Anterior Perspective of the Medial Pectoral Nerve

Description

Arising from the medial cord of the brachial plexus, the medial pectoral nerve courses anteriorly in the axilla toward the pectoral region, where it characteristically pierces pectoralis minor before distributing to the deep surface of pectoralis major. In an anterior perspective, pectoralis minor lies deep to pectoralis major, running superolaterally from ribs 3 to 5 to the coracoid process, so the nerve’s path can be appreciated as it passes from a more medial, proximal position to a more lateral, distal arborization. Nearby landmarks you would expect in this corridor include the axillary artery and vein deep to the pectoral muscles and the lateral pectoral nerve approaching pectoralis major without typically traversing pectoralis minor. A small but telling relationship. That transmuscular course is why this nerve matters. During axillary surgery, mastectomy, or pectoral dissection for implant placement, medial pectoral nerve injury can denervate pectoralis minor and part of pectoralis major, producing medial breast or implant contour changes and weakness with shoulder adduction and internal rotation. The same anatomy explains why a pectoral nerve block (PECS I) placed between pectoralis major and minor often targets the lateral pectoral nerve more reliably, while deeper spread toward the plane deep to pectoralis minor is needed to capture the medial pectoral nerve branches. Needle plane choice matters. Use this illustration to teach brachial plexus terminal branches in gross anatomy and regional anesthesia modules, or to support operative atlases discussing axillary node dissection, pectoralis minor release, and anterior chest wall approaches. It also fits radiology and ultrasound education when correlating the pectoral fascial planes with nerve trajectories. Anatomical accuracy verified by SciePro's Medical Advisory Board.