Anatomy of Hand and Wrist 4 Assistant professor Dr. Alaa A. Alharba Orthopedic &Hand Surgeon

The regions of the Wrist

Anterior aspect of the wrist The following structures pass superficial to the flexor retinaculum from medial to lateral: Flexor carpi ulnaris tendon ending on the pisiform bone. Ulnar nerve lies lateral to the pisiform bone. Ulnar artery lies lateral to the ulnar nerve.

Structures that pass superficial to the flexor retinaculum from medial to lateral(continued) 4. Palmar cutaneous branch of the ulnar nerve. 5. Palmaris longus tendon (if present) passing to its insertion into the flexor retinaculum and pamar aponeurosis. 6. Palmar cutaneous branch of median nerve.

v The structures passing beneath the flexor retinaculum from medial to lateral: Flexor digitorum superficialis tendons(FDS). Flexor digitorum profundus tendons(FDP) passing deeply to the tendons of FDS. Both groups of tendons share a common synovial sheath. Median nerve. Flexor pollicis longus tendon(FPL) surrounded by a synovial sheath. Flexor carpi radialis tendon(FCR) through a split in the flexor retinaculm. The tendon is surrounded by a synovial sheath.

Posterior aspect of the Wrist: the following structures passing superficial to the extensor retinaculum from medial to lateral: Posterior cutaneous branch of the ulnar nerve. Basilic vein. Cephalic vein. Superficial branch of radial nerve.

The extensor retinaculum send fibrous septa pass to the underlying radius and ulna and form six compartments that contain the tendons of the extensor muscles. Each compartment is provided with a synovial sheath , which extends above and below the retinaculum.

Synovial Sheath: It is a tubular bursa that surrounds a tendon. The tendon invigilates this bursa from one side so that the tendon becomes suspended within the bursa by a mesotendon. The mesotendon enables blood vessels to enter the tendon along its course. Synovial sheath occur where tendons pass under ligaments and retinacula and through osteofascial tunnels. Function is to reduce friction between the tendon and the surrounding structures

Wrist Joint ( Radio Carpal Joint)

Wrist Joint: Articulation between the distal end of the radius above (proximal articular surface) and the scaphoid, lunate and triquetral bones below ( distal articular surface). Type: synovial ellipsoid joint: the proximal articular surface is concave which is adapted to the distal convex surface. Capsule: encloses the joint and is attached above to the distal ends of the radius and ulna and below to the proximal row of the carpal bones.

Wrist joint Ligaments: anterior and posterior ligaments strengthen the capsule. The medial ligament attached to the styloid process of the ulna and to the triquetral bone. Lateral ligament is attached to the styloid process of the radius and to the scaphoid bone.

Wrist Joint: Synovial membrane: it lines the capsule and attached to the margins of the articular surfaces. The joint cavity of the wrist joint does not communicate with the distal radioulnar joint or with the joint cavities of the intercarpal joints. Nerve Supply: anterior interosseous nerve and the deep branch of the radial nerve.

Movements: Flexion , Extension, Abduction, Adduction. The rotation is not possible and compensated by supination and pronation of the forearm. Flexion: performed by FCR, FCU, and Palmaris longus, assisted by FDP, FDS, and FPL. Extension: by ECRL, ECRB, ECU, and assisted by AbPL, EPL and EPB. Abduction: by FCR, ECRL, and ECRB. Adduction: by FCU and ECU.

Wrist Joint Important Relations: Anteriorly: the tendons of FDP, FDS, FPL, FCR, FCU, and the median and ulnar nerve. Posteriorly: the tendons of ECU, EDM, ED, EI, ECRL, ECRB, and AbPL. Medially: the posterior cutaneous branch of the ulnar nerve. Laterally: the anatomic snuffbox and the radial artery.

Anatomic Snuffbox: Is a term commonly used to describe a triangular skin depression in the lateral side of the wrist that is bounded medially by the tendon of the extensor pollicis longus and laterally by the tendons of the abductor pollicis longus and extensor pollicis brevis. Its importance lies in the fact that scaphoid bone is most easily palpated here and that the pulsation of the radial artery can be felt here.

Anatomic Snuffbox: Bony points readily palpable in the snuffbox are the radial styloid proximally and the base of the thumb metacarpal distally. between the two the scaphoid and trapezium can be felt. In the floor of the snuffbox the cutaneous branches of the radial nerve cross these tendons. The cephalic vein begins in the snuffbox from radial side of the dorsal venous network( arch). The radial artery is deep to all three tendons lies in the floor.

Surface anatomy of the Wrist Joint: Styloid process of the radius and ulna can be palpated. The styloid process of the radius lies about (1.9cm) distal to the styloid process of the ulna. Dorsal tubercle of the radius is palpable on the posterior surface of the distal end of the radius. The head of the ulna is easily felt with the forearm pronated , the round head of the ulna become prominent and distinguished from more distal pointed styloid process. Pisiform bone can be felt on the medial side of the anterior aspect of the wrist between the two transverse creases. The hook of the hamate felt on deep palpation of the hypothenar eminence ( distal and lateral to the pisiform bone). The proximal transverse crease lies at the level of the wrist joint, while the distal transverse wrist crease lies corresponds to the proximal border of the flexor retinaculum.