Axillary nerve

Axillary nerve
Brachial plexus. (Axillary nerve is visible in gray near center.)
The suprascapular, axillary, and radial nerves. (Axillary labeled at upper right.)
Details
From	posterior cord (C5, C6)
Innervates	deltoid, teres minor, axilla
Identifiers
Latin	nervus axillaris
Dorlands /Elsevier	n_05/12565259
TA	A14.2.03.059
FMA	37072
Anatomical terms of neuroanatomy []

The axillary nerve or the circumflex nerve is a nerve of the human body, that originates from the brachial plexus (upper trunk, posterior division, posterior cord) at the level of the axilla (armpit) and carries nerve fibers from C5 and C6. The axillary nerve travels through the quadrangular space with the posterior circumflex humeral artery and vein.

The nerve lies at first behind the axillary artery, and in front of the subscapularis, and passes downward to the lower border of that muscle.

It then winds backward, in company with the posterior humeral circumflex artery, through a quadrangular space bounded above by the teres minor, below by the teres major, medially by the long head of the triceps brachii, and laterally by the surgical neck of the humerus, and divides into an anterior, a posterior, and a collateral branch to the long head of the triceps brachii branch.

The axillary nerve supplies 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. Traditionally, the axillary nerve was thought to only supply the deltoid and teres minor. However, a study conducted in 2004 determined that, in 20 cadaveric specimens and 15 surgical dissections on participants, the long head was innervated by a branch of the axillary nerve in all cases.

The axillary nerve also carries sensory information from the shoulder joint, as well as the skin covering the inferior region of the deltoid muscle - the "regimental badge" area (which is innervated by the superior lateral cutaneous nerve branch of the axillary nerve).