Pectoralis Minor Muscle

Description

Beneath the anterior breast parenchyma, the pectoralis minor lies deep to pectoralis major and courses superolaterally from the 3rd to 5th ribs toward the coracoid process, forming a muscular plane posterior to the retromammary space. Superficial to that chest wall layer, the cut section of the mamma shows lobules and glandular tissue embedded in adipose, with lactiferous ducts converging anteriorly toward the nipple-areolar complex and fibrous suspensory septa (Cooper ligaments) tethering skin to the deep fascia. Small arteries and veins track within the stroma and along the glandular units, oriented radially from the deeper chest wall toward the anterior surface. Including pectoralis minor in a breast cross-section matters because it anchors the clavipectoral fascia and defines a key deep landmark when you teach or plan breast and axillary procedures. In modified radical mastectomy and axillary lymph node dissection, exposure and retraction around the pectoralis minor determine access to level II nodes posterior to the muscle, while preserving adjacent neurovascular structures. It also supports interpretation of deep posterior lesions on mammography, ultrasound, or breast MRI, where the retromammary fat plane and pectoral musculature help separate parenchymal findings from chest wall invasion. A clean plane. Use this artwork in breast anatomy and lactation modules, surgical oncology teaching materials (sentinel node mapping, mastectomy planes), and radiology atlases that correlate glandular tissue with the underlying chest wall. It also fits patient-facing counseling diagrams for benign breast disease or postoperative changes when you need to explain what sits immediately deep to the breast. Anatomical accuracy verified by SciePro's Medical Advisory Board.