The structure indicated is the suspensory ligament of the breast, also known as Cooper’s ligaments.

These ligaments are formed from the connective tissue stroma which surround the ducts and lobules of the mammary gland – in certain areas the connective tissue condenses forming ligaments which support the breast, extending from the dermis of the overlying skin to the deep fascia. These suspensory ligaments support the breast on the chest wall.

The suspensory ligaments of Cooper give rise to the dimpling appearance (peau d’orange) that is seen following development of inflammatory carcinoma, as the lymphatic ducts become blocked and the skin remains tethered by the ligaments.