Organ
Brainstem
Also called Brain stem
The stalk connecting brain and body, running breathing, heartbeat and wakefulness.
The brainstem is the stalk at the base of the brain that connects it to the spinal cord. It has three parts: the midbrain, the pons and the medulla. Nearly every message between your brain and your body passes through it. It also runs the things you never think about, like breathing, heartbeat, blood pressure and staying awake.
Where it is
At the base of the brain, running down from under its center to the top of the neck, where it becomes the spinal cord.
What it does
Life support
It automatically controls breathing, heart rate, blood pressure and swallowing, day and night.
The main highway
Nearly all nerve signals between the brain and the body travel up and down through it.
Staying awake
Networks of cells running through it keep the rest of the brain awake and alert.
Cranial nerve hub
Ten of the twelve pairs of cranial nerves, which serve the face, eyes, ears, mouth and more, connect to it.
Chemical broadcasting
Small clusters here make much of the brain's dopamine, serotonin and noradrenaline and send them across the whole brain.
Think of it as the engine room of a ship: out of sight below deck, but nothing on board works without it.
Inside the brainstem
- MidbrainThe top of the brainstem: eye reflexes, hearing relays and dopamine factories.
- PonsThe "bridge" linking cortex to cerebellum, and a key player in dreams and breathing.
- Medulla oblongataYour life-support center: breathing, heartbeat, blood pressure and swallowing on autopilot.
- Cranial nervesTwelve pairs of nerves wired straight from the brain to your eyes, face, throat, and gut.
- Spinal cordThe body's main information highway, and home to lightning-fast reflexes.
Works with
- Spinal cordThe brainstem flows straight into the spinal cord at the base of the skull.
- CerebellumThe cerebellum is attached to the back of the brainstem by three thick stalks of fibers.
- ThalamusSensory signals rise through the brainstem to the thalamus, the relay station for the cortex.
- HypothalamusThe hypothalamus sends orders down to brainstem centers that help control the heart and gut.
- Cranial nervesMost of the cranial nerves plug directly into the brainstem.
- Vagus nerve (X)This long nerve leaves the brainstem to help slow the heart and run digestion.
When it goes wrong
Coma
Damage to the wake-up networks in the brainstem, for example from a stroke, can cause a coma.
Brain death testing
When doctors test for brain death, they check brainstem reflexes, like whether the pupils react to light and whether the person tries to breathe.
Brainstem stroke
So much is packed into such a small space that even a small stroke here can cause several problems at once, like double vision, trouble swallowing and weakness.
For learning only, not medical advice. If you have a health concern, talk to a doctor.
Surprising facts
- It is only a few centimeters long, yet serious damage to it can be deadly, because it runs breathing and heartbeat.
- Animals with a backbone, from fish to frogs to people, all have a brainstem built on the same basic plan.
By the numbers
Where the name comes from
A plain English name for its shape: like the stem of a flower, it holds up the brain above it.
Learn it in a lesson
- The big pictureCerebrum, cerebellum and brainstem. A short guided lesson in 3D.
Quick quiz
2 questions. Your answers are saved and come back in your daily review.
Which of these is a job of the brainstem?
Show the answer
Life support. It automatically controls breathing, heart rate, blood pressure and swallowing, day and night.
Life support. It automatically controls breathing, heart rate, blood pressure and swallowing, day and night.
Which part fits this description? "Like the engine room of a ship: out of sight below deck, but nothing on board works without it."
Show the answer
Brainstem. It is the brainstem. The stalk connecting brain and body, running breathing, heartbeat and wakefulness.
Brainstem. It is the brainstem. The stalk connecting brain and body, running breathing, heartbeat and wakefulness.
These parts now come back in your daily review, just before you would forget them.
Practice these parts in 3DSources
- Neuroanatomy, Brainstem, StatPearls, NCBI Bookshelf
- Brainstem Stroke, StatPearls, NCBI Bookshelf
- Brain Death, StatPearls, NCBI Bookshelf
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Explore the brainstem in 3D
Turn it around, zoom inside and see how it connects to the rest of the brain, then test yourself with quick quizzes.
Open it in 3D