Radial Nerve

 What is the origin and root value of radial nerve?  

Origin: Is the largest nerve of the brachial plexus. It arises from posterior cord of brachial plexus.

Root Value: Its root value  is  C5– T1 spinal segments of spinal cord _.:

Describe the course of radial nerve?  

• It arises from the posterior cord of brachial plexus in the axilla
• It enters the posterior compartment of arm at lower border of the teres major through the lower triangular space.
• It then lies in the spiral groove of humerus along with the profunda brachii vessels between the lateral and medial heads of triceps.
• At the lower end of the spiral groove it pierces the lateral intermuscular septum to enter the anterior compartment of arm.
• It then enters the cubital fossa and at the level of lateral epicondyle it terminates by dividing into superficial and deep (posterior interosseous ) branches.
• The superficial branch enters the forearm and runs deep to brachioradialis.
• In the lower 1/3^rd of the forearm it winds around the lateral aspect of radius to reach the anatomical snuff box on the dorsum of hand.
• It terminates by dividing into digital branches.
• The deep (posterior interosseous nerve) branch leaves the cubital fossa by passing through the supinator  to enter the posterior compartment of forearm. 

Name the branches and structures supplied by radial nerve?  

   Branches and distribution:

• In the axilla
  • Sensory branch: Posterior cutaneous nerve of arm ( supplies skin on the back of arm)
  • Motor branches:
    • Nerve to long head of triceps
    • Nerve to medial head of triceps
• In the spiral groove:
  • Sensory branches:
    • Lower lateral cutaneous nerve of the arm ( skin on the lateral surface of arm)
    • Posterior cutaneous nerve of the forearm ( skin of the middle of the back of forearm)
  • Motor branches:
    • Nerve to lateral head of triceps
    • Nerve to medial head of triceps
    • Nerve to anconeus
• In the anterior compartment of arm:
  • Motor branches:
    • Nerve to brachialis (proprioceptive)
    • Nerve to brachioradialis
    • Nerve to extensor carpi radialis longus
• In the cubital fossa (Terminal branches):
  • Superficial branch (sensory branch)
    • Innervates the skin over the lateral part of the dorsum of hand and dorsal surface of lateral 3 ½ digits upto the middle phalanx.
  • Deep (posterior interosseous) branch (motor branch)
    • In the cubital fossa:
      • Extensor carpi radialis brevis
      • Supinator
    • In the posterior compartment of forearm
    • All the extensor muscles of forearm (extensor digitorm, extensor indicis, extensor digiti minimi, externsor carpi ulnaris, abductor pollicis longus, extensor pollicis longus and extensor pollicic brevis)

Applied Aspect