Physiologic Anatomy of the Cerebral Cortex The functional part of the cerebral cortex is a thin layer of neurons covering the surface of all the
convolutions of the cerebrum. This layer is only 2 to 5 millimeters thick, with a total area of about one
quarter of a square meter. The total cerebral cortex contains about 100 billion neurons. Figure 57-1
shows the typical histological structure of the neuronal surface of the cerebral cortex, with its
successive layers of different types of neurons. Most of the neurons are of three types: (1) granular (also called stellate), (2) fusiform, and (3) pyramidal, the last named for their characteristic pyramidal
shape.
Anatomical and Functional Relations of the Cerebral Cortex to the Thalamus and
