AXILLARY NERVE

• Also known as Circumflex nerve.
• Axillary nerve is a branch of the posterior cord of brachial plexus with root value C5 & C6.
• It leaves the posterior wall of axilla along with the posterior circumflex humeral vessels through the quadrangular space.
• While passing through the quadrangular space it gives its first branch, an articular twig to the shoulder joint.

Then it divides into:

1) Anterior division:- Around surgical neck of humerus to supply deltoid.

2) Posterior division: It gives of:

1. Branches to posterior part of deltoid
2. Nerve to teres minor which shows a pseudoganglion
3. Upper lateral cutaneous nerve of arm supplying the skin covering lower part of deltoid (regimental badge region).

Damage to axillary nerve causes :

1. deltoid paralysis
2. teres minor paralysis
3. loss of rounded contour of shoulder
4. sensory loss in small patch of skin & on the outer surface of arm
5. There is loss of abduction from 15-90 degree due to paralysis of deltoid (first 15 degree of flexion is not lost as it is caused by supraspinatus & overhead abduction is preserved as it is caused by trapezius & serratus anterior).