Biomechanics HAND AND WRIST joint ..pptx

Biomechanics of wrist and hand

1. BIOMECHANICS OF WRIST AND HAND COMPLEX

2. The human hand may well surpass all body parts except the brain as a topic of universal interest. The human hand has been characterized as a symbol of power , as an extension of intellect, and as the seat of the will . The symbiotic relation of the mind and hand is exemplified by sociologists’ claim that the brain is responsible for the design of civilization but the hand is responsible for its formation. INTRO…

3. The hand cannot function without the brain to control it; likewise, the encapsulated brain needs the hand as a primary tool of expression . The entire upper limb is subservient to the hand . Any loss of function in the upper limb, regardless of the segment, ultimately translates into diminished function of its most distal joints.

4. The wrist consist of two compound joints; the radiocarpal and the midcarpal joints, collectively called as wrist complex. Functions: 1.Its serves to broaden the placement of hand in space and to increase the degree of freedom available to the hand. 2.The major role of wrist joint is the length –tension relationship adjustment of extrinsic muscle in the multi-articular joints of the hand. 3.so that its major function is balance and control rather than torque production . Wrist complex and function

5. Radiocarpal Joint Proximal row Radius Distal row Scaphoid Lunate Triquetrum Midcarpal Joint Proximal row Scaphoid Lunate Triquetrum Distal row trapezium Trapezoid Capitate Hamate Wrist Complex

6. Wrist Complex

7. Ligaments: 3 Volar carpal ligaments Radio scaphocapitate ( radio capitate ) lig . Short and long radio lunate Radio scapholunate lig . 2 Dorsal carpal ligaments Dorsal radio-carpal lig . Dorsal intercarpal lig . Ligaments

8. Muscles : 6 Volar wrist muscles: PL – PALMARIS LONGUS FCR – FLEXOR CARPI RADIALIS FCU – FLEXOR CARPI ULNARIS FDS – FLEXOR DIGITORUS SUPERFICIALIS FDP – FLEXOR DIGITORUM PROFUNDUS FPL – FLEXOR POLLICES LONGUS Dorsal wrist muscles: 3 primary volar wrist muscles: ECRL & ECRB ECU – EXTENSOR CARPI ULNARIS 6 other muscles EDC – EXTORUM DIGITORUM COMMUNIS EDM – EXTENSOR DIGITORUM MINIMI EPL & EPLB – EXTENSOR POLLICIS BREVIS APL – ABDUCTOR POLLICIS LONGUS

9. The compound proximal radiocarpal joint surface is oblique, angled slightly volarly and ulnarly .

10. SHAPE AND POSITON RADIOCARPAL JOINT. It involves the broad end of radius and the two carpals scaphoids and the lunate .This ellipsoid joint allows movement in two planes i.e .flexion and extension. The ulna makes no actual contact with the carpals and is separated by fibrocartilage known as TFCC . (TRIANGULAR FIBROCARTILAGE COMPLEX)

11. SHAPE AND POSITION MIDCARPAL AND INTERCARPAL JOINT Proximal rows are more mobile than distal row. Articulation between proximal and distal row of carpals

12. When the hand flexes at the wrist ,the movement begins at the midcarpal joint. The mid-carpal joint accounts for 60% of total range of motion of wrist & 40% of wrist flexion is attributable to movement of scaphoid and lunate on radius. Total ROM for wrist flexion is 65 to 85 DEGREE although 10-15 degree of wrist flexion is needed for most of the daily activities. ROM flexion

13. Wrist extension is also initiated at the midcarpal joint with more than 60% of movement now produced at radiocarpal joint and more than 30 % at midcarpal joint. The ROM for extension of wrist 60 to 85 DEGREE with approximate 35 degree of extension needed for daily activities. ROM extension

14. The hand can also move laterally in radial & ulnar flexion or deviation .In the radial flexion movement ,the proximal row moves towards the ulna and distal row moves towards radius. The opposite occurs 4 ulnar flexion. 15 to 21 degrees of radial deviation, and 20 to 45 degrees of ulnar deviation. The close packed position for the wrist in which maximal support is offered is in hyperextended position.The close packed position for midcarpal joint is radial flexion. ROM radio-ulnar deviation

15. Introduction : It consist of five digits- four finger and a thumb Each digit has a CMC joint and MP joint Each of four fingers have PIP & DIP Joints,while thumb has only one DIP JOINT TOTAL 19 BONES AND 19 JOINTS makes the hand complex distal to wrist joint. The hand complex

16. Carpometacarpal joints This joint connects the carpal with each of the five fingers via the metacarpals.The CMC articulation is a joint which provide most of the thumb movement and least of the finger movement. For the four fingers the joint is gliding type that moves directionally with the carpals. The movement is very restricted at the 2 nd and 3 rd cmc but increases to allow as much as ring and little finger. Anatomy

17. The CMC joint of the first ray ,or thumb is a saddle joint consisting of the articulation between trapezium and the first metacarpal.It provides the thumb with the most of its Rom allowing for 50 to 80 degree of flexion and extension,40-80 degree of abduction and adduction and 10-15 of rotation. The thumb can touch each of the finger in the movement of opposition & is very imp in all gripping & prehension tasks. ROM

18. Metacarpophalangeal joint- The metacarpal connect with the phalanges to form the MCP joints.The function of the MCP joints of the four fingers differs from that of the thumb. The MCP joint of the four fingers are condyloid joint allowing movements in two planes.( i ) F/E (ii) AB/Ad Anatomy

19. The finger can flex through 70-90 degree with most flexion in little finger and least in the index finger. Flexion which determines grip strength , can be more effective and produces more force when the wrist joint held in 20 -30 degree of hyperextension ,the position that increases length of finger flexors. Extension of the finger at the MCP joint can take place through about 25 degree of motion. The extension is limited by the position of the wrist. That is finger extension can be limited with wrist hyper extended and vice versa. ROM

20. The MCP for the thumb is a hinge joint allowing motion in one plane. 30-90- degree of flexion and 15 degree of extension can take place at this joint. ROM OF THUMB

21. INTERPHALANGEAL JOINT The most distal joints in the upper extremity link are the IP articulation .Each finger has 2 IP joints.,Proximal & Distal. The thumb has only one IP joint & consequently has two phalanges. The IP joint are hinge joint allowing for movement in one plane only (F/E).& they are reinfoeced on the lateral sides of the joint by collateral ligamens that restrict movement oher than flexion & extension. ANATOMY

22. Flexion for PIP- 110 degree DIP- 90 degree As with the MCP joint ,the flexion strength at these joint determines grip strength .It can be enhanced with wrist hyperextended by 20 degree and is impaired if the wrist is flexed. There is usually no hyperextension allowed at the IP joint unless an individual has long ligaments that allow extension because of joint laxity. ROM

23. palmar arch The palmar arch system assists with functional grasp . The proximal transverse arch (A) is fixed, while the distal transverse arch (B) and longitudinal arch (C) are mobile.