Axillary Nerve

Question 1

Spinal roots

Answer 1

C5 and C6

Question 2

Sensory function

Answer 2

Gives rise to superior lateral cutaneous nerve, which innervates the skin over the lower deltoid (regimental badge area)

Question 3

Motor function

Answer 3

Innervates teres minor - external rotation of upper limb

Innervates deltoid - abduction of upper limb at glenohumeral joint

Question 4

Divisions

Answer 4

In the posterior scapular region, the axillary nerve terminates and divides into…
Posterior terminal branch - provides motor innervation to teres minor and innervates the skin over the inferior deltoid
Anterior terminal branch - provides motor innervation to the deltoid

Question 5

Axillary nerve injury

Answer 5

Motor function - inability to abduct the affected limb
Sensory function - loss of sensation over regimental badge area
Clinical signs - deltoid rapidly atrophies so the greater tuberosity can be palpated in that area