Axillary Nerve
The axillary nerve arises from the posterior cord of the brachial plexus and traverses the quadrangular space to supply motor innervation to the deltoid muscle and sensory innervation to its cutaneous distribution. Clinical injury mechanisms include fractures of the surgical neck of the humerus or inferior shoulder dislocations, which compromise vascular structures accompanying the nerve within this anatomical boundary. Dysfunction resulting from these injuries manifests clinically as paralysis preventing shoulder abduction extension coupled with specific areas of dermal anesthesia on the upper lateral arm surface.
Quadrangular Space and Triangular Interval Neurovascular Anatomy of the Upper Limb
This concept covers the anatomical definition and neurovascular contents of two spaces in the posterior shoulder/axillary region: the quadrangular space, bounded laterally by the humerus and medially…