Vagal triangle (Trigonum vagi or ala cineria), is a triangular dark area bounded laterally by the vestibular area, medially by the hypoglossal triangle and above by the inferior fovea. It overlies the nuclei of glossopharyngeal, vagus and cranial accessory nerves.

Fourth ventricle floor: fc: facial colliculus; ht: hypoglossal triangle; if: inferior fovea; me: medial eminence; ms: median sulcus; o: obex; sf: superior fovea; sl: sulcus limitans; sm: medullary striae of fourth ventricle; vt: vagal triangle.