What are the ventricles?

• A. Two lateral ventricles, third ventricle, and fourth ventricle
• B. The brainstem
• C. The cerebellum
• D. The thalamus

Answer: (A)

Ventricles are the CSF-filled cavities that make up the brain’s ventricular system. It includes two lateral ventricles in the cerebral hemispheres, the third ventricle in the diencephalon, and the fourth ventricle between the brainstem and cerebellum. Cerebrospinal fluid is produced mainly by the choroid plexuses and flows from the lateral ventricles through the foramina of Monro into the third ventricle, then through the cerebral aqueduct into the fourth ventricle, and onward into the subarachnoid space where it’s reabsorbed. This system cushions the brain, provides nutrients, and helps remove waste. The brainstem, cerebellum, and thalamus are solid brain structures, not cavities, so they are not ventricles.