Welcome to 2 minute neuroscience, where I simplistically explain neuroscience topics
in 2 minutes or less.
In this installment I will discuss the ventricles.
The ventricles are a network of cavities that are distributed throughout the brain.
They are lined with a specialized membrane called the choroid plexus, which is composed
of glial cells called ependymal cells.
Ependymal cells are specially designed to secrete cerebrospinal fluid, which then flows
through the ventricles and around the brain.
Thus the main role of the ventricles is the production and distribution of cerebrospinal
Cerebrospinal fluid, or CSF as it is commonly called, is a clear colorless liquid that performs
a number of important functions in the brain.
Among other things, CSF surrounds the brain, forming a protective layer and suspending
the brain in fluid, which reduces the strain forces like gravity would have on the brain.
Also, it constantly flows through and around the brain removing toxins and regulating the
extracellular environment of neurons.
There are 4 ventricles.
There are two C-shaped lateral ventricles, one in each of the cerebral hemispheres.
The lateral ventricles are connected to a third ventricle by an opening called the interventricular
The third ventricle is a narrow cavity that runs along the midline of the diencephalon.
It looks something like a misshapen donut, and the section that would be the hole of
the donut is an area known as the interthalamic adhesion.
In this section the thalamus makes up the wall of the third ventricle.
The third ventricle communicates with the fourth ventricle via the cerebral aqueduct.
The fourth ventricle is wedged between the cerebellum on one side and the brainstem on
The fourth ventricle is shaped like a tent whose peak protrudes into the cerebellum.
There are three openings in the fourth ventricle that allow cerebrospinal fluid to enter the
subarachnoid space, a CSF-containing cavity that surrounds the brain.
Thus, CSF leaves the ventricular system via the 4th ventricle.
The 4th ventricle extends to, and is continuous with, the central canal, a CSF-filled cavity
that runs the length of the spinal cord.
If CSF circulation is blocked as by a tumor, or is otherwise abnormally excessive, it can
result in increased pressure and expansion of the ventricles.
This creates a condition known as hydrocephalus, which can cause a variety of complications
and be life-threatening.