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Topic

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Mammillary body

The mammillary bodies are paired, small, round structures located on the undersurface of the brain, forming part of the diencephalon and situated at the ends of the anterior arches of the fornix. These nuclei are an integral part of the limbic system, playing a significant role in memory circuits and acting as a relay between the hippocampus and thalamus. The mammillary bodies are clinically important due to their involvement in memory processing and their susceptibility to pathological changes in various neurological conditions.

Synonyms

  • Corpora mammillaria

  • Mammillary tubercles

  • Mammillary nuclei

Function

  • Relay nuclei in the limbic system, especially in the Papez circuit

  • Major role in recollective and spatial memory

  • Receives input from the hippocampus via the fornix

  • Sends projections to the anterior nucleus of the thalamus through the mammillothalamic tract

  • Involved in recognition memory and emotional responses

Arterial Supply

  • Supplied primarily by branches of the posterior cerebral artery (PCA), especially the posteromedial branches

  • Additional supply from branches of the posterior communicating artery

Venous Drainage

  • Drained by the small veins into the basal veins of Rosenthal

  • Ultimately drain into the great cerebral vein (vein of Galen)

MRI Appearance

  • T1-weighted images:

    • Mammillary bodies appear as small, round, isointense to slightly hypointense structures relative to adjacent gray matter

    • Clearly delineated from the surrounding CSF and hypothalamic tissue

  • T2-weighted images:

    • Mammillary bodies are  isointense relative to adjacent brain tissue

    • Well visualized against the background of the hypothalamus and third ventricle

  • FLAIR (Fluid Attenuated Inversion Recovery):

    • Mammillary bodies typically show similar signal intensity to surrounding gray matter

    • Pathological conditions (e.g., Wernicke’s encephalopathy) may cause hyperintensity

CT Appearance

  • Mammillary bodies are not well visualized on non-contrast CT due to their small size and similar density to adjacent structures

  • They may be seen as subtle round structures at the base of the brain, anterior to the interpeduncular fossa

MRI images

Mammillary body mri 3t axial image

MRI images

Mammillary body mri 3t coronal image

MRI images

Mammillary body mri 3t sagittal image