Axillary Nerve

Question 1

What are the spinal roots?

Answer 1

C5, C6

Question 2

What are the motor functions?

Answer 2

Innervates the teres minor and deltoid muscles.

Question 3

What are the sensory functions?

Answer 3

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

Question 4

Describe the anatomical course

Answer 4

• It is a direct continuation of the posterior cord of the brachial plexus, and therefore contains fibres from the C5 and C6 nerve roots
• It descends to the inferior border of the subscapularis muscle, and then exits the axilla posteriorly via the quadrangular space. It is accompanied by the posterior circumflex humeral artery.

In the posterior scapular region, the axillary nerve terminates by dividing into two branches:

Posterior terminal branch – Provides motor innervation to the teres minor muscle, and innervates the skin over the inferior part of the deltoid.

Anterior terminal branch – Provides motor innervation to the deltoid muscle