Cortical area · one in each half of the brain
Primary somatosensory cortex
Also called Primary somatosensory cortex, S1, Brodmann areas 3, 1 and 2
Your touch map: every patch of skin has its own spot on this strip.
This strip of cortex is the brain's main arrival hall for touch. Signals about pressure, vibration, temperature, pain and body position travel up from your skin and joints, pass through the thalamus, and land here. Each body part has its own spot, laid out in order like a map. Very sensitive parts, like the lips and fingertips, get much more space than the back or the legs.
Where it is
A long vertical strip running from the top of the head down toward each ear. It sits just behind the central sulcus, the deep groove that divides the frontal and parietal lobes, right behind the motor strip.
What it does
Feeling touch
It tells you what is touching you and exactly where: a light brush on the cheek, a firm grip on the hand, a buzz on the fingertip.
Sensing body position
Sensors in your muscles and joints report here, so you know how your fingers are bent without looking.
Pain and temperature
It helps pinpoint where something hurts or feels hot or cold, working with other areas that add the unpleasant feeling.
Feeling shapes and textures
It helps you tell silk from sandpaper, and, with areas behind it, recognize a key in your pocket just by feel.
The sensory homunculus
The body is mapped upside down along the strip: feet and legs near the top of the head, then the trunk, hand and face lower down.
Think of it as a giant piano keyboard where every key is a patch of your skin, and each touch plays its own key.
Works with
- Ventral posterior nucleus of the thalamusThis thalamus relay station sorts incoming touch signals and sends each one to the matching spot on the strip.
- Primary motor cortexThe motor strip sits right next door, and the two constantly talk so your movements can adjust to what you feel.
- Trigeminal nerve (V)Touch from your face travels in through the trigeminal nerve, then up through the thalamus to the face area of this strip.
- Superior parietal lobuleIt passes touch and position information back to this area, which builds a fuller sense of your body in space.
- InsulaThe insula, part of the brain's pain network, helps add how sensations feel, such as how unpleasant a pain is.
When it goes wrong
Numbness after a stroke
Damage here can leave part of the opposite side of the body numb or tingly. Which part depends on which spot of the map is hit.
Phantom limb feelings
After an arm is lost, the brain map can rewire as neighboring areas take over its space. This may help explain why touching nearby skin can be felt in the missing limb.
Sensory seizures
A seizure that starts here may cause tingling or pins and needles that spread across the body in the same order as the map.
For learning only, not medical advice. If you have a health concern, talk to a doctor.
Surprising facts
- The brain itself has no pain sensors. That is how surgeon Wilder Penfield could gently stimulate this strip in awake patients in the 1930s to 1950s. They reported sensations in places like the hand, lips or toes, which let him draw the famous body map.
- If you drew a person with body parts sized by how much of this strip they use, you would get the "homunculus" (Latin for "little man"): huge lips, huge hands and a tiny back.
- Each side of the brain feels the opposite side of the body. Your left hand reports to your right postcentral gyrus.
Where the name comes from
"Post" is Latin for "behind", so the postcentral gyrus is the ridge just behind the central sulcus. "Somatosensory" mixes the Greek "soma" (body) with "sensory".
Learn it in a lesson
- Moving and feelingThe motor and sensory strips. 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 primary somatosensory cortex?
Show the answer
Feeling touch. It tells you what is touching you and exactly where: a light brush on the cheek, a firm grip on the hand, a buzz on the fingertip.
Feeling touch. It tells you what is touching you and exactly where: a light brush on the cheek, a firm grip on the hand, a buzz on the fingertip.
The primary somatosensory cortex is part of which larger structure?
Show the answer
Parietal lobe. It belongs to the parietal lobe.
Parietal lobe. It belongs to the parietal lobe.
Which part fits this description? "Like a giant piano keyboard where every key is a patch of your skin, and each touch plays its own key."
Show the answer
Primary somatosensory cortex. It is the primary somatosensory cortex. Your touch map: every patch of skin has its own spot on this strip.
Primary somatosensory cortex. It is the primary somatosensory cortex. Your touch map: every patch of skin has its own spot on this strip.
These parts now come back in your daily review, just before you would forget them.
Practice it and its neighbors in 3DSources
- Neuroanatomy, Postcentral Gyrus, StatPearls, NCBI Bookshelf
- Central Processing, OpenStax, Anatomy and Physiology 2e
- Anesthesia for Awake Craniotomy, StatPearls, NCBI Bookshelf
Spotted a mistake? Tell us.
Explore the primary somatosensory cortex 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