Neuroanatomy, Cerebral Cortex

The cerebral cortex is composed of a complex association of tightly packed neurons covering the outermost portion of the brain. It is the gray matter of the brain. Lying right under the meninges, the cerebral cortex divides into four lobes: frontal, temporal, parietal and occipital lobes, each with a multitude of functions. It is characteristically known for its bulges of brain tissue known as gyri, alternating with deep fissures known as sulci. The enfolding of the brain is an adaptation to the dramatic growth in brain size during evolution. The various folding of brain tissue allowed large brains to fit in relatively small cranial vaults that had to remain small to accommodate the birth process. Notable sulci include the Sylvian fissure which divides the temporal lobe from the frontal and parietal lobe, the central sulcus which separates the frontal and parietal lobes, the parieto-occipital sulcus which divides the parietal and occipital lobes, and the calcarine sulcus which divides the cuneus from the lingual gyrus. The cerebral cortex contains sensory, motor and important association areas. The thalamus receives somatosensory information and conveys it to the primary somatosensory cortex in the postcentral gyrus of the parietal lobe. Other important primary cortical sensory areas include the temporal lobe auditory cortex and the occipital lobe visual cortex. Each sensory area has associated sensations given specific stimuli, providing meaning to sensations. The motor regions of the cerebral cortex are located predominantly in the frontal lobe, anterior to the central sulcus, and include the primary motor cortex (found in the precentral gyrus) and the premotor cortex, which initiates and regulates voluntary movement.