Ventricles

01What is

Four interconnected cavities, deep inside the brain, that produce and circulate cerebrospinal fluid.

02Anatomy

The ventricular system comprises two lateral ventricles (one per hemisphere), the midline third ventricle in the diencephalon, and the fourth ventricle dorsal to the brainstem. They communicate via the interventricular foramina of Monro and the cerebral aqueduct of Sylvius.

03Function

The choroid plexus lining each ventricle secretes cerebrospinal fluid (CSF) at roughly 500 ml per day. CSF cushions the brain, removes metabolic waste, and — through the recently characterised glymphatic system — clears amyloid and other proteins during sleep.

04Clinical significance

Obstruction of CSF flow produces hydrocephalus. Ventriculomegaly is a marker of tissue loss in schizophrenia, Alzheimer's, and normal-pressure hydrocephalus. The ventricles are also a common landmark and surgical corridor in neuroimaging and neurosurgery.

Further reading

1. [1]
   Iliff, J. J. et al. (2012). A paravascular pathway facilitating CSF flow Sci. Transl. Med. 4(147).
2. [2]
   Sakka, L. et al. (2011). Anatomy and physiology of cerebrospinal fluid Eur. Ann. Otorhinolaryngol..