Inferior Perspective of Telovelar Approach. The right cerebellar tonsil has been retracted to permit visualization of the inferior aspect of the fourth ventricle. The segments of the posterior inferior cerebellar artery are observed within this region bilaterally. This perspective demonstrates how gentle lateral retraction of the cerebellar tonsils is necessary to successfully expose the tela choroidea and inferior medullary velum in this surgical approach. (Image courtesy of AL Rhoton, Jr.)