Cerebellomedullary Fissure and Nearby Anatomy. E, The tip of a nerve hook has been placed inside the fourth ventricle and is seen through the paper-thin inferior medullary velum. The PICA courses in the cleft between the rostral pole of the tonsil below and the tela choroidea and inferior medullary velum above. F, The left half of the inferior medullary velum has been divided to expose the superolateral recess and the ventricular surface formed by the superior and inferior peduncles. The uvula has been retracted to the right to expose the entire floor and much of the roof of the ventricle. G and H, Views of another specimen showing the relationship between the tela choroidea and the ventricle. G, The right half of the tela choroidea has been removed up to its junction with the inferior medullary velum. The taeniae constitute the site of attachment of the tela along the inferolateral margins of the floor. The vein of the cerebellomedullary fissure crosses the inferior medullary velum on the left side. H, The tela has been removed bilaterally to expose the floor and both lateral recesses. (Images courtesy of AL Rhoton, Jr.)