Left lateral transmastoid view of bony labyrinth, sigmoid sinus, and cerebellum after mastoidectomy. Mastoidectomy and dural excision  reveal the sigmoid sinus (posteriorly), the lateral surfaces of the cerebrum (reflected superiorly) and cerebellum, and the bony labyrinth (anteriorly). A segment of the superior petrosal sinus has been removed and the vein of Labbe is reflected as well to expose the cerebellum. The anastomotic vein of Labbe drains a portion of the temporal lobe and connects the superficial middle cerebral vein to the transverse sinus. The labyrinth has been opened to visualize the posterior, superior, and lateral semicircular canals. The Spine of Henle or suprameatal spine is located immediately inferior to the root of the zygomatic process of the temporal bone. (Image courtesy of AL Rhoton, Jr.)