Topics

Topic

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Body of hippocampus

The body of the hippocampus is the middle portion of the hippocampal formation, extending between the head (anterior) and tail (posterior) of the hippocampus within the medial temporal lobe. It lies in the floor of the temporal horn of the lateral ventricle, bordered superiorly by the choroid fissure and fornix, and inferiorly by the parahippocampal gyrus. Structurally, it is composed of the dentate gyrus, cornu ammonis (CA1–CA4), and subiculum. The hippocampal body plays a crucial role in memory consolidation, spatial navigation, and emotional regulation, and is highly vulnerable to hypoxia, ischemia, epilepsy, and neurodegenerative disease.

Synonyms

  • Hippocampal body

  • Mid-hippocampus

  • Middle hippocampal segment

Function

  • Consolidates short-term memory into long-term memory

  • Involved in spatial orientation and navigation

  • Integrates sensory and emotional information with the limbic system

  • Plays a role in learning and cognition

  • Highly relevant in epileptogenesis and neurodegeneration (e.g., Alzheimer’s disease)

MRI Appearance

T1-weighted images:

  • Appears as a curved gray-matter structure of intermediate signal intensity in the medial temporal lobe

  • Surrounded by CSF in the temporal horn (low signal), providing contrast

  • Atrophy manifests as volume loss and enlarged temporal horn

T2-weighted images:

  • Hippocampal body demonstrates intermediate signal compared to cortical gray matter

  • CSF in the temporal horn is bright hyperintense, outlining the hippocampus

  • Pathology such as hippocampal sclerosis appears as volume loss and T2 hyperintensity

MRA (Magnetic Resonance Angiography):

  • Not used for direct hippocampal evaluation, but depicts adjacent vessels (posterior cerebral artery branches and anterior choroidal artery) supplying the hippocampus

  • Helpful in ischemic or vascular pathology

T1 Post-Contrast (Gadolinium-enhanced MRI):

  • Normal hippocampal body shows no significant enhancement

  • Pathological states such as inflammation, tumor, or infection may demonstrate focal or diffuse enhancement

  • Contrast MRI helps detect autoimmune encephalitis, hippocampal tumors, or vascular malformations

CT Appearance

  • On non-contrast CT, the hippocampal body appears as a gray matter density structure in the medial temporal lobe, less distinct than on MRI

  • Atrophy may be inferred from temporal horn dilation

  • CT is limited for fine hippocampal anatomy but useful for detecting hemorrhage, calcification, or mass effect

  • CTA can evaluate adjacent vascular supply if ischemia is suspected

MRI images

Body of hippocampus