00:00Welcome to 2-Minute Neuroscience, where I simplistically explain neuroscience topics in 2 minutes or less.
00:04In this installment, I will discuss the ventricles.
00:08The ventricles are a network of cavities that are distributed throughout the brain.
00:12They are aligned with a specialized membrane called the choroid plexus,
00:15which is composed of glial cells called ependymal cells.
00:18Ependymal cells are specially designed to secrete cerebrospinal fluid,
00:21which then flows through the ventricles and around the brain.
00:24Thus, the main role of the ventricles is the production and distribution of cerebrospinal fluid.
00:29Cerebrospinal fluid, or CSF as it is commonly called,
00:32is a clear, colorless liquid that performs a number of important functions in the brain.
00:36Among other things, CSF surrounds the brain, forming a protective layer and suspending the brain in fluid,
00:41which reduces the strain forces like gravity would have on the brain.
00:44Also, it constantly flows through and around the brain,
00:46removing toxins and regulating the extracellular environment of neurons.
00:50There are four ventricles.
00:52There are two C-shaped lateral ventricles, one in each of the cerebral hemispheres.
00:56The lateral ventricles are connected to a third ventricle by an opening called the interventricular foramen.
01:02The third ventricle is a narrow cavity that runs along the midline of the diencephalon.
01:07It looks something like a misshapen donut,
01:09and the section that would be the hole of the donut is an area known as the interthalamic adhesion.
01:13In this section, the thalamus makes up the wall of the third ventricle.
01:17The third ventricle communicates with the fourth ventricle via the cerebral aqueduct.
01:21The fourth ventricle is wedged between the cerebellum on one side and the brain stem on the other.
01:26The fourth ventricle is shaped like a tent whose peak protrudes into the cerebellum.
01:30There are three openings in the fourth ventricle that allow cerebrospinal fluid to enter the subarachnoid space,
01:35a CSF-containing cavity that surrounds the brain.
01:38Thus, CSF leaves the ventricular system via the fourth ventricle.
01:41The fourth ventricle extends to and is continuous with the central canal,
01:44a CSF-filled cavity that runs the length of the spinal cord.
01:47If CSF circulation is blocked as by a tumor or is otherwise abnormally excessive,
01:52it can result in increased pressure and expansion of the ventricles.
01:55This creates a condition known as hydrocephalus,
01:58which can cause a variety of complications and be life-threatening.
