Sulcus

Sulcus (plural sulci) is a term used in anatomy to describe a groove, furrow, or depression on the surface of an organ, tissue, or bone. The word derives from the Latin “sulcus,” meaning “furrow.” Sulci are most commonly associated with the brain, where they separate the raised ridges known as gyri, thereby increasing the cortical surface area within the limited volume of the skull. In the cerebral cortex, major sulci such as the central, lateral, and Sylvian fissures serve as anatomical landmarks for clinicians and neurosurgeons.

Beyond the central nervous system, sulci occur in other structures. The heart possesses the coronary sulcus, a groove encircling the organ that houses the coronary vessels and demarcates the atria from the ventricles. In the kidney, the renal sulcus marks the external indentation separating the renal cortex from the renal medulla. Skeletal anatomy includes the intertubercular sulcus of the humerus, a groove for the long head of the biceps brachii tendon.

Clinically, sulcal patterns can aid in the diagnosis of neurological disorders. Enlarged cortical sulci may indicate cerebral atrophy seen in Alzheimer's disease, whereas shallow or absent sulci can be a feature of developmental brain malformations such as lissencephaly. Imaging modalities like MRI and CT scans rely on sulcal anatomy to orient clinicians and assess pathological changes.

The concept of a sulcus also appears in histology, where microscopic grooves delineate cellular layers or tissue boundaries. Overall, sulci are essential structural features that increase surface area, accommodate vascular and neural pathways, and provide reference points for anatomical study and medical practice.