Anatomy of the wrist joint and hand

The wrist joint is formed by the articular surface of the radius and the distal surface of the articular disc, represented by the scaphoid, lunate and triquetral bones.

The stability of the joint is ensured by two lateral ligaments of the wrist: the radial ligament, attached to the styloid process of the radius and the scaphoid bone, and the ulnar ligament, which starts from the styloid process of the ulna and attaches to the triquetral bone and partially to the pisiform bone. On the dorsal and palmar sides, the wrist joint is strengthened by the dorsal palmar and radiocarpal ligaments. Flexion, extension, adduction, abduction and rotation are performed in the wrist joint. The interphalangeal joints of the hand are located between the adjacent phalanges of each finger. The ligamentous apparatus of the interphalangeal joints of the hand is represented by the palmar ligaments, which extend from the lateral surfaces of the blocks and are attached: some - to the lateral surface of the phalanges - lateral ligaments, and others - to their palmar surface. The first thumb has one interphalangeal joint. The tendons of the superficial and deep flexors of the fingers pass along the palmar surface of the hand.

On the back of the wrist there is a wide strengthening fibrous band - extensor retinaculum, which consists of several ligaments that form 6 pockets or sections, each of which has a synovial sheath for the tendons of the extensors of the hand passing there. In the first pocket, located near the styloid process of the radius, lie the fibers of the tendon that abducts the finger and the short extensor of the fingers. The tendons of the long and short radial extensors of the carpus lie in the second pocket, lateral to the dorsal tubercle of the radius. In the third pocket, medial to the dorsal tubercle, is located the tendon of the long extensor of the fingers. In the fourth pocket lie the tendons of the extensors of the fingers and the extensor of the index finger. In the fifth pocket - the tendon of the extensor of the little finger. In the sixth pocket - the elbow extensor of the wrist. On the inner or palmar side of the wrist there is also a strengthening fibrous strand of only the tendons of the flexors of the hand - flexor retinaculum, forming the carpal tunnel.

This fibrous band is attached medially to the pisiform bone and laterally to the hamate bone, where it divides into 2 layers that attach to the tubercles of the scaphoid and trapezoid bones. The tendon of the radial flexor carpi radialis is located between the two layers of the fibrous band, where the tendons of the deep and superficial flexors of the fingers, the tendon of the long flexor of the fingers and the medial nerve pass. The tendon of the long flexor of the fingers is located closer to the radial surface of the canal and has its own synovial sheath. The other 8 flexor tendons are enclosed in a common tendon sheath. On the hand, the tendons of the superficial flexors of the fingers attach to the proximal part of the middle phalanx of the fingers. The tendons of the deep flexors of the fingers attach to the base of the distal phalanx. The flexor tendons of the fingers are fixed to the phalanges by the anular ligaments.

Median nerve.

The medial nerve is formed from the C6-T1 roots with possible involvement of C5. It runs in the neuromuscular bundle on the shoulder with the brachial artery and ulnar nerve. In the distal part of the shoulder, it runs in the aponeurosis of the biceps muscle between the two heads of the pronator teres.

On the forearm, it is located between the superficial and deep flexors of the fingers. Ascending upward, the medial nerve enters the carpal tunnel. It innervates the pronator teres, flexor digitorum radialis, long palmar, superficial flexor digitorum, lateral part of the deep flexor digitorum, long flexor pollicis, square pronator, thenar muscles, lumbrical muscles of the 1st and 2nd phalanges of the fingers; and also provides sensitivity to the 1st, 2nd, 3rd fingers and half of the 4th finger from the palmar surface.

The nerve passes through the carpal tunnel lateral and superior to the flexor tendons of the fingers. In the tunnel it lies between the flexor carpi radialis and the flexor digitorum superficialis deep to the long palmar tendon. The flexor carpi ulnaris tendon is located medially at the ulna and is enclosed in a synovial sheath.

Between the tendons of the flexor digitorum and the tendon of the flexor carpi ulnaris are the ulnar artery and nerve. The ulnar nerve is lateral to the pisiform bone but medial to the hook of the hamate bone. Here the ulnar artery lies anterior and lateral to the nerve.

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