Left lateral transmastoid view of bony labyrinth, sigmoid sinus, and cerebellum after mastoidectomy. Mastoidectomy and dural excision at Trautmann's triangle reveal the sigmoid sinus, which continues as the jugular bulb, and the lateral surfaces of the cerebrum and cerebellum. The superior petrosal sinus lies inferior to the vein of Labbe and drains the cavernous sinus to the transverse sinus. The anastomotic vein of Labbe drains a portion of the temporal lobe and connects the superficial middle cerebral vein to the transverse sinus as well. Trautmann's triangle is shown bounded by the bony labyrinth anteriorly, the sigmoid sinus posteriorly, and the superior petrosal sinus superiorly. 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.)