Radial Nerve Anatomy

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Radial Nerve AnatomyEpisode 1

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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

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Cutaneous Innervation

• Posterior cutaneous nerve of arm
• Inferior lateral cutaneous nerve of arm
• Posterior cutaneous nerve of forearm
• Superficial branch of radial nerve

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Motor Innervation

• Muscular branches of radial nerve above elbow
• Triceps
• Anconeus
• Brachoradialis
• ECRL

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Motor Innervation

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

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Course of Radial Nerve
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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

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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

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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

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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

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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

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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)

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Posterior Interosseous Nerve

• After exiting the supinator divides into deep and
  superficial muscular branches
• Superficial
• EDC, ECU, EDM
• Deep
• APL, EPL, EPB, EI

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Radial Nerve Compression Sites

• PIN
• As it traverses the radial tunnel it encounters 4
  sites of compression
• Radial tunnel syndrome
• entrapment neuropathy

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Radial Tunnel Syndrome

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

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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

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Radial Nerve Palsy

• Causes
• Fractures esp humerus, Monteggia
• Penetrating injury/trauma
• Saturday Night Palsy Crutches
• Iatrogenic
• tumour

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Episode IIRadial Nerve Tendon Transfers