Radial Nerve GÇö Branches and Distribution

Radial Nerve — Branches and Distribution

Overview

The radial nerve gives branches throughout its course — in the axilla, in the radial groove, and in the anterior compartment of the arm. It terminates as two branches in the cubital fossa.

Branches Given in the Axilla

Branch	Type	Distribution
Posterior cutaneous nerve of the arm	Cutaneous	Skin of the back of the arm, extending to the olecranon
Muscular branches to long head of triceps	Motor	Long head of triceps brachii
Muscular branches to medial head of triceps	Motor	Medial head of triceps brachii

Branches Given in the Radial (Spiral) Groove

Branch	Type	Distribution
Muscular branches to lateral head of triceps	Motor	Lateral head of triceps brachii
Muscular branches to medial head of triceps	Motor	Additional branch to medial head of triceps
Nerve to anconeus	Motor	Anconeus muscle
Lower lateral cutaneous nerve of the arm	Cutaneous	Lower lateral aspect of the arm
Posterior cutaneous nerve of the forearm	Cutaneous	Posterior (dorsal) surface of forearm from elbow to wrist

Branches Given in the Anterior Compartment of the Arm (Below Lateral Intermuscular Septum)

Branch	Type	Distribution
Muscular branch to brachialis	Proprioceptive (sensory only)	Proprioception from brachialis — no motor supply
Muscular branch to brachioradialis	Motor	Brachioradialis
Muscular branch to extensor carpi radialis longus	Motor	Extensor carpi radialis longus
Articular branches	Sensory	Elbow joint

Terminal Branches (Cubital Fossa, Below Lateral Epicondyle)

1. Deep Branch = Posterior Interosseous Nerve

• Pure motor nerve (with articular branches to wrist)
• Winds around lateral side of neck of radius through supinator muscle
• Supplies all muscles of the back of forearm except brachioradialis, ECRL, and anconeus (already supplied directly)

2. Superficial Branch (Superficial Radial Nerve)

• Pure sensory nerve
• Continues down the anterior forearm under brachioradialis
• Emerges posteriorly in the lower forearm
• Supplies the lateral half of dorsum of hand and dorsal aspect of lateral 3½ digits (proximal phalanges only)

Key Summary Points

• Radial nerve is the nerve of the posterior compartment of the arm and forearm
• Gives no branches in the forearm itself (its terminal branches do the work)
• Triceps receives branches from the nerve both in the axilla (long and medial heads) and in the radial groove (lateral and medial heads) — this explains why triceps is partially spared in radial groove injuries
• Brachioradialis and ECRL are supplied directly by the radial nerve — not by the posterior interosseous nerve