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Wrist

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The wrist is defined as the carpus or carpal bones, the complex of eight bones forming the proximal skeletal segment of the hand.

The wrist joint or radiocarpal joint, is the joint between the radius and the carpus and the region surrounding the carpus including the distal parts of the bones of the forearm and the proximal parts of the metacarpus or five metacarpal bones and the series of joints between these bones, thus ref2242ed to as wrist joints.

The wrist region also includes the carpal tunnel, the anatomical snuff box, bracelet lines, the flexor retinaculum, and the extensor retinaculum.

Armillas of the wrist, also known as rascette lines, vary in number from one to four.

The distal radioulnar joint is a pivot joint.

The distal radioulnar joint is located between the bones of the forearm, the radius and ulna.

The distal radioulnar joint is formed by the head of the ulna and the ulnar notch of the radius,

This joint is separated from the radiocarpal joint by an articular disk lying between the radius and the styloid process of the ulna.

With the proximal radioulnar joint, the distal radioulnar joint permits pronation and supination.

The radiocarpal joint or wrist joint is an ellipsoid joint formed by the radius and the articular disc proximally and the proximal row of carpal bones distally.

The carpal bones on the ulnar side only make intermittent contact with the proximal side.

The triquetrum bone only makes contact during ulnar abduction.

The capsule is continuous with the midcarpal joint and strengthened by numerous ligaments, including the palmar and dorsal radiocarpal ligaments, and the ulnar and radial collateral ligaments.

The parts forming the radiocarpal joint are the lower end of the radius and under surface of the articular disk above, and the scaphoid, lunate, and triquetral bones below.

The articular surface of the radius and the under surface of the articular disk form a the receiving cavity.

The superior articular surfaces of the scaphoid, lunate, and triquetrum form a smooth convex surface, the condyle, which is received into the concavity.

Carpal bones of the hand:

Proximal carpal bones of the hand Scaphoid, Lunate, Triquetrum, Pisiform

Distal carpal bones Trapezium, Trapezoid, Capitate, Hamate

In the hand a total of 13 bones form part of the wrist: eight carpal bones―scaphoid, lunate, triquetral, pisiform, trapezium, trapezoid, capitate, and hamate― and five metacarpal bones―the first, second, third, fourth, and fifth metacarpal bones.

The midcarpal joint is the joint space separating the proximal and distal rows of carpal bones.

The intercarpal joints, between the bones of each row, are strengthened by the radiate carpal and pisohamate ligaments and the palmar, interosseous, and dorsal intercarpal ligaments.

Some degree of mobility exists between the bones of the proximal row of carpal bones.

The bones of the distal row are connected to each other and to the metacarpal bones at the carpometacarpal joints by ligaments.

The joints between the bases of the metacarpal bones, the intermetacarpal articulations, are strengthened by dorsal, interosseous, and palmar intermetacarpal ligaments.

There is inter communication of the radiocarpal, intercarpal, midcarpal, carpometacarpal, and intermetacarpal joints via a common synovial cavity

The wrist has a proximal and distal articular surface.

The proximal articular surface is made up of the distal radius and the articular disc of the inferior radio-ulnar joint.

The distal articular surface is made up of proximal surfaces of the scaphoid, triquetral and lunate bones.

The extrinsic hand muscles are located in the forearm.

Most of the tendons of these muscles pass under the flexor retinaculum on the palmar side and the extensor retinaculum on the dorsal side.

On the palmar side the carpal bones form the carpal tunnel through which some of the flexor tendons pass in tendon sheaths.

The tendons slide back and forth through the narrow passageway.

Marginal movements of radial deviation include abduction as movement towards the thumb, and ulnar deviation with adduction, as movement towards the little finger.

Marginal movements take place about a dorsopalmar axis at the radiocarpal and midcarpal joints passing through the capitate bone.

The extensor carpi radialis longus, abductor pollicis longus, extensor pollicis longus, flexor carpi radialis, flexor pollicis longus muscles are involved with radial abduction.

Ulnar adduction involves the extensor carpi ulnaris, flexor carpi ulnaris, extensor digitorum, extensor digiti minimi muscles.

Extension involves extensor digitorum, extensor carpi radialis longus, extensor carpi radialis brevis, extensor indicis, extensor pollicis longus, extensor digiti minimi, extensor carpi ulnaris

Palmar flexion involves flexor digitorum superficialis, flexor digitorum profundus, flexor carpi ulnaris, flexor pollicis longus, flexor carpi radialis, abductor pollicis longus

Movements in the distal radioulnar joint where rotary actions of supination and pronation occur and this joint is therefore normally regarded as part of the wrist.

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