Innervation
  • Motor
    • radial nerve proper 
    •  triceps
      •  anconeus
      •  ECRL
      •  ECRB
      •  brachioradialis  
    • PIN
      •  ED
      •  supinator
      •  EDM
      •  ECU
      •  APL
      •  EPL
      •  EPB
      •  EIP
  • Sensory
    • posterior cutaneous nerve arm
    • posterior cutaneous nerve - forearm
    • superficial branch radial nerve
    • dorsal digital branch
Origin
  • Radial nerve originates from the posterior cord of the brachial plexus (C5-T1)
    • behind axillary artery
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
 

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Questions (1)

(OBQ11.147) During recovery for a radial nerve palsy, what is the last muscle to be reinnervated? Review Topic

QID:3570
1

Brachioradialis

3%

(30/1070)

2

Extensor indicis proprius

79%

(846/1070)

3

Extensor carpi radialis brevis

5%

(50/1070)

4

Abductor pollicis longus

6%

(59/1070)

5

Extensor pollicis longus

7%

(80/1070)

Select Answer to see Preferred Response

PREFERRED RESPONSE 2

The last muscle to demonstrate evidence of reinnervation during recovery for a radial nerve palsy is the extensor indicis proprius.

Abrams et al dissected 20 cadavers to identify the motor branches of the radial nerve. They determined the innervation order from proximal to distal was brachioradialis, extensor carpi radialis longus, supinator, extensor carpi radialis brevis, extensor digitorum communis, extensor carpi ulnaris, extensor digiti quinti, abductor pollicis longus, extensor pollicis longus, extensor pollicis brevis, and extensor indicis proprius (Illustration A).

ILLUSTRATIONS:

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