The Morphological Structure of the Superior Lateral Brachial Cutaneous Nerve Viewed Laterally

Description

Arising from the axillary nerve in the posterior compartment of the axilla, the superior lateral brachial cutaneous nerve courses laterally and inferiorly toward the surgical neck of the humerus, then pierces the deep fascia to reach the subcutaneous tissue over the deltoid region. Seen from a lateral perspective, its superficial branch fans across the skin of the superior lateral arm, just inferior to the acromion, running anterior to the posterior border of the deltoid and lateral to the long head of triceps brachii. Deep to this cutaneous emergence, the deltoid overlies the glenohumeral joint while trapezius and the rotator cuff muscles (supraspinatus and infraspinatus, with teres minor nearby) define the posterior shoulder contour. Small structure, big clinical footprint. That fascial penetration point is the landmark. The superior lateral brachial cutaneous nerve is the sensory correlate of axillary nerve integrity, so numbness over the “regimental badge” area after anterior shoulder dislocation or fracture of the surgical neck of the humerus strongly localizes the lesion. Surgeons also track this nerve during deltoid-splitting approaches and intramuscular deltoid injections, where too distal or posterior placement increases the risk of neurapraxia or painful neuroma. Use this illustration in upper limb anatomy labs, peripheral nerve teaching modules, and orthopaedic or sports medicine texts covering axillary nerve injury patterns and safe deltoid injection zones, and in operative atlases to orient the relationship between the deltoid raphe, deep fascia, and superficial sensory territory. Anatomical accuracy verified by SciePro's Medical Advisory Board.