Injury to radial nerve in the lower part of spiral groove -
Radial nerve injury

Radial nerve injury may be high or low.

1) High radial nerve palsy

The injury is before the spiral groove
All muscles supplied by radial nerve are paralysed.

2) Low radial nerve palsy

The injury is after the spiral groove.
Low radial nerve palsy may be of two types.

i) Type I: - Injury occurs between the spiral groove and elbows joint. Muscles involvement is : -
a)Elbow extensors (Triceps, anconeus) are spared.
b)Wrist, elbow and finger extensors are paralysed.
c) Sensory loss in first web space (on dorsal side)
ii) Type II: - Injury occurs below the elbow joint.
a) Elbow extensors (triceps, anconeus), Brachioradialis and wrist extensors (ECRL) are spared.
b) Finger extensors (extensor digitorum, extensor digit minimi, extensor indices) and thumb extensors (extensor pollicis longus & brevis) are paralysed.
c) Sensory loss in first web space ( on dorsal side).
Spares nerve supply to extensor carpi radialis longus
Results in paralysis of anconeus muscle
Leaves extensions at elbow joint intact
Weakens pronation movement