Axillary Nerve

Origin: Terminal branch of posterior cord, receiving fibers from C₅, C₆

Course: Exits axillary fossa posteriorly, passing through quadrangular space with posterior circumflex humeral artery; gives rise to superior lateral brachial cutaneous nerve; then winds around surgical neck of humerus deep to deltoid

Structures Innervated: Glenohumeral (shoulder) joint; teres minor and deltoid muscles; skin of superolateral arm (over inferior part of deltoid)