Mamillary body
Corpus mammillare
One of a pair of small round swellings on the underside of the hypothalamus, a relay of the memory circuit between hippocampus and thalamus.
At a glance
- English
- Mamillary body
- Latin (TA2)
- Corpus mammillare
- System
- Brain and spinal cord
- Region
- Head
- Side
- Paired, left and right
About the mamillary body
The mamillary bodies are two small, pea-sized eminences on the base of the brain, one on each side of the midline. They belong to the posterior part of the hypothalamus. On the inferior surface of the brain they lie in the interpeduncular fossa, behind the tuber cinereum and the stalk of the pituitary gland, and in front of the posterior perforated substance between the cerebral peduncles. Their name refers to their rounded, nipple-like shape.
Each contains a large medial mamillary nucleus and a smaller lateral mamillary nucleus, covered by a capsule of white matter. The main input arrives through the fornix, which carries fibres from the hippocampal formation, chiefly the subiculum, and arches over the thalamus to end here. The main output is the mamillothalamic tract, a stout bundle that runs up to the anterior nucleus of the thalamus. A second outflow, the mamillotegmental tract, runs down to the tegmentum of the midbrain.
These connections place the mamillary bodies in the Papez circuit: hippocampus, fornix, mamillary body, mamillothalamic tract, anterior thalamic nucleus, cingulate gyrus and back to the hippocampus by way of the parahippocampal cortex. The circuit is involved in forming and recalling memories of events. In animals the lateral mamillary nucleus also carries head-direction signals used for spatial orientation.
The mamillary bodies are one of the regions most sensitive to thiamine deficiency. In Wernicke's encephalopathy, often linked with chronic alcohol misuse, they show small haemorrhages and later shrink, and the lasting memory loss of Korsakoff syndrome is linked to damage here and in the thalamus. Their atrophy can be seen on MRI.
Function and supply
- Function
- Relay in the Papez circuit, passing hippocampal output from the fornix to the anterior thalamic nucleus; important for memory of events and for spatial orientation.
- Blood supply
- Small central branches from the posterior communicating and posterior cerebral arteries, arising near the circle of Willis.
Anthromica
See the mamillary body where it really sits, with every layer of the body around it.
- Every layer, one body. Peel from muscle to bone, nerve, vessel and organ, and turn it any way.
- English and Latin. Every structure named the way your exam names it.
- Quiz until it sticks. Short drills on the structures you keep missing.
Free to start. No card.
