Dictionary.net

• In the posterior part of the anterior half of the floor of the fourth ventricle, in the median line.

1898 - American pocket medical dictionary
By Willam Alexander Newman Dorland

• An area in the median line of the anterior half of the floor of the fourth ventricle. C. Bernard discovered that a puncture in this region caused glycosuria.

1916 - Appleton's medical dictionary
By Smith Ely Jelliffe