Anatomical findings from 28 breast specimens of female corpses have shown a thin horizontal fibrous septum, originating from the pectoral fascia along the level of the fifth rib, heading toward the nipple. This fibrous septum lies in between a cranial and a caudal vascular network, and being mesentery-like, it is responsible for the supply of the nipple areola complex. The cranial vascular sheet is supplied by the thoracoacromial artery and a branch of the lateral thoracic artery, whereas the caudal sheet is supplied by perforating branches from anastomoses of intercostal arteries. The fibrous septum is also a guiding structure for the main supplying nerve of the nipple. At its borders the septum curves upward into a vertical medial and lateral ligament, which attach the breast to the sternum and the lateral edge of pectoralis minor. These ligaments also contain a regular nerve and vascular supply. In their total, the fibrous septum and its ligaments form a sling of dense connective tissue that acts as a brassiere-like suspensory system. These two structures, the fibrous sling and the vascular and nervous membranes attached to it, are consistent anatomical findings, which have not been described before. Their knowledge could be of value and relevance in clinical application.