Glossary
Ventricular System
What is the ventricular system?
The ventricular system is a set of connected, fluid-filled cavities in the brain, continuous with the spinal cord's central canal. Its four main ventricles contain cerebrospinal fluid (CSF).
Anatomy
Lateral ventricles
One lateral ventricle lies in each cerebral hemisphere. Its parts include frontal, occipital, and temporal horns and a body. Choroid plexus tissue within the ventricles secretes CSF.
Third ventricle
The third ventricle lies at the midline between the thalami. The interventricular foramina, or foramina of Monro, connect it with the lateral ventricles.
Fourth ventricle
The fourth ventricle lies between the brainstem and cerebellum. The cerebral aqueduct connects it with the third ventricle. Median and lateral apertures connect it with the subarachnoid space around the brain and spinal cord.
Functions of cerebrospinal fluid
CSF provides cushioning and buoyancy, contributes to the chemical environment around neural tissue, and participates in waste clearance. Fluid movement and drainage involve several routes whose relative roles are still studied.
Hydrocephalus
Hydrocephalus involves abnormal CSF accumulation and ventricular enlargement, often with raised pressure. Problems with flow or absorption can contribute. Ventricular enlargement alone does not establish the diagnosis.
Normal pressure hydrocephalus
Normal pressure hydrocephalus occurs mainly in older adults and can involve walking difficulty, cognitive changes, and urinary incontinence despite pressure measurements that are not persistently high.
Why it matters
The ventricular system helps explain CSF circulation and disorders of that circulation. Keep the cavities, the fluid-producing tissue, and the clinical effects distinct.