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Topic

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Posterior hippocampal artery

The posterior hippocampal artery is a branch of the posterior cerebral artery (PCA) that supplies the posterior portion of the hippocampus and adjacent parahippocampal structures. It usually arises from the P2 or P3 segment of the PCA and courses along the medial temporal lobe toward the hippocampal formation. This artery plays a vital role in maintaining hippocampal perfusion, especially for the posterior hippocampus, dentate gyrus, and parahippocampal gyrus, which are essential for memory processing and spatial navigation.

The posterior hippocampal artery is part of a vascular network that includes the anterior hippocampal artery and collateral contributions from the anterior choroidal artery, providing a redundant blood supply to this memory-critical region. Its precise anatomy can vary, with some individuals having a single dominant vessel, while others demonstrate multiple smaller branches.

Function

  • Supplies the posterior hippocampus and adjacent parahippocampal gyrus

  • Contributes to perfusion of the dentate gyrus and hippocampal circuits essential for memory

  • Provides vascular redundancy along with the anterior hippocampal artery

  • Supports limbic system function, including learning and spatial orientation

Synonyms

  • PCA hippocampal branch

  • Hippocampal posterior branch

  • Posterior branch of hippocampal artery

MRI Appearance (MR Angiography)
T1-weighted images:

  • The artery itself appears as a flow void (signal void) within the temporal lobe region.

  • Adjacent hippocampal structures are isointense to gray matter.

T2-weighted images:

  • Vessel lumen demonstrates signal void, while surrounding parenchyma appears intermediate to hyperintense depending on tissue type.

  • May indirectly show ischemic changes if the artery is occluded (posterior hippocampal infarct).

T1 Post-Contrast (Gadolinium-enhanced MRA):

  • The posterior hippocampal artery enhances as part of the posterior cerebral artery branches.

  • Contrast helps delineate small-caliber vessels and assess for stenosis or occlusion.

CT Appearance (CTA):

  • On CT angiography, the posterior hippocampal artery appears as a fine contrast-filled branch extending from the PCA toward the posterior hippocampus.

  • Best visualized with thin-section CTA reconstructions in coronal and sagittal planes.

  • CT can demonstrate occlusion, stenosis, aneurysm, or vessel caliber abnormalities.

  • Non-contrast CT may only show indirect signs of infarction in the hippocampal territory, such as hypodensity in the posterior hippocampus.

MRI images

Posterior hippocampal artery