Sulci

Sulci (singular sulcus) are grooves or furrows on the surface of the brain, specifically the cerebral cortex. Along with the gyri, the raised ridges, sulci create the folded texture of the brain and help increase cortical surface area within the skull. Sulci are generally shallower than fissures, which are deeper grooves that also separate major brain regions.

During fetal development, the cortex undergoes gyrification, producing primary sulci (the first and most prominent), followed by secondary and tertiary sulci. Notable examples include the central sulcus, which separates the frontal and parietal lobes and lies near the primary motor and somatosensory cortices, and the lateral sulcus (Sylvian fissure), which separates the temporal lobe from the frontal and parietal lobes. Other well-known sulci include the parieto-occipital sulcus and the calcarine sulcus in the occipital lobe.

Sulcal patterns vary between individuals and can change with age or pathology. In neuroimaging and neurosurgical planning, sulci serve as important anatomical landmarks for identifying cortical areas associated with motor and sensory functions, language, vision, and higher cognitive processes. The term sulcus derives from Latin sulcus, furrow, and while it most often refers to brain grooves, the word can describe grooves in other anatomical structures as well.