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