Medial Pectoral Nerve

Description

Emerging from the medial cord of the brachial plexus, the medial pectoral nerve courses anteriorly and inferiorly toward the axilla, then passes through or along the pectoralis minor before distributing to the deep surface of pectoralis major. A communicating loop with the lateral pectoral nerve (ansa pectoralis) spans the region between the clavicle and upper ribs, positioned anterior to the thoracic cage and medial to the humeral head. Surrounding osseous landmarks include the clavicle superiorly, the scapula laterally, and the sternum with costal cartilages medially. Bony context matters. Because the nerve often pierces pectoralis minor, this view clarifies a relationship that drives both teaching and operative planning: the medial pectoral nerve is at risk during axillary dissection and pectoralis minor manipulation, and injury can weaken shoulder adduction and internal rotation by denervating portions of pectoralis major. The illustrated ansa pectoralis also helps explain why pectoral muscle function may be partly preserved after selective nerve injury, and why pain patterns can look inconsistent when the loop is spared. In breast and thoracic surgery, identifying these branches helps avoid postoperative anterior chest wall weakness and reduces traction-related neuropraxia. Use this artwork in gross anatomy and brachial plexus modules to anchor the medial cord branches against fixed thoracic landmarks, or in surgical atlases covering mastectomy, axillary lymph node dissection, and pectoral muscle flap harvest. It also suits radiology and sports medicine teaching when correlating anterior shoulder girdle symptoms with plexus-level lesions rather than isolated intercostal nerve pathology. Anatomical accuracy verified by SciePro's Medical Advisory Board.