Nucleus
Raphe nuclei
Also called Raphe system
A chain of cell clusters down the brainstem's middle that makes most brain serotonin.
The raphe nuclei are a chain of small cell clusters running down the middle of the brainstem. Together they make most of the brain's serotonin, a chemical messenger that affects mood, sleep, appetite and pain. The upper clusters send serotonin up to nearly the whole brain. The lower clusters send it down into the spinal cord.
Where it is
Along the midline of the brainstem, from the midbrain down through the pons to the medulla.
What it does
Mood
Serotonin from here helps keep your mood and emotions steady.
Sleep and waking
Its activity rises and falls with your daily cycle of sleeping and waking.
Appetite
It helps regulate your appetite.
Pain control
Its lower clusters send signals down the spinal cord that can turn pain down.
Breathing and body heat
Its serotonin also helps adjust your breathing and body temperature.
Think of it as a sprinkler line running down the middle of a garden, misting serotonin over everything from top to bottom.
Works with
- SerotoninThis is the chemical messenger it makes and sends out.
- Serotonin neuronIt is made of these serotonin-releasing nerve cells.
- Prefrontal cortexSerotonin from here shapes mood and decision making in this front region.
- HippocampusIts signals reach the hippocampus, influencing memory and mood.
- HypothalamusIt helps the hypothalamus manage sleep, appetite and body temperature.
- Spinal cordIts lower clusters send fibers down the cord to turn pain signals down.
When it goes wrong
Depression and anxiety
Common antidepressants called SSRIs, such as fluoxetine, keep serotonin working for longer. Depression is more complicated than just "low serotonin", but this system plays a part.
For learning only, not medical advice. If you have a health concern, talk to a doctor.
Surprising facts
- About 90% of your body's serotonin is actually in your gut, not your brain. The brain makes its own, mostly here in the raphe nuclei.
- Its cells are most active when you are awake and moving about, and they quiet down during sleep.
- Psychedelic drugs like psilocybin act mainly on serotonin receptors, the same docking points that serotonin from here uses.
Where the name comes from
From the Greek word for "seam". They line up along the midline of the brainstem, like stitches along a seam.
Quick quiz
3 questions. Your answers are saved and come back in your daily review.
Which of these is a job of the raphe nuclei?
Show the answer
Mood. Serotonin from here helps keep your mood and emotions steady.
Mood. Serotonin from here helps keep your mood and emotions steady.
The raphe nuclei is part of which larger structure?
Show the answer
Pons. It belongs to the pons.
Pons. It belongs to the pons.
Which part fits this description? "Like a sprinkler line running down the middle of a garden, misting serotonin over everything from top to bottom."
Show the answer
Raphe nuclei. It is the raphe nuclei. A chain of cell clusters down the brainstem's middle that makes most brain serotonin.
Raphe nuclei. It is the raphe nuclei. A chain of cell clusters down the brainstem's middle that makes most brain serotonin.
These parts now come back in your daily review, just before you would forget them.
Practice it and its neighbors in 3DSources
- Neuroanatomy, Nucleus Raphe, StatPearls, NCBI Bookshelf
- Biochemistry, Serotonin, StatPearls, NCBI Bookshelf
- Psychedelic and Dissociative Drugs, National Institute on Drug Abuse (NIDA)
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