Nucleus · one in each half of the brain
Interposed nucleus
Also called Emboliform and globose nuclei, Nucleus interpositus
The middle cerebellar nucleus, correcting arm and leg movements as they happen.
The interposed nucleus sits between the dentate and fastigial nuclei. In humans it is made of two small parts, the emboliform and globose nuclei. It gets signals from the strip of cerebellum just beside the middle, which tracks your limbs through the spinal cord. It uses them to correct arm and leg movements while they are happening.
Where it is
Deep inside the cerebellum, between the large dentate nucleus on the outside and the fastigial nucleus near the middle.
What it does
Correcting on the fly
It compares what your limbs are doing with what you meant to do and fixes errors mid-movement.
Limb coordination
It smooths out reaching, grasping and stepping.
Learning precise timing
It helps you learn well-timed reflexes, like blinking just before a puff of air hits your eye.
Think of it as a GPS that recalculates your route every second, nudging your hand back on course in the middle of a reach.
Works with
- Red nucleusIts output crosses to the other side and reaches the red nucleus, which can send signals down to the spinal cord.
- Ventral lateral nucleus of the thalamusIt also sends corrections through this relay in the thalamus to the motor cortex.
- Spinal cordUpdates from the spinal cord about your limbs feed the strip of cerebellum that drives it.
- Anterior lobe of the cerebellumMuch of its input comes from the side strips of the anterior lobe.
- Purkinje cellPurkinje cells in the strip beside the vermis send their signals down to it.
When it goes wrong
Overshooting and tremor
Damage can make the arm or leg on the same side overshoot its targets and shake while moving.
For learning only, not medical advice. If you have a health concern, talk to a doctor.
Surprising facts
- In classic experiments, rabbits learned to blink at a sound that warned of a puff of air. When the deep nuclei here, including this one, were damaged, the learned blink disappeared, although they still blinked at the puff itself.
- The finger-to-nose test, touching your nose and then a doctor's finger again and again, checks this part of the cerebellum, among others. Overshooting or shaking can point to trouble here.
Where the name comes from
"Interposed" comes from Latin for "placed between", because it lies between the other two. Its parts are named for their shapes: emboliform means "plug-shaped" and globose means "ball-shaped".
Quick quiz
3 questions. Your answers are saved and come back in your daily review.
Which of these is a job of the interposed nucleus?
Show the answer
Correcting on the fly. It compares what your limbs are doing with what you meant to do and fixes errors mid-movement.
Correcting on the fly. It compares what your limbs are doing with what you meant to do and fixes errors mid-movement.
The interposed nucleus is part of which larger structure?
Show the answer
Deep cerebellar nuclei. It belongs to the deep cerebellar nuclei.
Deep cerebellar nuclei. It belongs to the deep cerebellar nuclei.
Which part fits this description? "Like a GPS that recalculates your route every second, nudging your hand back on course in the middle of a reach."
Show the answer
Interposed nucleus. It is the interposed nucleus. The middle cerebellar nucleus, correcting arm and leg movements as they happen.
Interposed nucleus. It is the interposed nucleus. The middle cerebellar nucleus, correcting arm and leg movements as they happen.
These parts now come back in your daily review, just before you would forget them.
Practice it and its neighbors in 3DSources
- Projections from the Cerebellum, Neuroscience, 2nd edition (Purves et al.), NCBI Bookshelf
- Neuroanatomy, Cerebellum, StatPearls, NCBI Bookshelf
- 18.2 Implicit Memories: Associative vs. Nonassociative Learning, OpenStax, Introduction to Behavioral Neuroscience
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Explore the interposed nucleus in 3D
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