The surgical anatomy of the scalp. Cadaveric dissections and surgical observations have led to the description and clarification of the boundaries. blood supply, and nomenclature of the layers of the scalp. Special attention was directed to the layer of "loose connective tissue" that lies beneath the entire galea and above the cranial periosteum centrally, and the temporalis fascia laterally. It has been named the subgaleal fascia (SGF). The subgaleal fascia is a trilaminar structure with unusual potential in reconstructive surgery. Histologic study reveals the subgaleal fascia to be composed of a central dense collagenous layer surrounded by vascularized areolar tissue. It is readily dissected from surrounding galeal and periosteal layers. The subgaleal fascia was probably included in previously described "pericranial flaps," which were often based beyond the periosteum. The blood supply of the subgaleal fascia originates from the proximal portion of the peripheral vessels of the scalp and continues within the areolar lamina. The subgaleal fascia is an exceptionally thin, malleable, and well-vascularized flap useful for facial reconstruction. 