This is a left lateroposterior view of a dissection with windows through the skull to expose various sutures and intracranial structures. The asterion is a craniometric point at the intersection of the lambdoid, parietomastoid, and occipitomastoid sutures. The interior of the mastoid process has been removed to expose the labyrinth, facial recess, the facial nerve and its chorda tympani branch. At the junction of the occipital lobe and cerebellum, within the attachment here of the tentorium cerebelli, is the transverse sinus. This continues as the sigmoid sinus at the petrooccipital angle and joins the jugular bulb at the jugular foramen. The superior petrosal sinus drains the cavernous sinus to the transverse sinus near its junction with the sigmoid sinus. (Image courtesy of AL Rhoton, Jr.)