Nucleus
Mammillary bodies
Also called Corpora mammillaria, Mamillary bodies
Two tiny round bumps under the brain that are key stops on the memory loop.
The mammillary bodies are a pair of small, round bumps on the underside of the brain, at the back of the hypothalamus. They receive memory signals from the hippocampus through the fornix and pass them on to the thalamus. This relay helps you form and recall memories of events. They are very sensitive to a shortage of vitamin B1 (thiamine), which can lead to serious memory loss.
Where it is
On the underside of the brain, right in the middle, just behind the stalk of the pituitary gland.
What it does
Memory relay
They pass memory signals from the hippocampus on to the front of the thalamus, through a short cable called the mammillothalamic tract.
Recalling events
They seem especially important for recalling the details of past events, rather than just feeling that something is familiar.
Sense of direction
In animal studies, cells here track which way the head is pointing, feeding an inner compass.
Part of the Papez circuit
They are a stop on a famous brain loop that links the hippocampus, thalamus and cingulate cortex.
Think of them as a small train junction on the memory line: tiny and easy to overlook, but if it breaks, the trains stop getting through.
Works with
- FornixThe fornix delivers the hippocampus's signals to them.
- SubiculumMuch of their memory input starts in the subiculum, the hippocampus's exit.
- Anterior nucleus of the thalamusThey send their output to the anterior nucleus of the thalamus, the next stop on the memory loop.
- HypothalamusThey sit at the back of the hypothalamus and are usually counted as part of it.
- Cingulate cortexBy way of the thalamus, their signals reach the cingulate cortex, which feeds back toward the hippocampus to complete the loop.
When it goes wrong
Korsakoff syndrome
A long-term lack of vitamin B1 (thiamine), most often linked to heavy alcohol use or severe malnutrition, can damage the mammillary bodies. People may lose the ability to form new memories, and may fill the gaps with made-up stories without meaning to lie.
Wernicke encephalopathy
This is the sudden, earlier stage of thiamine shortage, with confusion, unusual eye movements and unsteady walking. It is a medical emergency, but quick treatment with thiamine can often prevent lasting damage.
For learning only, not medical advice. If you have a health concern, talk to a doctor.
Surprising facts
- In 1937, James Papez proposed a loop for emotion that runs through the mammillary bodies. Today his circuit is thought to matter even more for memory.
- In Korsakoff syndrome, the mammillary bodies can shrink so much that the change is visible on brain scans.
Where the name comes from
From the Latin "mammilla", meaning little breast. Early anatomists named them for the pair of small, round bumps they form on the underside of the brain.
Learn it in a lesson
- MemoryThe hippocampus and its circuit. A short guided lesson in 3D.
Quick quiz
3 questions. Your answers are saved and come back in your daily review.
Which of these is a job of the mammillary bodies?
Show the answer
Memory relay. They pass memory signals from the hippocampus on to the front of the thalamus, through a short cable called the mammillothalamic tract.
Memory relay. They pass memory signals from the hippocampus on to the front of the thalamus, through a short cable called the mammillothalamic tract.
The mammillary bodies is part of which larger structure?
Show the answer
Limbic system. It belongs to the limbic system.
Limbic system. It belongs to the limbic system.
Which part fits this description? "Like a small train junction on the memory line: tiny and easy to overlook, but if it breaks, the trains stop getting through."
Show the answer
Mammillary bodies. It is the mammillary bodies. Two tiny round bumps under the brain that are key stops on the memory loop.
Mammillary bodies. It is the mammillary bodies. Two tiny round bumps under the brain that are key stops on the memory loop.
These parts now come back in your daily review, just before you would forget them.
Practice it and its neighbors in 3DSources
- Neuroanatomy, Mammillary Bodies, StatPearls, NCBI Bookshelf
- Wernicke-Korsakoff syndrome, MedlinePlus Medical Encyclopedia
- Mammillary bodies, Radiopaedia
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Explore the mammillary bodies in 3D
Turn it around, zoom inside and see how it connects to the rest of the brain, then test yourself with quick quizzes.
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