gyrus

A gyrus, plural gyri, is a ridge on the surface of the cerebral cortex. Gyri are separated by sulci, the grooves that form the folds of the brain. The folding increases the cortical surface area, allowing a greater density of neurons within the limited volume of the skull and supporting higher cognitive and motor functions.

Many gyri are named for their location. The precentral gyrus lies in front of the central sulcus and contains the primary motor cortex. The postcentral gyrus lies behind the central sulcus and contains the primary somatosensory cortex. The frontal lobes contain the superior, middle, and inferior frontal gyri, with the inferior frontal gyrus including language-related regions in the dominant hemisphere. The superior temporal gyrus is involved in auditory processing, and its posterior portion on the left is commonly associated with language comprehension.

Other notable gyri include the cingulate gyrus along the medial surface of the cortex, the parahippocampal gyrus adjacent to the hippocampus, and the fusiform and lingual gyri in the occipitotemporal region that participate in memory and visual processing. Developmentally, gyri form through cortical folding, a process called gyrification. Humans have highly gyrified (gyrencephalic) brains compared with smoother-brained species. Normal individual variation in gyral patterns is common, while atypical patterns can be associated with certain developmental conditions.