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Lateral sulcus (Sylvian fissure)

The lateral sulcus, also known as the Sylvian fissure, is one of the most prominent anatomical landmarks of the human brain. It separates the frontal and parietal lobes above from the temporal lobe below and extends laterally from the basal surface of the brain. Recognized for its crucial role in dividing major brain regions, the lateral sulcus serves as an important reference point in neuroimaging and neurosurgery. Its development is among the earliest sulci to appear in fetal life, and its appearance and morphology are key indicators in the evaluation of various neurological conditions.

Synonyms

  • Sylvian fissure

  • Fissura lateralis cerebri

  • Lateral cerebral fissure

Function

  • Separates the frontal and parietal lobes (superiorly) from the temporal lobe (inferiorly).

  • Contains important cortical areas related to auditory processing, language (Broca’s and Wernicke’s areas), and sensory integration.

  • Serves as a landmark for neurosurgical procedures and in neuroimaging interpretation.

Arterial Supply

  • Primarily supplied by the middle cerebral artery (MCA), which runs within the lateral sulcus.

  • Branches of the MCA provide blood to the lateral aspects of the frontal, temporal, and parietal lobes bordering the sulcus.

Venous Drainage

  • Drained mainly by the superficial middle cerebral vein (Sylvian vein), running parallel to the artery in the sulcus.

  • Drains into the cavernous sinus or sphenoparietal sinus.

MRI Appearance

  • T2-weighted: Appears as a linear hyperintense (bright) cerebrospinal fluid (CSF)-filled space separating the lobes; margins are well-demarcated.

  • T1-weighted: Appears as a hypointense (dark) CSF-filled fissure; gray and white matter of adjacent gyri are visualized on either side.

  • FLAIR: The sulcus itself is typically dark due to suppression of CSF signal, highlighting any abnormal signal in the adjacent cortex or subarachnoid space.

CT Appearance

  • Appears as a linear hypodense (dark) space due to the presence of CSF, separating the brain lobes.

  • The fissure can be accentuated in cases of atrophy, edema, or subarachnoid hemorrhage (hyperdense blood may be seen outlining the sulcus in acute bleed).

MRI images

Lateral sulcus (Sylvian fissure) MRI 3T axial image

MRI images

Lateral sulcus (Sylvian fissure) MRI 3T sagittal image

CT image

Lateral sulcus (Sylvian fissure) CT IMAGE