POSTERIOR ANTEBRACHIUM

Extensor Retinaculum Deep fascia Transversely crosses distal ends of radius and ulna.

Extensor Retinaculum Converts grooves in radius into tunnels for extensor tendons (lateral to medial): Abductor pollicis longus Extensor pollicis brevis Styloid process Extensor carpi radialis longus Extensor carpi radialis brevis Dorsal tubercle Extensor pollicis longus Extensor digitorum and extensor indicis

Radial Nerve Pierces lateral intermuscular septum in lower arm and enters antebrachium between brachioradialis and brachialis muscles. Passes in front of lateral epicondyle and enters cubital fossa. Divides into superficial and deep branches.

Radial Nerve Deep Branch Wraps laterally around radius between superficial and deep layers of supinator. = posterior interosseous nerve. Runs with posterior interosseous artery. Motor to all extensor muscles of the forearm except extensor carpi radialis longus and anconeus.

Radial Nerve Superficial Branch Cutaneous. Accompanies radial artery proximally. Emerges from beneath brachioradialis in distal forearm. Supplies lateral half of dorsum of hand and dorsum of thumb and index finger.

Radial Artery Smallest terminal branch of brachial artery. Proximally lies deep to brachioradialis. Distally becomes superficial between brachioradialis and flexor carpi radialis. Winds dorsally through anatomical snuff-box.

Radial Artery Branches Radial recurrent Dorsal carpal artery Dorsal metacarpal and digital arteries First dorsal metacarpal: Princeps pollicis Radialis indicis

Interosseous Arteries From common interosseous artery from ulnar artery. One on either side of interosseous membrane.

Superficial Muscles Primarily wrist and hand extensors Common origin = lateral epicondyle: Superior to inferior: Brachioradialis Extensor carpi radialis longus Extensor radialis brevis Extensor digitorum (communis) Extensor digiti minimi Extensor carpi ulnaris

Deep Muscles Four muscles emerge from antebrachium between extensor carpi radialis muscles and the extensor digitorum muscle. Three outcropping muscles insert on thumb: Abductor pollicis longus Extensor pollicis brevis Extensor pollicis longus Extensor indicis. Supinator