Group · one in each half of the brain
Motor strip
Also called Primary motor cortex, M1
A strip across the top of your brain that sends the "go" signal to your muscles.
The motor strip is a band of cortex running over the top of the brain, roughly from ear to ear like a headband. It contains a map of the body and sends the final commands that make your muscles move. Each side controls the opposite side of the body, so your left motor strip moves your right hand. In this app it includes the precentral gyrus on the outside and the paracentral lobule on the inner surface.
Where it is
Across the top of the brain, in a band just in front of the central groove, running from near each ear up over the top and down onto the inner surface between the two halves.
What it does
Commanding muscles
It sends signals down the spinal cord that tell specific muscles when and how hard to contract.
Fine skills
It gives you precise control of individual fingers, lips and tongue, essential for writing, playing music and speaking.
A map of the body
Neighboring spots control neighboring body parts, laid out like a map of the body.
Learning skills
Practice reshapes its map, so the areas for well-trained movements can grow and sharpen.
Think of it as a piano keyboard for your body: each key along the strip plays a different set of muscles, from your toes at the top to your tongue near the bottom.
Inside the motor strip
- Primary motor cortexYour brain's movement keyboard: a body map that commands every muscle you move on purpose.
- Paracentral lobuleWhere the body map tucks inside: moving and feeling your legs, feet and bladder.
Works with
- Corticospinal tractIts commands travel down this great bundle of fibers to the spinal cord.
- Spinal cordMotor neurons in the spinal cord receive its commands and pass them on to the muscles.
- Primary somatosensory cortexThe touch strip just behind it reports what your body is feeling, so movements can be corrected on the fly.
- CerebellumThe cerebellum, working through the thalamus, helps it time and fine-tune movements.
- Basal gangliaThe basal ganglia help it start the right movements and hold back the wrong ones.
- Superior frontal gyrusPlanning areas in front, like the supplementary motor area, prepare movements before it fires them off.
When it goes wrong
Stroke
A stroke affecting the motor strip or its fibers causes weakness or paralysis on the opposite side of the body. With rehabilitation, nearby areas can often take over some of the lost work.
ALS
In amyotrophic lateral sclerosis (ALS, also called motor neuron disease), the nerve cells that carry movement commands, both here and in the spinal cord, gradually die, causing worsening weakness.
Jacksonian march
A seizure starting here can cause jerking that spreads along the body map, for example from the fingers up the arm to the face.
For learning only, not medical advice. If you have a health concern, talk to a doctor.
Surprising facts
- The fibers from each side cross over at the bottom of the brainstem, which is why the left side of the brain moves the right side of the body.
- Neurosurgeon Wilder Penfield mapped this strip from the late 1920s to about 1950 by gently stimulating the brains of awake patients during epilepsy surgery, making their fingers, lips or toes twitch.
Where the name comes from
"Motor" comes from the Latin "movere", to move. "Cortex" is Latin for bark, because the outer layer of the brain wraps around it like bark around a tree.
Quick quiz
3 questions. Your answers are saved and come back in your daily review.
Which of these is a job of the motor strip?
Show the answer
Commanding muscles. It sends signals down the spinal cord that tell specific muscles when and how hard to contract.
Commanding muscles. It sends signals down the spinal cord that tell specific muscles when and how hard to contract.
The motor strip is part of which larger structure?
Show the answer
Frontal lobe. It belongs to the frontal lobe.
Frontal lobe. It belongs to the frontal lobe.
Which part fits this description? "Like a piano keyboard for your body: each key along the strip plays a different set of muscles, from your toes at the top to your tongue near the bottom."
Show the answer
Motor strip. It is the motor strip. A strip across the top of your brain that sends the "go" signal to your muscles.
Motor strip. It is the motor strip. A strip across the top of your brain that sends the "go" signal to your muscles.
These parts now come back in your daily review, just before you would forget them.
Practice these parts in 3DSources
- Physiology, Motor Cortex, StatPearls, NCBI Bookshelf
- 10.3 Our Brain Gets Involved - Responsibilities of Upper Motor Systems, OpenStax, Introduction to Behavioral Neuroscience
- A little man of some importance, Brain (Oxford Academic)
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Explore the motor strip 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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