What separates the strip that moves the body from the strip that feels it, and why are lips and hands so large on both maps? · Grey Matter

The central sulcus, a deep groove running across the top of each hemisphere, has the primary motor cortex on its front bank (the precentral gyrus) and the primary somatosensory cortex on its back bank (the postcentral gyrus).

What separates the strip that moves the body from the strip that feels it, and why are lips and hands so large on both maps?

The central sulcus, a deep groove running across the top of each hemisphere, has the primary motor cortex on its front bank (the precentral gyrus) and the primary somatosensory cortex on its back bank (the postcentral gyrus). Penfield mapped both by stimulating patients' cortex during surgery and found two matching body maps, the homunculi, with the leg on the midline and the face low on the side. The size of each part on the map follows how finely it is controlled or felt, which is why lips, tongue and fingers take far more cortex than the trunk or the back.