This article gives descriptions and measurements of the cerebral ventricles, especially our measurements of the interventricular foramen and the third ventricle. Included are measurements of previous and recent research. The results of endoscopic reviews of the lateral, third and fourth ventricles are also discussed. The subarachnoid spaces are described and illustrated by our corrosion casts. During endoscopic inspection of the subarachnoid spaces, the transcisternal veins are extremely vulnerable. Therefore, these veins in the anterior, middle and posterior cranial fossae are described.