The sternal head of pectoralis major is the larger, more powerful component, originating from the sternum and costal cartilages. It forms the deep lamina of the pectoralis tendon and inserts on the inferior portion of the bicipital groove lip. It is the primary sternal component involved in pectoralis major rupture.
| Origin | Anterior surface of the sternum and upper six costal cartilages |
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| Insertion | Lateral lip of the bicipital groove via the deep lamina of the pectoralis major tendon |
| Nerve Supply | Medial pectoral nerve (C7, C8, T1) — primarily supplies the sternal head |
| Blood Supply | Pectoral branch of the thoracoacromial artery; Lateral thoracic artery |
| Actions | Adducts the shoulder; Medially rotates the humerus; Extends the shoulder from flexion (via sternal head) |
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Pectoralis major rupture typically involves the sternal head at its humeral insertion, producing the characteristic anterior axillary fold deformity and web sign with arm abduction. Acute repair of the sternal head via tendon-to-bone fixation at the bicipital groove produces the best functional outcomes. EMG differentiates medial pectoral nerve injury (sternal head loss) from lateral pectoral nerve injury (clavicular head loss).
Palpable as the lower, larger bulk of the anterior axillary fold, distinct from the clavicular head above it.
Complete tear of the sternal head at the humeral insertion from forceful eccentric loading (bench press, fall on outstretched arm) producing anterior axillary fold asymmetry and web sign, repaired acutely by tendon-to-bone fixation.
