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Information About Gyrus and Sulcus

Nicks J Apr 14, 2019
The surface of the brain forms a unique pattern of ridges and depressions, which are commonly referred to as gyri and sulci respectively. Let us elaborate more on the features that make the brain's surface wrinkly.

Did You Know?

The gyri and sulci of the brain are not fully developed at birth and take at least a year to become prominent features.
The surface of the brain is never smooth; a closer examination reveals that the surface of the brain has a wrinkled appearance. The brain's surface is convoluted having numerous ridges and crevices.
The term gyrus and sulcus are used to describe this peculiar wrinkling pattern of the brain's surface. They represent different portions of the cerebral cortex, the outer layer of the brain, often referred to as gray matter.

Gyrus Vs. Sulcus

What is it?

Gyrus: Gyri (singular: gyrus) refer to the bumps or ridges that appear on the wrinkly, folded surface of the brain. They are essentially the peaks of the fold. In short, the hills of the brain's surface are referred to as gyri.
Sulcus: Sulci (singular: sulcus) refer to the troughs or the crevices that form between folds. They are often described as valleys appearing on the surface of the brain.

Surface Area

Gyrus: The gyri accounts for 1/3rd of the surface area of the brain.

Sulcus: 2/3rd of the surface area of the brain is taken by sulci.


Gyrus: The brain's surface has numerous gyri, each having a specific function. The angular and the supra marginal gyrus are one of the most prominent gyri of the brain and are primarily involved in comprehending language. They are essentially the language areas of the brain that allow us to read, understand, and write text.
Sulcus: Sulci are involved in dividing the brain in different regions, namely the lobes and hemispheres. The central sulcus is a notable feature of the brain that helps to differentiate the frontal lobe from the parietal lobe as well as separate the motor cortex from the sensory cortex.

Absence of Folding in the Brain

If the brain of a baby is wrinkle-free or lacking in gyri or sulci, it indicates malformation of the brain, which is a cause for great concern. This condition is referred to as lissencephaly in which the brain appears smooth.
The absence of these complicated folds can cause profound mental retardation (intellectual impairment) and the size of the head may also appear abnormally small. Other symptoms in the affected baby include seizures, malformed fingers or toes, and difficulty swallowing.
On the whole, it is very necessary that the surface of the brain is full of ridges and crevices for proper mental health. These folds on the surface area of the brain play a crucial role in enhancing brain function.