Ventricles of The Brain

Within the cerebral hemispheres and brain stem are a series of cavities called "ventricles." These spaces are contiguous with the central canal of the spinal cord and, like the spinal cord, they are filled with cerebrospinal fluid. The largest of the ventricles are the first and second (lateral) ventricles, which extend into the cerebral hemispheres and occupy portions of the frontal, temporal, and occipital lobes. The third ventricle is in a narrow space in the midline of the brain and connects with the lateral ventricles through openings in the front of it, which are called "interventricular foramina." The fourth ventricle is located in the brain stem, just in front of the cerebellum. It is connected to the third ventricle by a narrow canal, the "cerebral aqueduct" (aqueduct of Sylvius), which passes lengthwise through the brain stem. This ventricle is contiguous with the central canal of the spinal cord and has openings in its roof that lead into the meninges (membranes that cover the brain and spinal cord).