The collateral fissure is a large sulcus on the tentorial surface of the cerebral hemisphere and extends from near the occipital pole to within a short distance of the temporal pole. It is also known as the medial occipitotemporal sulcus.^[1]

Behind, it lies below and lateral to the calcarine fissure, from which it is separated by the lingual gyrus; in front, it is situated between the parahippocampal gyrus and the anterior part of the fusiform gyrus.

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  Coronal section through posterior cornua of lateral ventricle. (Collateral fissure labeled at bottom center.)
• Human brain dissection video (62 sec). Demonstrating location of collateral sulcus.

This article incorporates text in the public domain from page 820 of the 20th edition of Gray's Anatomy (1918)