[1][2][3] The axillary nerve travels through the quadrangular space with the posterior circumflex humeral artery and vein to innervate the deltoid and teres minor.

The nerve lies at first behind the axillary artery,[4] and in front of the subscapularis,[1] and passes downward to the lower border of that muscle.

However, several studies on cadavers pointed out that the long head of triceps brachii is innervated by a branch of the axillary nerve.

The posterior cord of the brachial plexus splits inferiorly to the glenohumeral joint giving rise to the axillary nerve which wraps around the surgical neck of the humerus, and the radial nerve which wraps around the humerus anteriorly and descends along its lateral border.

The axillary nerve may be injured in anterior-inferior dislocations of the shoulder joint, compression of the axilla with a crutch or fracture of the surgical neck of the humerus.