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Vestigial hippocampal sulcus

The vestigial hippocampal sulcus is a small, shallow groove found along the medial aspect of the temporal lobe, demarcating the boundary between the dentate gyrus and the subiculum of the hippocampus. In adults, it is often only visible as a faint indentation, representing a remnant of embryological development. While typically inconspicuous and without direct clinical impact, awareness of its anatomy and appearance on neuroimaging is important for differentiating normal variants from pathologies involving the hippocampal formation.

Synonyms

  • Hippocampal fissure

  • Fissura hippocampi

  • Hippocampal sulcus (when referring to its vestigial form)

Arterial Supply

  • Primarily supplied by branches of the anterior choroidal artery (a branch of the internal carotid artery).

  • Additional supply from posterior cerebral artery branches, particularly the posterior choroidal arteries.

Venous Drainage

  • Drains into the internal cerebral vein.

  • Contributes to the venous outflow of the hippocampal formation via the basal vein of Rosenthal.

Function

  • The vestigial hippocampal sulcus itself does not have a direct function; it is a developmental remnant.

  • It serves as an anatomical landmark to distinguish the dentate gyrus from the subiculum and hippocampal proper during brain development and on imaging.

MRI Appearance

  • T2-weighted images:

    • The vestigial hippocampal sulcus appears as a small, linear, hyperintense (bright) cleft, best seen along the medial aspect of the hippocampal head or body.

    • May be seen as a “dot” or short line on coronal sections.

  • T1-weighted images:

    • Appears as a subtle hypointense (dark) line between the dentate gyrus and subiculum.

    • Often less conspicuous than on T2.

  • FLAIR:

    • Similar to T2, may show a small, linear hyperintensity.

    • Helps distinguish normal sulcus from abnormal signal changes associated with pathology (e.g., hippocampal sclerosis).

CT Appearance

  • Generally not visible on routine CT scans due to limited soft tissue contrast.

MRI images

Vestigial hippocampal sulcus mri 3t coronal image

MRI images

Vestigial hippocampal sulcus mri 3t sagittal image