MUSCULOCUTANEOUS NERVE C5/C6/C7

 

MS Nerve

ORIGIN

  • lateral cordof brachial plexus
  • formed from anterior divisionsof superior and middle trunks

COURSE

  • it leaves the axilla by piercing coracobrachialismuscle
  • it then passes down the arm beneath biceps muscle
  • it ends as the lateral cutaneous nerve of forearm

SENSORY SUPPLY

  • skin of lateral forearm

MOTOR SUPPLY

  • anteriorcompartment of arm (BBC)
    • biceps– flexes elbow, supinates forearm
    • brachialis– flexes elbow
    • coracobrachialis– adducts shoulder, flexes elbow

COMMON INJURIES

  • musculocutaneous nerve injuries are rare, as the nerve is protectedbeneath the bulk of the biceps muscle
  • it may be damaged by stab woundsto the upper arm

CLINICAL FEATURES OF MUSCULOCUTANEOUS NERVE PALSY

  • SENSORY LOSS
    • numbness over lateral forearm
  • MOTOR DEFICIT
    • paralysis of anterior compartment of arm – very weakelbow flexion and weak forearm supination
    • absent biceps reflex
  • DEFORMITY
    • wastingof anterior compartment of arm
    • elbow usually held in extensionwith forearm pronated

 

Reference:

  • http://www.cram.com/flashcards/upper-extremity-special-tests-1246316

 

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