Postcentral gyrus
Gyrus postcentralis
The convolution of the parietal lobe just behind the central sulcus, holding the primary somatosensory cortex for touch and body position.
At a glance
- English
- Postcentral gyrus
- Latin (TA2)
- Gyrus postcentralis
- System
- Brain and spinal cord
- Region
- Head
- Side
- Paired, left and right
About the postcentral gyrus
The postcentral gyrus is the most forward convolution of the parietal lobe. It runs obliquely down the lateral surface of the hemisphere from the superior margin, where it turns onto the medial surface as the back part of the paracentral lobule, to the lateral sulcus below. The central sulcus lies in front of it and separates it from the precentral motor gyrus; the postcentral sulcus lies behind and marks it off from the superior and inferior parietal lobules.
The gyrus contains the primary somatosensory cortex, made up of areas 3, 1 and 2 of Brodmann, arranged from front to back. Area 3 occupies the back wall of the central sulcus and receives most of the fibres from the ventral posterior nuclei of the thalamus; area 1 sits on the crest of the gyrus and area 2 on its back slope. Some authors restrict the term primary somatosensory cortex to area 3 for this reason.
Across the length of the gyrus the opposite half of the body is mapped in order, forming the sensory homunculus. The leg and foot lie on the medial surface, the trunk and arm high on the lateral surface, and the hand, face, lips and tongue lower down near the lateral sulcus. Parts with the richest touch supply, such as the fingertips and lips, have the largest areas. This map was first charted by Wilder Penfield with direct electrical stimulation during surgery.
The gyrus receives touch, vibration, pressure and joint position sense from the medial lemniscus, and pain and temperature through the spinothalamic route, all relayed by the thalamus. Damage, most often from a stroke in the middle cerebral territory, causes loss of fine touch and position sense on the opposite side, with difficulty recognising objects by feel. Seizures beginning here produce tingling that may spread along the body map.
Function and supply
- Function
- Receives and analyses touch, pressure, vibration, joint position, pain and temperature from the opposite side of the body, mapped as the sensory homunculus.
- Blood supply
- Branches of the middle cerebral artery on the lateral surface; the medial part, for the leg, from the anterior cerebral artery.
Anthromica
See the postcentral gyrus where it really sits, with every layer of the body around it.
- Every layer, one body. Peel from muscle to bone, nerve, vessel and organ, and turn it any way.
- English and Latin. Every structure named the way your exam names it.
- Quiz until it sticks. Short drills on the structures you keep missing.
Free to start. No card.
