Neurovascular Relationships of the Medial Temporal Region. I, Superior view of the ventricular surface of the left MTR (same specimen as in part C). The anterior (yellow), middle (green), and posterior (red) segments of the MTR are defined by the colored brackets. The ossicles in the middle ear, semicircular canals, and the superior petrosal sinus are located lateral to the middle segment of the MTR. Understanding these anatomic relationships is critical to performing the presigmoid retrolabyrinthine approach to the middle segment of the MTR. J, Presigmoid approach to the medial temporal lobe. The presigmoid approach lowers the floor of the middle fossa and provides for a lower operative trajectory to the middle segment of the MTR. The approach can be accomplished without opening the labyrinth so that the hearing is preserved. Care is taken to preserve the vein of Labbé. (Images courtesy of AL Rhoton, Jr.)