The Sylvian fissure, also known as the lateral sulcus or fissure, separates the frontal and parietal lobes superiorly from the temporal lobe inferiorly. The insular cortex is located immediately deep to the Sylvian fissure.
Anteriorly the fissure courses medially to form the 'stem' of the lateral fissure, also known as the Sylvian cistern, into which passes the middle cerebral artery and its major branches. Laterally, it has two branches or 'rami' which extend into, and divide, the frontal operculum.
The anterior ramus (also known as horizontal ramus) separates the pars orbitalis from the pars triangularis, and the ascending ramus (also known as vertical ramus or anterior ascending ramus) separates the pars triangularis from the pars opercularis.
Superiorly the lateral sulcus may be termed the circular sulcus, surrounding the insular cortex medially.
History and etymology
The Sylvian fissure is named for Franciscus Sylvius (1614-1672), German/Dutch physician and anatomist, who described it as the "fissura cerebri lateralis Sylvii" .