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Topic

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Calcarine Sulcus

The calcarine sulcus is a prominent anatomical landmark located on the medial surface of the occipital lobe of the brain. It plays a crucial role in forming the primary visual cortex (Brodmann area 17), which is responsible for processing visual information received from the eyes. The sulcus begins near the parieto-occipital sulcus and runs horizontally toward the occipital pole, dividing the cuneus above from the lingual gyrus below. Its precise identification is essential in neuroimaging and neurosurgical procedures due to its association with visual function.

Synonyms

  • Calcarine fissure

  • Sulcus calcarinus

Function

  • Serves as the anatomical landmark for the primary visual cortex (V1, Brodmann area 17).

  • Essential for the initial cortical processing of visual input from the contralateral visual field.

  • Involved in conscious visual perception.

Arterial Supply

  • Posterior cerebral artery (PCA):

    • Specifically, the calcarine branch of the PCA provides the main arterial supply.

  • Additional minor contributions may come from the parieto-occipital artery (also a branch of PCA).

Venous Drainage

  • Drained primarily by the calcarine vein.

  • The calcarine vein empties into the superior sagittal sinus and/or straight sinus via the vein of Galen.

MRI Appearance

  • T1-Weighted Images:

    • The calcarine sulcus appears as a hypointense (dark) line/groove, separating the medial occipital cortex into the cuneus (superiorly) and lingual gyrus (inferiorly).

    • The cortex itself is isointense to other cortical gray matter.

  • T2-Weighted Images:

    • The sulcus appears hyperintense (bright) due to the presence of cerebrospinal fluid (CSF) within the groove.

    • Surrounding cortical structures maintain typical T2 signal characteristics.

  • FLAIR (Fluid-Attenuated Inversion Recovery):

    • The calcarine sulcus is well visualized as a CSF-filled space, which appears hypointense (dark) because CSF is suppressed.

    • Enhances delineation of the surrounding cortex for detecting lesions or pathology.

CT Appearance

  • Appears as a linear hypodense (dark) groove on the medial aspect of the occipital lobe.

  • More easily seen in cross-sectional slices through the occipital lobe.

  • Best visualized on thin, high-resolution axial or sagittal reconstructions.

MRI images

Calcarine sulcus MRI 3T axial image

MRI images

Calcarine sulcus MRI 3T sagittal image