Radial Nerve Anatomy
Episode 1
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
Cutaneous Innervation
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Posterior cutaneous nerve of arm
Inferior lateral cutaneous nerve of arm
Posterior cutaneous nerve of forearm
Superficial branch of radial nerve
Motor Innervation
• Muscular branches of radial nerve above
elbow:
– Triceps
– Anconeus
– Brachoradialis
– ECRL
Motor Innervation
• Muscular Branches below elbow:
– ECRB (varied innervation: superficial or PIN)
– Supinator
• PIN:
– Superficial
• EDC, ECU,, EDM
– Deep
• APL, EPL, EPB, EI
Course of Radial Nerve
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
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
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
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
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
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)
Posterior Interosseous Nerve
• After exiting the supinator divides into deep
and superficial muscular branches
– Superficial
• EDC, ECU, EDM
– Deep
• APL, EPL, EPB, EI
Radial Nerve Compression Sites
• PIN
– As it traverses the radial tunnel it encounters 4
sites of compression
– “Radial tunnel syndrome”
• entrapment neuropathy
Radial Tunnel Syndrome
1. Fibrous bands
•
Tight fibrous bands anterior to radial head at entrance of
tunnel
2. Arcade of Frohse
•
Most common
3. Leash of Henry
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Radial recurrent vx that fan out over radial nn
4. Medial border of ECRB
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
Radial Nerve Palsy
• Causes:
– Fractures esp humerus, Monteggia
– Penetrating injury/trauma
– “Saturday Night Palsy” “Crutches”
– Iatrogenic
– tumour
Episode II
Radial Nerve Tendon Transfers