Download 1 - Pass the FracP

RNSH 2003 NEUROLOGY QU.1
20 yo man, traumatic shoulder injury (rugby), not dislocated. O/E shoulder
abduction 4/5, external rotation 3/5, patchy sensory loss lateral forearm. Nature of
injury?
a) axillary nerve
b) musculocutaneous nerve
c) C5 root
d) Upper brachial plexus
e) Long thoracic nerve
AXILLARY NERVE (C5, C6):
Comes off posterior cord of brachial plexus, through the posterior wall of the axilla
Supplies deltoid (shoulder abduction) and teres minor (lateral rotation of the humerus at
the shoulder joint, in conjunction with infraspinatus), the shoulder joint, and the skin
overlying the lower part of deltoid
Damage can occur during dislocation of the shoulder joint, leading to weak abduction,
impaired sensation and eventual wasting of deltoid muscle
MUSCULOCUTANEOUS NERVE (C5, C6, C7):
Comes off lateral cord of brachial plexus, lateral to the fascia of the axillary floor
Supplies muscles of the anterior compartment of the arm – biceps (strong flexor of the
elbow and supinator of the forearm at the radioulnar joints, weak flexor of the shoulder
joint), coracobrachialis (weak flexor and adductor of the shoulder joint) and brachialis
(strong flexor of elbow joint)
Continues distally as the lateral cutaneous nerve of the forearm, supplying the lateral
forearm
SHOULDER ABDUCTION:
Initiated by supraspinatus (supplied by suprascapular nerve, which arises from the upper
trunk of the brachial plexus), maintained by deltoid
EXTERNAL ROTATION:
Infraspinatus (supplied by suprascapular nerve) and teres minor
The guy would have had to have a neck injury to affect just C5
The long thoracic nerve has nothing to do with the shoulder and sensation in the lateral
forearm, so I’m not even going to try to trawl through my anatomy book to describe it in
detail!
I think the answer that makes most sense is the upper brachial plexus – this implies that
there could be damage to the upper cord, with repercussions on the suprascapular nerve
and the musculocutaneous nerve, so I’m going with D.