Axillary nerve

The axillary nerve is a nerve in the armpit. It comes from the brachial plexus. It has nerve fibers from the C5 and C6 nerve roots. The axillary nerve goes through the quadrangular space. It is sometimes called the circumflex nerve.

Brachial plexus. Axillary nerve is visible in gray near center

The suprascapular, axillary, and radial nerves. (Axillary labeled at upper right

Function

The axillary nerve sends and receives signals from three muscles in the arm: deltoid (a muscle of the shoulder), teres minor (one of the rotator cuff muscles) and the long head of the triceps brachii.

The axillary nerve sends signals to two muscles in the forearm, and to muscles in the hand. The axillary nerve also sends signals to the brain from the shoulder joint, and from the skin.

Injuries and problems

The axillary nerve can get injured from shoulder dislocation, squashing the armpit using a crutch or a broken arm. Injury to the nerve results in:

• Paralysis (meaning it can't move) of the teres minor muscle and deltoid muscle, resulting in trouble moving the arm. Paralysis of deltoid and teres minor muscles results in flat shoulder deformity.
• Loss of feeling in the skin over a small part of the lateral upper arm.