Covers the Brodmann areas 3,1,2 within the posterior central winding (gyrus postcentralis) and is located mainly on the outside of the hemisphere.

The primary sensory cortex constitutes the cerebrum's reception area for sensory impressions from the skin and musculoskeletal system of the opposite half of the body. The areas 3,1,2 that extend, in order from front-back over the postcentral cerebral cortex (gyrus postcentralis), are usually called the primary sensory cortex (primary sensory cortex) or somato-sensory primary cortex often abbreviated to SS I.

An electrical stimulus on the SS in the bark gives rise to a buzzing, sometimes unpleasant, sensation somewhere within the opposite half of the body. Correspondingly, for example, a touch of the skin causes an electrical change (eng. = evoked potential) at a certain place in SS I on the opposite hemisphere of the brain.

If you draw up, on the surface of the posterior central winding, a map that shows where the sensations from the opposite body half are registered on the cerebral cortex and then take into account how large the area of bark is connected to a certain part of the opposite body half, you get the picture of what is called "The sensory homunculus" (homunculus = small human).

This sensory map shows that the tongue, oral cavity and pharynx send sensory signals to area 43, which is located on the part of the posterior central winding that covers the insula.

If you then move upwards along the posterior central winding, you first pass through the right-facing opposite half of the face equipped with a grotesquely large mouth (i.e. a comparatively very large area of bark receives sensory signals from the area around the mouth opening). Then follows the rest of the opposite half of the body lying upside down with a giant hand whose fingertips are particularly large and which turns into a skinny arm attached to an even skinnier torso half.

On the inside of the posterior central winding, the torso passes into the lower limb provided with a rather large foot. At the bottom of the inside, the sensory signals from the external genitalia are received.

Then one wonders: But where is the map that shows our intestines?
An intricate organ map lies on the insula bark!!