1. POSTERIOR ANTEBRACHIUM

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

3. 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

4. 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.

5. 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.

6. 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.

7. 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.

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

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

10. 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

12. 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