Floor of the Fourth Ventricle

**Semantic type:** Anatomical Structure

**Definition:** The lower or ventral portion of the fourth ventricle transversed by the median sulcus with numerous nuclei and structures including the striae acusticae (or medullaris), fovea inferior and fovea superior, clava, obex, area postrema, and the trigonum hypoglossi and trigonum vagi.