Inferior and Lateral Views of the Temporal Lobe and Optic Radiations. A, Inferior view with the uncus preserved bilaterally. The uncus has an anterior segment and a posterior segment and an apex between the segments that is directed below the optic tract. The amygdala, outlined in green on the left uncus, is positioned largely within the anterior uncal segment. B, Gray and white matter below the temporal horn have been removed to expose the optic radiations and Meyer’s loop. A portion of the left uncus and amygdala (outlined in green) has been preserved. Meyer’s loop passes forward from the lateral geniculate body and reaches the anterior tip of the roof of the temporal horn. The triangular area with the apex at the lateral geniculate body is the area through which the temporal horn can be entered from above through the floor of the sylvian fissure without damaging Meyer’s loop laterally or the optic tract medially. C, Inferior view of the right temporal lobe. The gray and white matter below the temporal horn and optic radiations have been removed. The optic radiations arise from the lateral geniculate body, loop forward in the roof to the anterior tip of the temporal horn, and turn backward around the roof and lateral wall of the temporal horn and atrium. A portion of the amygdala (outlined in green) has been preserved. The blue lines outline the triangular area between Meyer’s loop and the optic tract with the apex at the lateral geniculate body, through which the temporal horn can be entered through the floor of the sylvian fissure without damaging the optic radiations or optic tract. D, Lateral view of a dissection of the optic radiations. The optic radiations extend forward to the tip of the temporal horn, which is behind the posterior edge of the limen insula. An incision directed straight downward through the inferior circular sulcus more than 1 cm behind the limen insula will cross the optic radiations. E, Enlarged view of the region of the limen, Meyer’s loop, tip of the temporal horn, and the pole of the temporal lobe. (Images courtesy of AL Rhoton, Jr.)