The lateral sulcus, or Sylvian fissure, is the deep groove on the side of each cerebral hemisphere that divides the frontal and parietal lobes above from the temporal lobe below. The insula lies hidden deep within it. [1][2]
The 3D brain needs JavaScript. The text below still says where the lateral sulcus is and what it does.
Seen from the left: the frontal and parietal lobes are lit in blue, the temporal lobe in orange, on both hemispheres. The groove runs where blue meets orange; the front (coronal) slice button cuts across it. Drag to turn, pinch or scroll to zoom, tap any part to name it; .
A groove has no shape of its own; lit: the parts on either side of it. Lit: above, the frontal and parietal lobes in blue; below, the temporal lobe in orange. It divides the frontal and parietal lobes above from the temporal lobe below; the insula, not lit here, lies deep within it. [1][2]
Where it is
It divides both the frontal lobe and the parietal lobe above from the temporal lobe below; it is the landmark that separates the temporal lobe from the other regions. [1][3]
The insula, a fold of cortex, lies deep within the lateral sulcus; parts of the frontal, temporal and parietal lobes cover it like lids, the opercula. [2][1]
Near its front end two short branches, the ascending (vertical) ramus and the horizontal ramus, cut into the inferior frontal gyrus. [1]
Above it, the central sulcus runs down the side of the hemisphere towards it, between the frontal and parietal lobes. [4][3]
It is often longer and less curved on the left hemisphere than on the right, a difference Wikipedia ties to the Yakovlevian torque. [1]
It is one of the earliest grooves to form in the human brain, appearing around the fourteenth week of gestation. [1]
What it does
It holds the transverse temporal gyri, which are part of the primary auditory cortex, on its hidden floor. [1]
The secondary somatosensory cortex lies in the parietal operculum, on the ceiling of the lateral sulcus. [1]
Inside it
In the human brain about two-thirds of the folded cortex is buried within sulci; the insula is the largest example, a whole region of cortex hidden inside this one groove. [5][2]
Other names
Also called the lateral fissure or the Sylvian fissure, after Franciscus Sylvius, a professor of medicine at Leiden University; the 1641 description credited to him may not have been his. [1]
Sulcus or fissure: a sulcus is the groove between two gyri, and deeper furrows that divide the brain into lobes are often called fissures, which is why this groove has both names. [5][3]
Size
The model has no shape for the lateral sulcus, so the groove itself is not measured here. On the left hemisphere, the stretch where the frontal and parietal lobes and the temporal lobe come within 3 mm of each other fits in a box about 116 mm front to back, 38 mm top to bottom and 45 mm side to side (the box that stretch fits in, not the groove’s length along its bends or its depth). [6]
Facts describe anatomy and normal function only. The 3D model is the adult male BodyParts3D brain (credits and licence); real brains vary in size and shape, so its measurements describe one model, not anyone’s brain.