What is the Difference Between Precentral and Postcentral Gyrus

The key difference between precentral and postcentral gyrus is that precentral gyrus is an important structure on the lateral surface of the frontal lobe and regulates voluntary motor movements of the body, while postcentral gyrus is a prominent structure on the lateral parietal lobe of the brain and regulates involuntary movements of the body.

A gyrus is a bump or ridge on the cerebral cortex, which is the outermost layer of the brain. Gyri are made of grey matter, which consists of nerve cell bodies and dendrites. They are unique structures that increase the surface area of the brain. This large surface area gives a better cognition without increasing the size of the brain. There are many specific gyri playing important roles in the functions of the brain. Precentral and postcentral gyri are the two main gyri found in the brain.

CONTENTS

1. Overview and Key Difference
2. What is Precentral Gyrus
3. What is Postcentral Gyrus
4. Similarities – Precentral and Postcentral Gyrus
5. Precentral vs Postcentral Gyrus in Tabular Form
6. Summary – Precentral vs Postcentral Gyrus

What is Precentral Gyrus?

Precentral gyrus is an important structure on the lateral surface of the frontal lobe and regulates voluntary movements of the body. It is located on the lateral surface of the frontal lobe and anterior to the central sulcus running parallel to it. The primary motor cortex is situated in the precentral gyrus. Several motor pathways originate within the precentral gyrus. In addition to the motor pathways, corticospinal tract, corticobulbar tract, and cortico-rubrospinal tract also begin from the precentral gyrus.

Figure 01: Precentral Gyrus

Precentral gyrus has large neurons called Betz cells. The functional organization of precentral gyrus is by clusters of Betz cells, and they are represented by inverted homunculus. The inferior portion of the precentral gyrus innervates the head and face regions. Medially and inferiorly, the precentral gyrus is bound by the cingulate gyrus, while it is bound by the Sylvian fissure laterally and inferiorly.

What is Postcentral Gyrus?

Postcentral gyrus is a prominent structure on the lateral parietal lobe of the brain that regulates involuntary movements of the body. It lies between the central sulcus and postcentral sulcus. Postcentral gyrus contains the primary somatosensory cortex. This enables the body to identify somatic sensations such as pressure, touch, pain, and temperature. The primary somatosensory cortex identifies sensations in the contralateral portion, and this region is called the sensory homunculus.

Figure 02: Postcentral Gyrus

The main blood supply to the postcentral gyrus is from the anterior cerebral artery and the middle cerebral artery. The anterior cerebral artery perfuses the medial third of the postcentral gyrus, while the middle cerebral artery perfuses the lateral two-thirds of the postcentral gyrus. Damage to postcentral gyrus primarily results in contralateral somatosensory disturbances.

What are the Similarities Between Precentral and Postcentral Gyrus?

• Precentral and postcentral gyrus are located in the cerebral cortex of the brain.
• Precentral gyrus lies in front of the postcentral gyrus
• The presence of both gyri increases the surface area of the brain.

What is the Difference Between Precentral and Postcentral Gyrus?

Precentral gyrus controls the voluntary motor movements, whereas postcentral gyrus control involuntary functions. Thus, this is the key difference between precentral and postcentral gyrus. Moreover, precentral gyrus is located on the lateral side of each cerebral hemisphere of the frontal lobe, while postcentral gyrus is located on the lateral surface of the parietal lobe of the cerebral cortex. In addition, precentral gyrus provides a site for the primary motor cortex, while postcentral gyrus provides a site for the primary somatosensory cortex.

The below infographic presents the differences between postcentral and precentral gyrus in tabular form for side by side comparison.

Summary – Precentral vs Postcentral Gyrus

Precentral and postcentral gyri are two main gyri found in the brain. Precentral gyrus controls voluntary motor movements while postcentral gyrus controls involuntary functions. Precentral gyrus is found on the lateral surface of the frontal lobe and anterior to the central sulcus, while postcentral gyrus is situated in the lateral parietal lobe of the brain. So, this is the key difference between precentral and postcentral gyrus.

Reference:

1. “Neuroanatomy, Precentral Gyrus.” StatPearls. NCBI Bookshelf.
2. “Neuroanatomy, Postcentral Gyrus.” National Center for Biotechnology Information, U.S. National Library of Medicine.

Image Courtesy:

1. “Precentral gyrus – superior view” By Anatomography – en:Anatomography (CC BY-SA 2.1 jp) via Commons Wikimedia
2. “Postcentral gyrus” By Jimhutchins (talk) – The original image was uploaded on en.wikipedia as en:Image:Postcentral_gyrus.png (CC BY-SA 3.0) via Commons Wikimedia

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