The mammillary bodies also mamillary bodies, are a pair of small round brainstem nuclei. They are located on the undersurface of the brain that, as part of the diencephalon, form part of the limbic system. They are located at the ends of the anterior arches of the fornix. They consist of two groups of nuclei, the medial mammillary nuclei and the lateral mammillary nuclei.
Neuroanatomists have often categorized the mammillary bodies as part of the posterior part of hypothalamus.
Structure
Connections
They are connected to other parts of the brain (as shown in the schematic, below left), and act as a relay for impulses coming from the amygdalae and hippocampi, via the mamillothalamic tract to the thalamus.
The lateral mammillary nucleus has bidirectional connections with the dorsal tegmental nucleus. The medial mammillary nucleus connects with the ventral tegmental nucleus.
Function
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File:Slide5dd.JPG|Mammillary body
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Mammillary bodies, and their projections to the anterior thalamus via the mammillothalamic tract, are important for recollective memory. According to studies of rats with mammillary body lesions, damage to the medial mammillary nucleus lead to spatial memory deficits.
Mammillary body atrophy is present in several other conditions, such as colloid cysts in the third ventricle, Alzheimer's disease, schizophrenia, heart failure, and sleep apnea. In spite of this the exact function of the mammillary bodies is still not clear.