Median aperture

Overview
The median aperture of the brain (or foramen of Magendie) is an opening in the hollow nerve tube, connecting the fourth ventricle of the brain with the subarachnoid space.

The median aperture, along with the two lateral apertures (foramina of Luschka), one on the left and one on the right, are the three primary routes for cerebrospinal fluid to escape into the cisterna magna.

Eponym
The Foramen of Magendie is named for François Magendie, who first described it.