The folds or ridges that dominate the exterior view are called gyri (singular: gyrus). The gyri are separated from one another by indentations or grooves called sulci (singular: sulcus) when they are relatively shallow, and called fissures (singular: fissure) when they are deeper.
There is a longitudinal fissure that divides the cerebrum into two hemispheres, the left hemisphere on the anatomical left, and the right hemisphere on the anatomical right. The longitudinal fissure is deep, but the two hemispheres are eventually connected to each other at the base of the longitudinal fissure by a thick wide structure called the corpus callosum. See Figure 10-4.
The various sulci and fissures in the cerebrum divide each hemisphere in four lobes, the frontal lobe, the parietal lobe, the occipital lobe, and the temporal lobe. Notice that each lobe has the same name as the cranial bone that is directly over it. See Figure 10-5.
There are a number of fluid-filled cavities in the cerebrum. The cavities are called the ventricles. The cells that line the ventricles produce the cerebrospinal fluid, which is the fluid contained within them. The cerebrospinal fluid is not confined to the ventricles. It surrounds the entire brain and the entire spinal cord.