Postcentral Gyrus

ANATOMY AIIMS, GROSS ANATOMY, EMBRYOLOGY, NEUROANATOMY, MICROANATOMY, APPLIED/ CLINICAL ANATOMY

The Postcentral Gyrus: Unraveling the Sensory Map

The postcentral gyrus, nestled within the parietal lobe of the cerebral cortex, is a remarkable brain structure that plays a pivotal role in our perception of touch and bodily sensations. Let’s explore its anatomy, function, and significance.

Anatomy and Location

1. Position: The postcentral gyrus lies posterior to the central sulcus (also known as the ascending parietal gyrus).
2. Primary Somatosensory Cortex: It houses the primary somatosensory cortex, which serves as the main sensory receptive area for the sense of touch.
3. Sensory Homunculus:
   • Just like the primary motor cortex has a motor homunculus, the postcentral gyrus hosts a sensory homunculus.
   • This map represents different body parts and their corresponding sensory representations within the cortex.
   • The size of each body part in the sensory homunculus corresponds to the density of sensory receptors in that area.

Function

1. Processing Touch and Sensations:
   • When you touch something, receptors in your skin send signals to the postcentral gyrus.
   • It processes these signals, allowing you to perceive sensations like pressure, temperature, vibration, and pain.
2. Somatotopic Organization:
   • The postcentral gyrus has a precise somatotopic organization.
   • Different areas of the gyrus correspond to specific body regions.
   • For example:
     • The leg area is located medially (closer to the midline).
     • The head and face area are situated laterally on the convex side of the cerebral hemisphere.
     • The arm and hand motor area occupies the space between the leg and face areas.

Blood Supply

• The postcentral gyrus receives blood supply from the anterior cerebral artery (ACA) and the middle cerebral artery (MCA)

Clinical Significance

• Lesions in the postcentral gyrus can lead to sensory deficits, affecting touch perception on the contralateral side of the body.
• Neurosurgeon Wilder Penfield initially defined the primary somatosensory cortex through surface stimulation studies, contributing significantly to our understanding of this critical brain region.

In summary, the postcentral gyrus is our gateway to the world of touch and sensations. Its intricate organization allows us to feel, explore, and interact with our environment, making it an essential part of our sensory experience.