Lateral sulcus

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Structures seen on the lateral view of the brain.

The lateral sulcus, also known as Sylvian fissure, is a very deep fold seen on the lateral surface of the cerebral hemisphere running in an anteroposterior direction.

It is one of the major sulci of the brain and separates the temporal lobe from the frontal and parietal lobes. The insular lobe lies deep to the lateral sulcus.

The lateral sulcus has three branches or rami:

• The first branch, called the anterior ramus, extends forward and passes superiorly into the inferior frontal gyrus, separating its orbital part from the triangular part.
• The second branch, called the ascending ramus, extends upward into the inferior frontal gyrus, separating its triangular part from the opercular part.
• The third branch which is also the longest is called the posterior ramus. It is the primary continuation of the lateral sulcus and separates the parietal and temporal lobes. The posterior ramus ends by meeting the groove of the supramarginal gyrus.