postcentralis

The postcentralis, or postcentral gyrus, is a prominent gyrus of the parietal lobe located immediately posterior to the central sulcus. It houses the primary somatosensory cortex (S1) and corresponds largely to Brodmann areas 3, 1, and 2. The postcentral gyrus receives contralateral somatosensory input via thalamic relays, mainly from the ventral posterior nucleus (VPL for the body) and the ventral posterior medial nucleus (VPM for the face). The cortex has a somatotopic organization known as the sensory homunculus, with exaggerated representation for the lips, face, hands, and fingers.

Functionally, the postcentral gyrus processes tactile information and proprioception, including touch, pressure, temperature, and nociception. It integrates these signals to support discriminative touch, texture, shape recognition, and spatial orientation. Subregions within S1 show functional specialization: area 3b primarily receives cutaneous input; area 3a processes proprioceptive information; area 1 further analyzes texture; area 2 contributes to size and shape perception and integration with proprioceptive data.

Clinical aspects include contralateral sensory deficits following damage to the postcentral gyrus, such as reduced touch, proprioception, and impaired stereognosis or two-point discrimination. Lesions may result from stroke, trauma, tumors, or cortical degeneration. The postcentral gyrus, in concert with adjacent somatosensory areas, underpins conscious perception of the body's surface and position in space.

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