1. MUSCLES OF FOREARM (BACK)

5. EXTENSOR RETINACULUM

7. ANATOMICAL SNUFF BOX Boundaries:
Lat: Abductor pollicis longus & extensor pollicis brevis (1st compartment of extensor retinaculum).
Med: extensor pollicis longus (3rd compartment of extensor retinaculum).
Floor: styloid process of radius & scaphoid bone.
Roof: superficial fascia containing superficial radial N.
Contents:
• Radial A.
• Ext carpi radialis longus and brevis (2nd compartment of extensor retinaculum).

8. RADIAL NERVE

9. Root value: C5,6,7,8,T1.
Begining:
from post cord of brachial plexus.
Course and relations:
- Lies post to axillary and brachial A.
- Passes in lower triangular space.
- Runs in spiral groove.
- Descends in cubital fossa between brachialis and brachioradialis & divides into 2 terminal branches.

11. Injury of radial nerve: (wrist drop)
A] Injury above spiral groove:
Motor:
• Paralysis of triceps & anconeus  loss of elbow extension.
• Paralysis of muscles of back of forearm  wrist drop.
• Paralysis of fingers extensors  fingers drop.
Sensory: loss of sensation of 1st interdigital cleft (post).
B] Injury in Spiral Groove: differs in:
No loss of elbow extension.
C] Injury of Posterior Interosseous N: differs in:
• No loss of elbow extension.
• Weak extension of wrist (only by extensor carpi radialis longus).
• No sensory loss.