Axillary nerve

The axillary nerve is a major peripheral nerve of the upper limb, originating from the posterior cord of the brachial plexus and containing fibers from the C5 and C6 spinal nerves (StatPearls: NBK459224). It provides essential motor innervation to the deltoid and teres minor muscles, which are responsible for shoulder abduction and external rotation, respectively (Wikipedia: Axillary nerve). Additionally, it supplies sensory innervation to the glenohumeral joint and the skin overlying the lower portion of the deltoid muscle (StatPearls: NBK459224). While the nerve itself is an anatomical structure rather than a molecular receptor, it is a primary target for regional anesthesia, where local anesthetics like bupivacaine are used to block signal transmission for perioperative pain management (PubMed: 30035230). Clinical pathology often involves axillary nerve palsy resulting from shoulder dislocations or proximal humerus fractures, leading to significant functional impairment and deltoid atrophy (NIH: PMC7354762). Diagnostic assessment of the nerve's integrity is typically conducted through electromyography and nerve conduction studies to evaluate axonal damage (StatPearls: NBK532951). Surgical procedures in the shoulder region require precise knowledge of the nerve's course through the quadrangular space to prevent iatrogenic injury (PubMed: 25103601).

Other names

Circumflex nerve

Local anesthetics interact with the nerve by binding to and inhibiting voltage-gated sodium channels along the axonal membrane, which prevents the influx of sodium ions, inhibits depolarization, and blocks the conduction of action potentials.