A curved structure, an insertion portion, and a medical catheter

Abstract

The application provides a bending structure, an insertion part and a medical catheter, and relates to the technical field of medical devices. The bending structure comprises a flexible bending tube and at least two traction flat wires. The flexible bending tube has a device channel for a device tube to pass through. The flexible bending tube comprises at least two bending sections which are connected in sequence along the axial direction of the flexible bending tube. The traction flat wires of the embodiment of the application have different bending rigidities in different directions. After being stressed, the traction flat wires preferentially bend along the width direction or the thickness direction of the traction flat wires. Even if the traction flat wires are applied to the flexible bending tube of universal bending, the traction flat wires can realize the constraint on the bending direction by relying on the cross-sectional characteristics of the traction flat wires, so that the flexible bending tube can accurately bend towards the specified direction, and the flexible bending tube can be prevented from being greatly twisted in an unintended manner. The traction flat wires have more excellent bending control performance, and the control precision of multi-section bending of the insertion part can be improved.

Description

Technical Field

[0001] This application relates to the field of medical device technology, and in particular to a curved structure, an insertion part, and a medical catheter. Background Technology

[0002] In clinical practice, catheter-based instruments are commonly used to intervene in human cavities during intracavitary diagnostic and treatment procedures. The insertion end of an endoscope is a typical flexible catheter component, and specialized catheters can also be directly inserted to deliver biopsy forceps, laser fibers, sampling instruments, and other diagnostic and treatment accessories into the body. Since most human cavities have circuitous paths, narrow inner diameters, and complex bends, clinical practice requires the use of a traction component at the rear end of the catheter to adjust the posture of the bend at the front end, adapting to the cavity's direction for flexible steering and precise arrival at the lesion area.

[0003] The flexible catheter adopts a universal bending structure, which cannot limit the fixed bending direction. If the bending direction of the flexible catheter does not meet the expected requirements, it will seriously affect the smoothness of the endoscope's turning and control and the positioning accuracy. Summary of the Invention

[0004] The purpose of this application is to provide a curved structure, an insertion part, and a medical catheter to alleviate or solve the aforementioned technical problems existing in the prior art.

[0005] In a first aspect, embodiments of this application provide a bending structure for a medical catheter. The bending structure includes a flexible bending tube and at least two traction flat wires. The flexible bending tube has an instrument channel for inserting an instrument tube. The flexible bending tube includes at least two bending segments connected sequentially along the axial direction of the flexible bending tube. The traction flat wires extend along the axial direction of the flexible bending tube. Each bending segment is provided with at least one traction flat wire. One end of the traction flat wire is fixedly connected to the distal end of the corresponding bending segment, and the other end extends to the proximal end of the flexible bending tube. The traction flat wire is used to drive the corresponding bending segment to bend and deform.

[0006] Secondly, embodiments of this application also provide an insertion portion, including the curved structure described in the first aspect.

[0007] Thirdly, embodiments of this application also provide a medical catheter, including a handle and an insertion portion as described in the second aspect, disposed at the distal end of the handle.

[0008] The technical solution adopted in this application embodiment can achieve the following beneficial effects: The flexible bending tube is composed of multiple bending segments connected sequentially along the axial direction, and each bending segment is independently equipped with a traction flat wire extending along the axial direction. The traction flat wires are all arranged to extend along the axial direction of the flexible bending tube. One end of the traction flat wire is fixedly connected to the distal end of the corresponding bending segment, and the other end extends to the proximal end of the flexible bending tube. Medical personnel can pull the proximal end of the traction flat wire to drive the bending deformation of the corresponding bending segment, so as to achieve bending control of different bending segments.

[0009] Compared to existing technologies, the traction flat wire in this embodiment exhibits varying bending stiffness in different directions. Under stress, it preferentially bends along its width or thickness. Even when applied to a flexible bending tube with omnidirectional bending, the traction flat wire can constrain the bending direction based on its cross-sectional characteristics, ensuring the flexible bending tube bends accurately in the specified direction and preventing large-scale unintended bending or torsion. Compared to round wire drive solutions, the traction flat wire offers superior bending control performance, improving the control accuracy of multi-segment bending in the insertion section and effectively preventing the bending directions of multiple bending segments from deviating from the preset trajectory. Attached Figure Description

[0010] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0011] Figure 1 This is a schematic diagram of the structure of a medical catheter shown in an exemplary embodiment of this application; Figure 2 This is a schematic diagram of the structure of the flat wire and instrument tube shown in an exemplary embodiment of this application; Figure 3 This is a schematic diagram of the structure of the insertion part shown in an exemplary embodiment of this application; Figure 4 yes Figure 3 A sectional view along AA in the diagram; Figure 5 yes Figure 3 A sectional view along BB in the middle; Figure 6 This is a schematic diagram of the insertion part from another perspective, illustrating an exemplary embodiment of this application; Figure 7 This is an exploded view of the connecting flange, socket, and front end seat, illustrating an exemplary embodiment of this application; Figure 8 This is a cross-sectional view of the connecting flange, socket, and front end seat, illustrating an exemplary embodiment of this application.

[0012] In the diagram: 1. Insertion section; 100. Bending structure; 110. Flexible bending tube; 111. Bending section; 111a. First bending section; 111b. Second bending section; 112. Connecting flange; 1121. Conducting channel; 1122. Traction channel; 120. Traction flat wire; 120a. First traction flat wire; 120b. Second traction flat wire; 130. Passive bending section; 200. Front end seat; 210. Guide surface; 300. Socket; 400. Instrument tube; 500. Handle; 2. Medical catheter. Detailed Implementation

[0013] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be described in detail below. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. Based on the embodiments in this application, all other implementation methods obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0014] The terms "first," "second," etc., used in the specification and claims of this application are used to distinguish similar objects and not to describe a specific order or sequence. It should be understood that such use of data can be interchanged where appropriate so that embodiments of this application can be implemented in orders other than those illustrated or described herein, and the objects distinguished by "first," "second," etc., are generally of the same class and the number of objects is not limited; for example, a first object can be one or more. Furthermore, in the specification and claims, "and / or" indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0015] In the prior art, the applicant discovered during the development of this application that flexible conduits employ a universal bending structure, which is prone to bending under stress, resulting in poor controllability of the bending direction. Compared to existing serpentine bending segment structures, this type of flexible conduit cannot constrain the bending direction. To adapt to the bending path requirements under complex working conditions, the flexible conduit adopts a segmented bending structure, meaning that multiple bending segments on the flexible conduit bend independently. With a segmented bending structure, under the tension of the traction structure, each bending segment is highly susceptible to deviating from the preset bending trajectory. The directional deviations generated by multiple segments accumulate and superimpose, ultimately causing unexpected torsional deformation of the entire flexible conduit.

[0016] This application provides a bending structure 100, please refer to... Figure 1This is used for medical catheter 2. It should be noted that the medical catheter 2 in this embodiment can be a standalone catheter structure or insertion part 1, or it can be integrated into medical devices such as endoscopes or interventional devices. In the medical industry, endoscopes, catheters (insertion part 1), etc., essentially all fall under the category of medical catheter 2. For specific implementation details, please refer to... Figure 2 and Figure 3 The bending structure 100 includes a flexible bending tube 110 and at least two traction flat wires 120, which work together to achieve bending control. The number of traction flat wires 120 can be two, three or more, and is not limited.

[0017] Understandably, for the flexible bending pipe 110, a passive bending section 130 is generally installed near its proximal end. The passive bending section 130 is sequentially connected to the flexible bending pipe 110 along the axial direction to increase the overall effective length of the bending structure 100 and to buffer and transition the stress on the flexible bending pipe 110 during operation. The passive bending section 130 is generally also composed of a pipe structure, and its outer diameter is consistent with that of the flexible bending pipe 110 or gradually varied as needed.

[0018] Please see Figure 3 The flexible bending tube 110 can be made of medical flexible materials such as polyurethane or silicone rubber, which can bend under external traction. The flexible bending tube 110 has an instrument channel for the instrument tube 400 to pass through. For example, the flexible bending tube 110 can be manufactured using a one-piece injection molding process, with the instrument channel formed simultaneously during injection molding. The shape and specifications of the instrument channel can be adapted to the instrument tube 400. For example, the cross-section of the instrument channel can be circular, and the instrument tube 400 can be a cylindrical structure, so that the instrument tube 400 can be smoothly installed inside the instrument channel.

[0019] Please see Figure 3 The flexible curved pipe 110 includes at least two curved segments 111. The number of curved segments 111 can be two, three, or more, and is not limited. The at least two curved segments 111 are connected sequentially along the axial direction of the flexible curved pipe 110. For example, the curved segments 111 are different pipe segments divided along the length direction of the flexible curved pipe 110. The lengths between the at least two curved segments 111 can be equal or different, and this application does not limit this.

[0020] Please see Figure 2The traction flat wires 120 extend axially along the flexible bending tube 110. Each bending segment 111 has at least one traction flat wire 120. One end of the traction flat wire 120 is fixedly connected to the distal end of the corresponding bending segment 111, and the other end extends to the proximal end of the flexible bending tube 110. The traction flat wires 120 are used to drive the bending deformation of the corresponding bending segment 111. The traction flat wires 120 extend axially along the flexible bending tube 110. Further, the flexible bending tube 110 has a rectangular through-channel in its wall. The extension direction of the through-channel is parallel or collinear with the central axis of the flexible bending tube 110. The traction flat wires 120 pass through the through-channel. At the distal end of the corresponding bending segment 111, the end of the traction flat wire 120 is connected and fixed to the wall of the through-channel. Medical staff can pull the proximal end of the traction flat wire 120 to drive the corresponding bending segment 111 to bend and deform, so as to achieve bending control of different bending segments 111.

[0021] Compared to existing technologies, please refer to Figure 4 In this embodiment, the traction flat wire 120 exhibits varying bending stiffness in different directions. Under stress, it preferentially bends along its width or thickness direction. Even when applied to a omnidirectional flexible bending tube 110, the traction flat wire 120 can constrain the bending direction based on its cross-sectional characteristics, ensuring the flexible bending tube 110 bends accurately in the specified direction and preventing significant unintended torsion. Compared to a round wire drive scheme, the traction flat wire 120 offers superior bending control performance, improving the control accuracy of multi-segment bending in the insertion section 1 and effectively preventing deviations in the bending direction between bending segments 111 from the preset trajectory.

[0022] Understandably, Figure 4 Establish a rectangular coordinate system, with the width direction of the 120mm traction flat wire as follows: Figure 4 In the x-direction, the thickness direction of the traction flat wire 120 is... Figure 4 The y-direction. See also Figure 4 When the traction flat wire 120 is subjected to a pulling force, it will preferentially bend along its own width or thickness direction. This is because the bending stiffness of the traction flat wire 120 is smaller in the width or thickness direction, and the external force will always preferentially force the traction flat wire 120 to bend along the direction with smaller bending stiffness, rather than preferentially bending along the diagonal (edge ​​direction). When medical staff pull the proximal end of the traction flat wire 120, it can cause the flexible bending tube 110 to bend approximately to the corresponding side. In addition, relying on the directional bending effect of the traction flat wire 120 itself, the flexible bending tube 110 is bent in the accurate direction (i.e., the width or thickness direction of the corresponding traction flat wire 120), which can further improve the bending accuracy of the flexible bending tube 110.

[0023] In the embodiments of this application, please refer to Figure 2 and Figure 4 The traction flat wire 120 is rectangular in shape, with at least one face perpendicular to the radial direction of the flexible bending tube 110. In other words, the width or thickness direction of the traction flat wire 120 coincides with or is parallel to the radial direction of the flexible bending tube 110. Furthermore, the flat wire is easier to bend along its width or thickness direction, and this bending direction remains approximately the same as the radial direction of the flexible bending tube 110. This arrangement can suppress or eliminate the tendency of the traction flat wire 120 to circumferentially roll or laterally deviate. Under the action of traction force, the force applied by the traction flat wire 120 to the flexible bending tube 110 is transmitted radially, reducing unexpected offset moments and ensuring that the bending force direction always remains consistent with the preset direction. This stabilizes and constrains the deformation posture of the flexible bending tube 110, ensuring the directional bending effect of the medical catheter 2. In addition, existing round wires only have line contact with the tube wall, while the traction flat wire 120 of this application embodiment can rely on its flat surface to fit tightly against the inner wall of the flexible curved tube 110, forming a surface-to-surface contact at the connection position, resulting in a larger force contact area and effectively improving the force application stability during the traction process.

[0024] For further details, please refer to Figure 4 and Figure 5 The traction flat wire 120 includes multiple sub-flat wires, the number of which can be two, three, or more, without limitation. These multiple sub-flat wires are arranged at intervals along the circumference of the flexible bending tube 110 and connected to the distal end of the bending section 111 to control the bending of the corresponding bending section 111 along different radial directions. For example, within a bending section 111 of the flexible bending tube 110, the traction flat wire 120 includes a first sub-flat wire and a second sub-flat wire, which are respectively arranged at opposite ends of the same diameter. Medical personnel can drive the bending section 111 to bend to the left or right by pulling the first or second sub-flat wire. Of course, in other cases, the bending section 111 can also be equipped with a greater number of sub-flat wires to achieve multi-directional bending of the bending section 111. This setup utilizes multiple sub-flat wires arranged at circumferential intervals, with each sub-flat wire corresponding to a different radial orientation of the bending section 111. When a traction force is applied to the sub-flat wires at different circumferential positions, an independent bending moment can be formed at different radial positions of the bending section 111, driving the bending section 111 to deform toward the corresponding force orientation. This enables the flexible bending tube 110 to have multi-radial bending adjustment capabilities, effectively improving the scenario adaptability of the medical catheter 2.

[0025] In the embodiments of this application, please refer to Figure 5In this design, sub-flat wires 120 with the same bending direction are arranged radially along the flexible bending tube 110, and the thickness direction of the sub-flat wires coincides with the arrangement direction of the multiple traction flat wires 120. In other words, the traction flat wires 120 used for bending in the same direction within different bending sections 111 are arranged radially. This application uses the thickness direction of the sub-flat wires as the radial stacking direction. Taking advantage of the structural advantage that the thickness of the flat wires is much smaller than the diameter of traditional round wires, the overall thickness of multiple sets of sub-flat wires stacked radially in the same direction can be significantly reduced while ensuring that the cross-sectional area of ​​the traction flat wires 120 is the same. This layout reduces the volume occupied by the traction structure in the radial direction of the flexible bending tube 110 from a spatial perspective. Multiple sets of radially arranged traction structures can be arranged without increasing the outer diameter of the catheter, without occupying the assembly space of the instrument tube 400 or the internal channel space of the catheter, effectively solving the problem of the traction structure causing the outer diameter of the catheter to be too large and the internal structure to interfere.

[0026] For example, please see Figure 3 The flexible bending tube 110 may include a first bending segment 111a and a second bending segment 111b, with the proximal end of the first bending segment 111a connected to the second bending segment 111b. The lengths of the first bending segment 111a and the second bending segment 111b may be the same or different, and their outer diameters may be the same or gradually varied as needed. The traction flat wire 120 includes a first traction flat wire 120a and a second traction flat wire 120b. The first traction flat wire 120a passes through the second bending segment 111b and connects to the distal end of the first bending segment 111a, while the second traction flat wire 120b connects to the distal end of the second bending segment 111b. This arrangement allows the first traction flat wire 120a to exert a traction force only on the first bending segment 111a without affecting the stress on the second bending segment 111b, and the second traction flat wire 120b to independently engage with the second bending segment 111b, forming an independently bent bending segment 111. It should be noted that the second bending segment 111b is also equipped with a sheath, which connects to the distal end of the second bending segment 111b. The sheath can be fitted with the first traction flat wire 120a to prevent the first traction flat wire 120a from being driven by force on the second bending segment 111b. This arrangement allows for individual bending control of the first bending segment 111a and the second bending segment 111b, completing the segmented bending function, enriching the bending posture of the medical catheter 2, and improving the catheter's passage performance in complex tortuous cavities within the body.

[0027] In one implementation, please refer to Figure 5The radius of the flexible bending tube 110 is 8 to 10 times the thickness of the traction flat wire 120, such as 8, 9, or 10 times. The radius of the flexible bending tube 110 should not be too large or too small relative to the thickness of the traction flat wire 120. If the ratio is larger than this range, the thickness of the traction flat wire 120 is relatively too small, resulting in insufficient structural load-bearing capacity and the inability of the traction force to effectively drive the flexible bending tube 110 to bend and deform. If the ratio is smaller than this range, the thickness of the traction flat wire 120 is relatively too large, which will encroach on the flexible deformation space of the tube wall, limiting the bending recovery ability of the bending section 111, and increasing the overall outer diameter of the medical catheter 2. This design ensures that the traction flat wire 120 has an appropriate thickness, balancing the driving strength of the traction flat wire 120 with the deformation recovery ability of the flexible bending tube 110, ensuring that the bending action of the medical catheter 2 is sensitive and the structure is stable.

[0028] In another implementation, please refer to Figure 5 The width of the traction flat wire 120 is 3 to 5 times its thickness, such as 3, 4, or 5 times, and there is no restriction. The width-to-thickness ratio of the traction flat wire 120 limits its cross-sectional structure; the ratio should not be too large or too small. If the ratio is too large, the traction flat wire 120 is too thin and lacks rigidity, making it prone to bending and deformation under traction force, thus failing to effectively transmit the traction force. If the ratio is too small, the cross-section of the traction flat wire 120 approaches a square structure, losing its torsional resistance and directional force transmission characteristics, and is prone to bending or shifting to either side. A suitable width-to-thickness ratio allows the traction flat wire 120 to combine the advantages of structural rigidity and a flat, directional structure, enabling stable and precise transmission of traction force and ensuring precise and controllable bending movements of the medical catheter 2.

[0029] In the embodiments of this application, please refer to Figure 2 The flexible bending pipe 110 also includes a connecting flange 112, which is disposed at the end of the bending segment 111 and connects two adjacent bending segments 111. The connecting flange 112 can be a block structure or a ring structure, etc. Taking a block structure as an example, the connecting flange 112 can be bonded between two adjacent bending segments 111. Alternatively, in other cases, the connecting flange 112 can be a ring structure, with a spacer plate disposed inside the connecting flange 112. The connecting flange 112 can be fitted onto the adjacent end faces of two adjacent bending segments 111, while the spacer plate is bonded to the adjacent end faces of two adjacent bending segments 111. The connecting flange 112 can achieve axial docking and positioning of two bending segments 111, restricting misalignment and loosening of the segmented structure and improving connection stability.

[0030] Please see Figure 5The connecting flange 112 has a through-channel 1121 and a traction channel 1122, with the traction channel 1122 arranged around the through-channel 1121. The instrument tube 400 passes through and is fixed within the through-channel 1121, while the traction flat wire 120 passes through the traction channel 1122. This arrangement separates the instrument tube 400 from the traction flat wire 120, spatially isolating them from movement interference. This ensures the overall assembly stability of the segmented flexible bending tube 110, as well as the secure fixing of the instrument tube 400 and the smooth sliding of the traction flat wire 120.

[0031] This application embodiment also provides an insertion part 1, please refer to... Figure 3 and Figure 6 The insertion part 1 includes the aforementioned curved structure 100.

[0032] In one implementation, please refer to Figure 7 and Figure 8 The insertion part 1 also includes a front end seat 200 and a socket 300. The socket 300 is connected to the distal end of the curved structure 100. For example, the socket 300 can be shaped like a hollow tube, capable of fitting onto the distal end of the curved structure 100. A guide surface 210 is provided on the proximal outer surface of the front end seat 200, and the guide surface 210 is radially inclined outward along the direction from the proximal end to the distal end of the front end seat 200. The proximal end of the front end seat 200 is embedded in the socket 300, and the guide surface 210 abuts against the inner wall of the socket 300. In other words, the guide surface 210 can be an annular inclined surface, capable of embedding into the socket 300 and pressing against the inner wall of the socket 300. During this process, the inclined guide surface 210 can play a radial guiding role in the process of the front end seat 200 being embedded into the socket 300, guiding the front end seat 200 to slide smoothly into the interior of the socket 300. After the guide surface 210 abuts against the inner wall of the socket 300, a radial limiting fit can be formed. The pre-positioning between the front seat 200 and the socket 300 is achieved by relying on the friction generated by the contact of their conical surfaces. During assembly, no additional tooling is required to keep the relative positions of the two from shifting, preventing the parts from becoming loose or misaligned before the bonding process, providing a stable assembly foundation for subsequent bonding operations, and improving bonding accuracy and assembly efficiency.

[0033] This application also provides a medical catheter 2, please refer to... Figure 1 The medical catheter 2 includes a handle 500 and the aforementioned insertion part 1, with the insertion part 1 located at the distal end of the handle 500.

[0034] In the field of medical devices, endoscopes are often referred to as medical catheters 2, and their structure also includes an insertion part 1 and a handle 500 for operation. Therefore, the technical solution of the aforementioned medical catheter 2 is also applicable to endoscopes and other related medical devices. By applying the bending structure 100 described in this application to the entire medical catheter 2, not only can the control precision and bending controllability of the catheter tip be improved, but it also helps to simplify the overall structural design, reduce assembly difficulty, and improve assembly consistency and clinical reliability. Of course, in other embodiments, the medical catheter 2 may not include the handle 500, and the technical solution of this application is still applicable.

[0035] It should be noted that the endoscopes referred to in the embodiments of this application may be bronchoscopes, pyeloscopes, esophagoscopes, gastroscopes, colonoscopes, otoscopes, rhinoscopes, oral endoscopes, laryngoscopes, colposcopes, laparoscopes, arthroscopes, etc. The embodiments of this application do not specifically limit the types of endoscopes.

[0036] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0037] Furthermore, it should be noted that the scope of the methods and apparatus in the embodiments of this application is not limited to performing functions in the order shown or discussed, but may also include performing functions substantially simultaneously or in the reverse order, depending on the functions involved. For example, the described methods may be performed in a different order than described, and various steps may be added, omitted, or combined. In addition, features described with reference to certain examples may be combined in other examples.

[0038] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application.

Claims

1. A curved structure for use in medical catheters, characterized in that, The bending structure includes a flexible bending tube (110) and at least two traction flat wires (120), wherein: The flexible curved tube (110) has an instrument channel for the instrument tube (400) to pass through. The flexible curved tube (110) includes at least two curved sections (111), and the at least two curved sections (111) are connected sequentially along the axial direction of the flexible curved tube (110). The traction flat wires (120) are all arranged to extend along the axial direction of the flexible bending tube (110). Each bending segment (111) is provided with at least one traction flat wire (120). One end of the traction flat wire (120) is fixedly connected to the far end of the corresponding bending segment (111), and the other end extends to the proximal end of the flexible bending tube (110). The traction flat wire (120) is used to drive the corresponding bending segment (111) to bend and deform.

2. The bending structure according to claim 1, characterized in that, At least one face of the traction flat wire (120) is radially perpendicular to the flexible curved tube (110).

3. The bending structure according to claim 2, characterized in that, The traction flat wire (120) includes a plurality of sub-flat wires, which are arranged at circumferential intervals along the flexible bending tube (110) and connected to the far end of the bending section (111) to control the bending of the corresponding bending section (111) along different radial directions.

4. The bending structure according to claim 3, characterized in that, In the plurality of traction flat wires (120), the sub-flat wires with the same bending direction are arranged along the same radial direction of the flexible bending tube (110), and the thickness direction of the sub-flat wires coincides with the arrangement direction among the plurality of traction flat wires (120).

5. The bending structure according to claim 3, characterized in that, The flexible curved tube (110) includes a first curved section (111a) and a second curved section (111b), the proximal end of the first curved section (111a) is connected to the second curved section (111b), the traction flat wire (120) includes a first traction flat wire (120a) and a second traction flat wire (120b), the first traction flat wire (120a) passes through the second curved section (111b) and is connected to the distal end of the first curved section (111a), and the second traction flat wire (120b) is connected to the distal end of the second curved section (111b).

6. The bending structure according to claim 2, characterized in that, The radius of the flexible curved tube (110) is 8 to 10 times the thickness of the traction flat wire (120); And / or, the width of the traction flat wire (120) is 3 to 5 times its thickness.

7. The bending structure according to claim 1, characterized in that, The flexible bending tube (110) also includes a connecting flange (112), which is located at the end of the bending section (111) and connected between two adjacent bending sections (111). The connecting flange (112) has a through-channel (1121) and a traction channel (1122) that pass through it. The traction channel (1122) is arranged around the through-channel (1121). The instrument tube (400) passes through and is fixed in the through-channel (1121). The traction flat wire (120) passes through the traction channel (1122).

8. An insertion part, characterized in that, Includes the bending structure as described in any one of claims 1-7.

9. The insertion portion according to claim 8, characterized in that, The insertion part further includes a front end seat (200) and a socket (300). The socket (300) is connected to the distal end of the curved structure. The proximal outer surface of the front end seat (200) is provided with a guide surface (210). Along the proximal to distal direction of the front end seat (200), the guide surface (210) is inclined outward along the radial direction of the front end seat (200). The proximal end of the front end seat (200) is embedded in the socket (300), and the guide surface (210) abuts against the inner wall of the socket (300).

10. A medical catheter, characterized in that, Includes a handle (500) and an insertion portion as described in claim 8 or 9 disposed at the distal end of the handle (500).

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