In spite of the common connotations of the word "ventricles," the lateral ventricles are not located in the heart, but in the brain. The brain is largely made up of dense collections of nerve tissue, and the brain's ventricular system is connected to the central canal of the spinal cord and helps circulate necessary cerebrospinal fluid throughout the brain. This fluid serves to protect the brain, and it allows the brain to "float" within the skull, thus reducing its relative weight.
The lateral ventricles are located within the brain, with one ventricle located in each hemisphere. They are roughly horseshoe shaped, with a central region as well as anterior, or frontal, posterior, or rear, and inferior, or temporal, horns. This curved shape causes the lateral ventricles to pass through all four lobes of the brain — the frontal, temporal, parietal and occipital.
Lateral ventricles are the highest portion of the brain's ventricular system, and are the largest of the ventricles. Above the anterior horns of each lateral ventricle are the corpus callosum, the dense mass of nerve tissue that connects the brain's right and left sides and makes it possible for them to communicate. In the back of the brain, the posterior horns pass through the occipital lobe. The temporal horns pass through the temporal lobes, which are located behind the temples.
At the interventricular foramina, the lateral ventricles connect to the third ventricle. From the third ventricle, the system continues into the fourth ventricle, which is the lowest ventricle in the system. The fourth ventricle then connects to the spinal cord, completing the system.
Cerebrospinal fluid, which is circulated through the lateral ventricles and the rest of the ventricular system, performs several important functions. It increases the buoyancy of the brain so that lower portions of the brain are not crushed by the organ's overall weight, and it helps maintain the proper pressure within the skull. It also protects the brain from injury when the head is jolted or struck. In addition, cerebrospinal fluid helps bring nutrients to the brain, remove wastes and helps maintain proper chemical balances.
Of the four ventricles, the lateral ventricles are most the likely to experience meningiomas, which are tumors that occur in the nervous system. These tumors usually are benign, but in rare cases, they can be malignant. Meningiomas often produce no symptoms at all. If they do cause problems, such as impaired vision or intercranial pressure, they usually can be surgically removed.