Radial Nerve

Innervation

Motor
- radial nerve proper
  - triceps
  - anconeus
  - ECRL
  - ECRB
  - supinator
  - brachioradialis
- PIN
  - ED
  - EDM
  - ECU
  - APL
  - EPL
  - EPB
  - EIP
Sensory
- posterior cutaneous nerve arm
- posterior cutaneous nerve – forearm
- superficial branch radial nerve
dorsal digital branch

Origin

Course

Posterior wall axilla
- courses on the posterior wall of the axilla (on subscapularis, latissimus dorsi, teres major)
- 3 Branches in axilla
  - posterior cutaneous nerve of the arm
  - branch to long head of triceps
  - branch to medial head of triceps
Triangular interval
- it then runs through the triangular interval with profunda brachii artery in posterior compartment between long head of triceps and humerus
Spiral groove
- next it courses through the spiral groove between lateral and medial heads of triceps
  - bottom line = Safe zone posteriorly of 10 cm distal to the lateral acromion and 10 cm proximal to lateral epicondyle
- branches in spiral groove
  - inferior lateral cutaneous nerve of the arm
  - posterior cutaneous nerve of the forearm
  - branch to lateral head of triceps
  - branch to medial head of triceps and anconeus
Lateral intermuscular septa
- next it passes through the lateral intermuscular septa never less than 7.5 cm above the distal articular surface.
- runs between brachialis and brachioradialis (anterior to lateral epicondyle)
  - gives branches to supply: lateral brachialis, brachioradialis, ECRL, ECRB
Terminal branches
- level of radiohumeral joint line, divides into terminal branches
  - superficial sensory branch
  - Deep branch/PIN
ECRB branch

Injury & Clinical Conditions

PIN compression Syndrome
Radial Tunnel Syndrome
Radial claw hand
- injury to the radial nerve with characteristic “claw” hand involving the loss of wrist extension and finger extension