A reinterpretation of human breast anatomy includes all the layers of the anterior body wall

Mammary glands define mammals as a group, yet a comprehensive anatomical description of the mammary gland does not exist for almost any mammalian species. In humans, the anatomical and surgical literature provide conflicting and incomplete descriptions of the gross anatomy of the breast. We dissected 9 male and 15 female human body donors to clarify this gross anatomy. We found that, like other epidermally derived glands of the body, the mammary glandular tissue is constrained to a membrane-bound, central structure referred to as the corpus mammae in the surgical literature, and not dispersed throughout the breast as typically described in the anatomical literature. The major fasciae of the human anterior body wall, including the superficial fatty Camper's fascia and the deeper membranous Scarpa's fascia, both contribute to the structure of the breast. This anatomical arrangement suggests that, as the mammary gland invaginates posteriorly from the integument during embryological development, the mammary fat pad most likely derives from Camper's fascia, and growth of Scarpa's fascia around this fat pad forms the anterior and posterior lamellae of the breast pocket. Anteriorly, Scarpa's fascia becomes a double layer that creates the surface structure of the breast. Posteriorly, Scarpa's fascia forms a circummammary ligament that (1) stabilizes the breast against the thoracic wall and (2) is continuous with Scarpa's fascia on the rest of the anterior body wall. The suspensory ligaments of the breast represent the typical retinaculae cuti found consistently throughout the human body wall, and do not directly attach to the skin. Instead, these retinaculae attach to the anterior or posterior lamella of Scarpa's fascia.