Division
Pons
Also called Pons Varolii
The "bridge" linking cortex to cerebellum, and a key player in dreams and breathing.
The pons is the rounded bulge in the middle of the brainstem, between the midbrain and the medulla. It is a huge relay: signals from the cortex pass through it on their way to the cerebellum. It also helps smooth your breathing rhythm and helps switch on REM sleep, the stage of vivid dreams. Several cranial nerves for the face, jaw, eyes and ears connect here.
Where it is
In the middle of the brainstem, right in front of the cerebellum, between the midbrain above and the medulla below.
What it does
Cortex-to-cerebellum relay
Signals from the cortex stop here and are passed across to the cerebellum, so it knows what you plan to do.
Breathing rhythm
Groups of cells here help smooth your breathing and time the switch between breathing in and out.
Dream sleep
It helps switch on REM sleep and keep your body muscles limp, so you do not act out your dreams.
Face and senses
Cranial nerves for chewing, feeling in the face, facial expressions, eye movement, hearing and balance connect here.
Think of it as a busy bridge between two cities, carrying a constant flow of traffic from the cortex over to the cerebellum.
Inside the pons
- Locus coeruleusThe "blue spot": a tiny cluster that sets how alert and ready for action you are.
- Raphe nucleiA chain of cell clusters down the brainstem's middle that makes most brain serotonin.
Works with
- CerebellumIts fibers form the biggest stalk into the cerebellum, carrying a flood of signals from the cortex.
- Primary motor cortexThe motor cortex sends copies of its commands down to the pons.
- Locus coeruleusThis tiny noradrenaline center sits inside the pons.
- Trigeminal nerve (V)This big nerve for feeling in the face and for chewing plugs into the pons.
- Facial nerve (VII)This nerve, which moves your facial expressions, starts at the lower edge of the pons.
- Medulla oblongataIt works with breathing centers in the medulla to keep your breathing smooth.
When it goes wrong
Locked-in syndrome
A stroke in the front of the pons can paralyze nearly the whole body while the mind stays fully awake. People can often still blink and move their eyes up and down, and use them to communicate.
Acting out dreams
In REM sleep behavior disorder, the muscle "off switch" fails and people kick or punch in their sleep. It can be an early warning sign of Parkinson's disease.
For learning only, not medical advice. If you have a health concern, talk to a doctor.
Surprising facts
- Each of the two thick stalks joining the pons to the cerebellum carries over 20 million nerve fibers. The main movement pathway from the cortex to the spinal cord has only about a million.
By the numbers
Where the name comes from
Latin for "bridge", because its band of fibers seemed to bridge the two halves of the cerebellum. Its other name, pons Varolii, honors the 16th-century Italian anatomist Costanzo Varolio, who first described it.
Learn it in a lesson
- The brainstem and cranial nervesLife support and the nerves of the head. 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 pons?
Show the answer
Cortex-to-cerebellum relay. Signals from the cortex stop here and are passed across to the cerebellum, so it knows what you plan to do.
Cortex-to-cerebellum relay. Signals from the cortex stop here and are passed across to the cerebellum, so it knows what you plan to do.
The pons is part of which larger structure?
Show the answer
Brainstem. It belongs to the brainstem.
Brainstem. It belongs to the brainstem.
Which part fits this description? "Like a busy bridge between two cities, carrying a constant flow of traffic from the cortex over to the cerebellum."
Show the answer
Pons. It is the pons. The "bridge" linking cortex to cerebellum, and a key player in dreams and breathing.
Pons. It is the pons. The "bridge" linking cortex to cerebellum, and a key player in dreams and breathing.
These parts now come back in your daily review, just before you would forget them.
Practice these parts in 3DSources
- Neuroanatomy, Pons, StatPearls, NCBI Bookshelf
- Pons, Radiopaedia
- Locked-in Syndrome, StatPearls, NCBI Bookshelf
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Explore the pons 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