From the case: Sagittal midline of the brain: normal anatomy
Normal sagittal midline demonstrating the continuity of the CSF flow channels. 1. Intraventricular foramen of Monroe. 2. Posterior floor of the third ventricle formed by the convex superior border of the midbrain. 3. Cerebral aqueduct of Sylvius. 4. Median aperture of Magendie.