The radial nerve originates from cervical and thoracic nerve roots and is the largest branch of the brachial plexus. It provides cutaneous innervation to the posterior arm and forearm and motor innervation to triceps, brachioradialis, and extensor muscles of the forearm and hand. The radial nerve is vulnerable to compression at the radial tunnel as it travels through the forearm. Compression can cause radial tunnel syndrome. The superficial branch of the radial nerve can be affected by Wartenberg syndrome. Radial nerve palsy can result from fractures, injuries, tumors, or iatrogenic causes.

2. Radial Nerve Anatomy
Episode 1

3. Radial Nerve
• Originates as the terminal branch of the
posterior cord of the brachial plexus:
– roots from C5, 6, 7, 8, & T1.
– Largest branch of brachial plexus

5. Cutaneous Innervation
• Posterior cutaneous nerve of arm
• Inferior lateral cutaneous nerve of arm
• Posterior cutaneous nerve of forearm
• Superficial branch of radial nerve

8. Motor Innervation
• Muscular branches of radial nerve above
elbow:
– Triceps
– Anconeus
– Brachoradialis
– ECRL

9. Motor Innervation
• Muscular Branches below elbow:
– ECRB (varied innervation: superficial or PIN)
– Supinator
• PIN:
– Superficial
• EDC, ECU,, EDM
– Deep
• APL, EPL, EPB, EI

10. Course of Radial Nerve

11. Course of Radial Nerve
• Largest terminal branch of posterior cord
• Enters posterior aspect of humerus through lower
triangular interval
– Teres major (superior)
– Long head triceps (medial)
– Humerus (lateral)
• Gives posterior cutaneous nerve of arm in axilla

13. Course of Radial Nerve
• Comes to lie in distal part of spiral groove with
profundi brachii artery
– Beneath lateral head of triceps and proximal to origin of
medial head
• Gives branches to triceps, anconeus and inferior
lateral cutaneous nerve of arm
• Through lateral intermuscular septum 10-12cm
above lateral epicondyle

15. Course of Radial Nerve
• In anterior compartment of arm lies between
brachialis and brachioradialis
– 1-3 accessory branches to brachialis
– Large branch to BR (sometimes this branch given
by superficial radial below elbow)
• ECRL generally innervated proximal to elbow
joint

17. Course of Radial Nerve
• Enters the forearm anterior to lateral epicondyle
– More specifically over articulation between capitulum and
radial head
• ECRB innervated distal to elbow joint either PIN or
superficial branch
• At some point 3cm above or below divides into:
– Superficial radial
– PIN

19. Course of Superficial Radial Nerve
• Runs over supinator,PT and FDS
• Lies under BR with radial artery on its ulnar side from
1/3 of the way down forearm
• Passes posteriorly through tendon of BR proximal to
radial styloid
• Passes over tendons of snuffbox
• Terminates as cutaneous branches to dorsum of
hand and lateral 3.5 digits short of nailbeds

22. Posterior Interosseous Nerve
• Gains access to posterior forearm by diving
posterior and laterally through ligament of
Frohse and the interval between the two
heads of supinator
• Arcade of Frohse is a fibrous arch originating
lateral epicondyle superior part of superficial
layer of supinator
– German Anatomist, Fritz Frohse (1871-1916)

26. Posterior Interosseous Nerve
• After exiting the supinator divides into deep
and superficial muscular branches
– Superficial
• EDC, ECU, EDM
– Deep
• APL, EPL, EPB, EI

27. Radial Nerve Compression Sites
• PIN
– As it traverses the radial tunnel it encounters 4
sites of compression
– “Radial tunnel syndrome”
• entrapment neuropathy

28. Radial Tunnel Syndrome
1. Fibrous bands
• Tight fibrous bands anterior to radial head at entrance of
tunnel
1. Arcade of Frohse
• Most common
1. Leash of Henry
• Radial recurrent vx that fan out over radial nn
1. Medial border of ECRB

29. Cheiralgia paresthetica
• Described by Robert Wartenberg 1932
• Superficial radial nerve neuritis
– Wartenberg Syndrome
• Causes:
– Trauma, iatrogenic, compression (muscle anomalies,
fascial bands, thrombosis radial recurrent artery, tumour,
haemorrhage)
• Symptoms:
– Dysaesthesia over distribution

30. Radial Nerve Palsy
• Causes:
– Fractures esp humerus, Monteggia
– Penetrating injury/trauma
– “Saturday Night Palsy” “Crutches”
– Iatrogenic
– tumour

36. Episode II
Radial Nerve Tendon Transfers