retaining ring units are provided between the docking outer tube 210 and the docking sleeve 28, and each set of limiting retaining ring units is elastically provided with multiple limiting retaining blocks 215. In the initial state, the docking sleeve 28 is frictionally fixedly connected to the docking outer tube 210. After the docking inner tube 26 and the docking sleeve 28 are threadedly tightened, the docking sleeve 28 can be rotatably connected relative to the docking outer tube 210. The docking inner tube 26 and the docking sleeve 28 are connected by threads, ensuring the connection. For robustness, the docking sleeve 28 and the docking outer tube 210 are initially fixed by friction through multiple sets of limiting ring units and limiting blocks 215. When replacing the front protective head 22, the docking inner tube 26 on it is screwed into the docking sleeve 28 located on the outer tube 2 by rotation. After the thread is tightened, the rotational force is continued to be applied. This force will overcome the static friction between the docking sleeve 28 and the docking outer tube 210, causing the docking sleeve 28 to rotate relative to the docking outer tube 210. At this time, the elastically set limiting blocks 215 will make a "click" sound during the elastic movement, providing the operator with clear auditory and tactile feedback, indicating that the front protective head 22 has been rotated into place and locked.

[0036] Example 2

[0037] Improvements based on Example 1:

[0038] like Figure 5 As shown, an endoscope 1 is movably inserted inside the outer sheath 2, and a tiny gap is formed between the tube of the endoscope 1 and the inner wall of the outer sheath 2. Based on the endoscope device disclosed in CN1676090A, which mentions setting the gap on one side between the tube body and the insertion part of the sheath to 0.5mm to 1.5mm, in this embodiment, the tiny gap between the tube of the endoscope 1 and the inner wall of the outer sheath 2 is in the range of 0.5mm to 1.5mm. It should be noted that medical instruments used in minimally invasive endoscopic surgery, such as an inner sheath, can also be movably inserted inside the outer sheath 2 to ensure that the outer sheath 2 can be used in conjunction with the endoscope 1 and the inner sheath, etc., without affecting the use of conventional instruments under the endoscope, which facilitates surgical operations near nerves.

[0039] like Figures 1 to 4 , Figures 6 to 10 As shown, the upper end of the outer tube 2 is connected to a handrail 21. The handrail 21 allows the surgeon to hold the outer tube 2 comfortably and securely, facilitating fine adjustments during the operation, such as lifting, pressing down, or slightly rotating it, to optimize the position and angle of the working channel, thereby obtaining the best surgical field of vision and operating space, and improving the accuracy and safety of the surgical operation.

[0040] Furthermore, the outward tilt angle of the retraction flap 23 connected to the front protective head 22 includes 0°, 4°, or 7.5°. The retraction flap 23 with a 0° angle can provide basic, parallel retraction function; the outward tilt angles of 4° and 7.5° can gradually increase the distance between the retracted tissue such as nerve tissue or ligamentum flavum and the central axis of the cannula, thereby creating a more spacious triangular working area at the end of the instrument. The surgeon can choose to install the front protective head 22 at different angles according to the specific stage of the surgery, the target location, and the area to be exposed, which greatly enhances the versatility of the instrument and the adaptability of the surgery.

[0041] Furthermore, the outer wall of the inner tube 26 is provided with an external threaded ring 27, and the inner wall of the sleeve 28 is provided with an internal threaded ring 29. The external threaded ring 27 and the internal threaded ring 29 are threadedly connected. Through the threaded connection between the external threaded ring 27 and the internal threaded ring 29, it can be ensured that the front protective head 22 is tightly connected to the sleeve 28 on the outer tube 2 via the inner tube 26. This can withstand the axial force and torsional force that may be generated during the operation, preventing it from loosening or falling off accidentally during the operation. This ensures the integrity and stability of the overall structure of the instrument. At the same time, the threaded connection is also easy to operate. The surgeon can complete the installation or removal with a simple rotation action, meeting the need for rapid replacement during the operation.

[0042] Furthermore, the limiting ring unit includes an inner limiting protrusion 211, a limiting concave ring 212, and an outer limiting protrusion 214. The inner limiting protrusion 211 is connected to the inner wall of the docking outer tube 210, the limiting concave ring 212 is formed on the outer wall of the docking outer tube 210, and the inner limiting protrusion 211 is located on the upper and lower sides of the limiting concave ring 212. The outer limiting protrusion 214 is connected to the outer wall of the docking sleeve 28, and the outer limiting protrusion 214 is engaged within the limiting concave ring 212. It should be noted that the outer limiting protrusion... The upper and lower sides of the connection between 214 and the outer wall of the docking sleeve 28 are provided with annular inner grooves. The inner limiting protrusion 211 is placed in the annular inner groove. Through the limiting connection of the inner limiting protrusion 211, the limiting concave ring 212 and the outer limiting protrusion 214, the inner limiting protrusion 211 on the docking outer tube 210 can be inserted into the annular inner groove, forming a groove-and-concave locking docking of the docking part, which constrains the docking sleeve 28 in the axial direction and prevents it from coming out of the docking outer tube 210.

[0043] Furthermore, the outer limiting protruding ring 214 has a locking block placement groove 216 on its ring body, and a spring 217 is placed in the locking block placement groove 216. The inner wall of the limiting concave ring 212 has a limiting groove 213. The upper end of the limiting locking block 215 is locked in the limiting groove 213, and the lower end of the limiting locking block 215 is locked in the locking block placement groove 216. The spring 217 abuts against the bottom end of the limiting locking block 215. When the docking sleeve 28 rotates relative to the docking outer tube 210, the top of the limiting locking block 215 will continuously slide into and out of the multiple limiting grooves 213 distributed in a ring on the inner wall of the limiting concave ring 212 under the action of the spring 217. Each time it slides into the groove, it will produce a clear "click" sound and a tactile tactile jolt, providing the operator with clear and intuitive feedback on whether it is screwed in place. This avoids the situation where the connection is not secure due to insufficient screwing, and also prevents the problem of inconvenient disassembly later due to excessive screwing.

[0044] Furthermore, one side of the inner wall of the limiting groove 213 is an outwardly inclined slope, and one side of the upper part of the limiting block 215 is also inclined. The inclined block of the upper part of the limiting block 215 is in close contact with the inclined inner wall of the limiting groove 213. During the installation process of tightening in the forward direction, the guiding effect of the slope allows the limiting block 215 to slide more smoothly over the edge of the limiting groove 213, compress the spring 217 and enter the next groove, thereby producing a clear sense of positioning and allowing continuous rotation until tightened. When disassembling by rotating in the reverse direction, the other side of the upper part of the limiting block 215... The surface will wedge tightly against the inner wall of the limiting groove 213, forming a self-locking effect. When the inner tube 26 is rotated in the opposite direction to remove the front protective head 22, the applied torque will be directly transmitted to the outer tube 210 through the locking action of the limiting block 215 in the limiting groove 213, thereby driving the entire connecting sleeve 28 and the outer tube 210 to rotate together without relative movement or unlocking. This ensures that during disassembly, the rotational force is directly used to loosen the threaded connection between the inner tube 26 and the connecting sleeve 28, thus smoothly achieving the disassembly of the front protective head 22.

[0045] Furthermore, the inner wall of the outer tube 210 is provided with an inner friction surface 218, and the outer wall of the sleeve 28 is provided with an outer friction surface 219. The static friction between the two friction surfaces is used to achieve a fixed connection in the initial state, ensuring that the sleeve 28 can be stably held in the outer tube 210 when it is not connected to the inner tube 26, so as to complete the threaded connection process. Secondly, when the inner tube 26 is screwed into the sleeve 28 and the torque finally applied is greater than the static friction, the sleeve 28 can start to rotate relative to the outer tube 210, thereby triggering the subsequent engagement process of the limiting block 215 and the limiting groove 213.

[0046] Working principle: The surgeon first selects the front protective head 22 of the retraction plate 23 with a specific outward tilt angle according to the needs of the operation. The angle can be 0°, 4° or 7.5°. During installation, the docking inner tube 26 at the upper end of the selected front protective head 22 is aligned and inserted into the docking outer tube 210 at the front end of the outer sleeve 2, so that the external thread ring 27 on the outer wall of the docking inner tube 26 and the internal thread ring 29 on the inner wall of the docking sleeve 28 begin to engage. The front protective head 22 is rotated so that the docking inner tube 26 and the docking sleeve 28 are gradually tightened through the threads. Initially, the docking sleeve 28 is kept fixed by the static friction between the external friction surface 219 on its outer wall and the internal friction surface 218 on the inner wall of the docking outer tube 210.

[0047] After the thread is tightened, the rotational force continues to be applied. This force overcomes the static friction force, causing the mating sleeve 28 to begin rotating relative to the mating outer tube 210. At this time, the limiting block 215, which is elastically set on the outer limiting protrusion ring 214, slides along the inclined inner wall of the limiting groove 213 on the inner wall of the limiting concave ring 212 under the action of the spring 217, and slides into the next limiting groove 213 in sequence. During this process, a "click" sound is emitted and a tactile tactile feedback is generated, providing the operator with clear feedback that the screw is tightened to the correct position, indicating that the installation is secure.

[0048] During operation, the assembled instruments are placed into the surgical area. The smooth rolled edge 25 at the front end of the retraction piece 23 of the outer tube 2 is used to gently retract and protect the nerve root or ligamentum flavum and other tissues to prevent them from being dislodged or damaged. The surgeon can observe the state of the retracted tissue in real time through the observation window 24 on the front protective head 22. The outer tube 2 can be held stably by the hand support plate 21.

[0049] When the front protective head 22 needs to be replaced, it can be disassembled by rotating it in the opposite direction. Since the limiting groove 213 and the inclined surface of the limiting block 215 are wedged together to form a self-locking mechanism, the reverse torque will be directly transmitted to the docking outer tube 210 through the limiting block 215, which will drive the docking sleeve 28 to rotate together, thereby smoothly loosening the threaded connection and completing the disassembly.

[0050] It will be apparent to those skilled in the art that this invention is not limited to the details of the exemplary embodiments described above, and that it can be implemented in other specific forms without departing from the spirit or essential characteristics of this invention. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of this invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within this invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0051] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A cannula nerve retractor for separating and exposing protected nerve tissue, comprising an outer cannula (2), characterized in that: The front end of the outer tube (2) is movably connected to a front protective head (22); The front protective head (22) is provided with an observation window (24). The front end of the inclined opening of the front protective head (22) is connected to a pull-out piece (23). There are multiple front protective heads (22), and each pull-out piece (23) connected to the front protective head (22) has a different outward tilt angle. The outer wall of the front end of the pull-out piece (23) is connected to a rolled edge (25). The outer tube (2) has a docking outer tube (210) at its front end. A docking sleeve (28) is connected to the inner end of the docking outer tube (210). The upper end of the front protective head (22) is connected to a docking inner tube (26). The docking inner tube (26) and the docking sleeve (28) are threadedly connected. Multiple sets of limiting ring units are provided between the docking outer tube (210) and the docking sleeve (28). Each set of limiting ring units is elastically provided with multiple limiting blocks (215). In the initial state, the docking sleeve (28) is fixedly connected to the docking outer tube (210) by friction. After the docking inner tube (26) and the docking sleeve (28) are threadedly tightened, the docking sleeve (28) can be rotatably connected relative to the docking outer tube (210).

2. The cannula nerve retractor for separating, exposing, and protecting nerve tissue according to claim 1, characterized in that: An endoscope (1) is movably inserted inside the outer tube (2), and a small gap fit is formed between the tube of the endoscope (1) and the inner wall of the outer tube (2).

3. The cannula nerve retractor for separating and exposing protected nerve tissue according to claim 1, characterized in that: The upper end of the outer tube (2) is connected to a handrail (21).

4. The cannula nerve retractor for separating and exposing protected nerve tissue according to claim 1, characterized in that: The outward tilt angle of the pull-out piece (23) connected to the front protective head (22) includes 0°, 4° or 7.5°.

5. The cannula nerve retractor for separating and exposing protected nerve tissue according to claim 1, characterized in that: The outer wall of the inner tube (26) is provided with an external thread ring (27), and the inner wall of the sleeve (28) is provided with an internal thread ring (29), and the external thread ring (27) and the internal thread ring (29) are threadedly connected.

6. The cannula nerve retractor for separating and exposing protected nerve tissue according to claim 1, characterized in that: The limiting ring unit includes an inner limiting protrusion (211), a limiting concave ring (212), and an outer limiting protrusion (214). The inner limiting protrusion (211) is connected to the inner wall of the docking outer tube (210). The limiting concave ring (212) is opened on the outer wall of the docking outer tube (210), and the inner limiting protrusion (211) is located on the upper and lower sides of the limiting concave ring (212). The outer limiting protrusion (214) is connected to the outer wall of the docking sleeve (28), and the outer limiting protrusion (214) is locked inside the limiting concave ring (212).

7. The cannula nerve retractor for separating and exposing protected nerve tissue according to claim 6, characterized in that: The outer limiting protruding ring (214) has a locking block placement groove (216) on its ring body. A spring (217) is placed in the locking block placement groove (216). The inner wall of the limiting concave ring (212) has a limiting groove (213). The upper end of the limiting locking block (215) is locked in the limiting groove (213), and the lower end of the limiting locking block (215) is locked in the locking block placement groove (216). The spring (217) abuts against the bottom end of the limiting locking block (215).

8. The cannula nerve retractor for separating and exposing protected nerve tissue according to claim 7, characterized in that: The inner wall of the limiting groove (213) is inclined outward, and one side of the upper block of the limiting block (215) is inclined, and the inclined block of the upper end of the limiting block (215) is closely attached to the inclined inner wall of the limiting groove (213).

9. The cannula nerve retractor for separating and exposing protected nerve tissue according to claim 1, characterized in that: The inner wall of the outer tube (210) is provided with an inner friction surface (218), and the outer wall of the sleeve (28) is provided with an outer friction surface (219).

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