The area postrema is separated from the vagal trigone by the funiculus separans, a thin semitransparent ridge. The vagal trigone overlies the dorsal vagal nucleus and is situated on the caudal end of the rhomboid fossa or 'floor' of the fourth ventricle.
The area postrema is demarcated from the vagal trigone by the funiculus separans, a thin semitransparent ridge. The vagal trigone sits atop the dorsal vagal nucleus and is positioned at the tail end of the rhomboid fossa or 'floor' of the fourth ventricle.