sulcus

https://doi.org/10.1351/goldbook.11266
Any long, narrow groove, furrow or shallow depression, specifically referring to one of the fissures on the surface of the brain.
Source:
PAC, 2016, 88, 713. 'Glossary of terms used in developmental and reproductive toxicology (IUPAC Recommendations 2016)' on page 809 (https://doi.org/10.1515/pac-2015-1202)