Ventricles of the Brain

There are all together four ventricles in the human brain that constitute the ventricular system. The ventricular system can be defined as the structure that contains the cerebrospinal fluid in the brain. The entire system consists of four ventricles, which are known as lateral ventricles, third ventricle and fourth ventricle. There are two lateral ventricles in the brain, the right and the left ventricles, which are located within the cerebrum. The lateral ventricles of the brain are comparatively larger than the other ventricles and are C-shaped.

Understanding the Ventricular System

As we know, there are four ventricles in the human brain. All these four ventricles develop from the central canal of the neural tube. It is during the first trimester of pregnancy, when the ventricles develop from the central canal. All the ventricles, the lateral, the third and the fourth ventricle are adjoined to one another, and continue with the central canal of the spinal cord. The right and the left lateral ventricles are located in cerebrum, beneath the corpus collosum, while the third ventricle is located between the thalami in the diencephalon. The fourth ventricle on the other hand, can be found between the cerebellum and the pons.

The two lateral ventricles connect to the third ventricle through the intraventricular foramen, which is a narrow, oval-shaped opening. The mesencephalic aqueduct lies adjacent to the third and the fourth ventricles. The third ventricle communicates with the fourth ventricle via the cerebral aqueduct. Each of the lateral ventricles has three horns, the anterior or the frontal horn, the posterior or the occipital horn and the inferior or the temporal horn. The inside of the lateral ventricles remain covered with ependyma, which consists of epithelial cells.

They contain cerebrospinal fluid (CSF). The structure concerned with the production of cerebrospinal fluid is called choroid plexus, which can be found in the lateral, third and the fourth ventricle of the brain. This structure contains the modified ependymal cells, which produce cerebrospinal fluid. CSF flows from the lateral ventricles to the third ventricles through the foramina of Monro or intraventricular foramen. Then CSF flows into the fourth ventricle through the cerebral aqueduct and from there, it enters the central canal of the spinal cord or the cisterns of the subarachnoid space through the foramen of Magendie and the foramina or Luchka. Ultimately, CSF flows around the superior sagittal sinus, where it is absorbed by the bloodstream through the structures, called arachnoid villi. The arachnoid villi act as one way valves, which allows the CSF to pass into the bloodstream, when pressure of CSF greater than the venous pressure. But, they do not allow the blood to flow into the ventricular system, when the venous pressure is greater than CSF pressure.

Ventricle Functions

In the brain, their function is the protection of the brain by providing cushioning. The cerebrospinal fluid produced in the ventricles act as the cushion to minimize the impact of any kind of trauma to the head. Again, CSF travels through the ventricles, or the ventricular system provides a pathway for the effective circulation of CSF, so that it can provide protection to the brain. CSF is concerned with the excretion of waste products such as, harmful metabolites or drugs from the brain, besides transporting the hormones to various part of the brain. It also provides buoyancy to the brain, which in turn, helps to reduce the weight of the brain. Just because our brain remains immersed in cerebrospinal fluid, its weight reduces from 1,400 gm to almost 50 gm, which in turn, reduces pressure at the base of the brain.

Several diseases can affect the ventricular system of the brain, out of which hydrocephalus, meningitis or ventriculitis are worth mentioning. Hydrocephalus generally occurs when the production of CSF is larger than its absorption, or when its flow through the foramina or aqueduct is blocked. This increases pressure in the ventricles and cause hydrocephalus, which is also known as water in the brain. On the other hand, meningitis or ventriculitis can be caused by infection. The CT scan of the ventricles on the other hand, can provide useful insight into the study of various mental disorders. Some scientific researches found that the ventricles of schizophrenic patients are larger than healthy individuals. However, it is still not clear whether mental disorders cause the enlargement of ventricles, or enlargement of ventricles causes mental disorders. Nevertheless, they are one of the most important parts for the smooth operation of the brain functions.