Anatomy of the Sternal Origin of the Pectoralis Major: Implications for Subpectoral Augmentation

BACKGROUND: The pectoralis major typically is manipulated for implant coverage and pocket design in subpectoral breast augmentation. An understanding of its anatomy can guide successful creation of the implant pocket. OBJECTIVES: The authors evaluated the anatomy of the sternal origin of the pectoralis major to inform surgical planning, help establish a technique for subpectoral augmentation mammaplasty, and identify the most common locations of perforators. METHODS: The sternal origins of 24 pectoralis major muscles were dissected and examined in 15 female cadavers to determine the structure and width of the pectoralis major sternal origin and its relationship to the locations of internal mammary perforators. RESULTS: The average width of the sternal origin of the pectoralis major was 7.1 mm (range, 3 mm-1.8 cm). This width decreased slightly from the second rib to the second intercostal space and then increased progressively in the caudal direction toward the fifth rib. The sternal origin terminated an average of 5.4 mm (range, 1-16 mm) from the midline, with the greatest distance at the fifth rib and large variability throughout. A row of perforators from the internal mammary artery traversed the subpectoral space an average of 2.7 cm from the midline (range, 1-3.7 cm). CONCLUSIONS: The sternal origin of the pectoralis major was thin and highly variable, suggesting that its partial release for implant medialization during subpectoral augmentation is unsafe.