Difference Between Gyri and Sulci

Main Difference – Gyri vs Sulci

The brain and the spinal cord are the major components of the central nervous system in all vertebrates and some invertebrates. The brain is located in the head, close to the major sensory organs. It coordinates the functions of the body. The brain is made up of two types of tissues known as gray matter and white matter. The brain surface or the cerebral cortex is made up of gray matter that comprises neuronal cell bodies, a few axons, dendrites, glial cells, and synapses. The gray matter should be packed into a limited space inside the skull. For this purpose, the animals with large brains such as humans have a convoluted cerebral cortex. Gyri and sulci are two structures that occur as a result of a convoluted cerebral cortex. The main difference between gyri and sulci is that gyri refer to the ridges whereas sulci refer to the grooves that produce the folds.

Key Areas Covered

1. What are Gyri
– Definition, Anatomy, Notable Gyri
2. What are Sulci
– Definition, Anatomy, Notable Sulci
3. What are the Similarities Between Gyri and Sulci
– Outline of Common Features
4. What is the Difference Between Gyri and Sulci
– Comparison of Key Differences

Key Terms: Brain, Cerebral Cortex, Convolutions, Fissures, Gray Matter, Gyri, Lobes, Sulci

What are Gyri

Gyri (singular gyrus) refer to the ridges between two clefts on the cerebral surface of the brain. The clefts that surround a gyrus are called sulci. The surface area of the brain is increased by the presence of gyri. The increased surface area gives a better cognition inside a limited size by the skull. As gyri are a component of the cerebral cortex, they are made up of gray matter. Thus, they contain neuronal cell bodies, dendrites, glial cells, a few axons, and synapses. A gyrus surrounded by sulci is shown in figure 1.

Figure 1: Structure of the Cerebral Cortex

Some notable gyri are superior, middle, and inferior frontal gyri, superior, middle, and inferior temporal gyri, precentral gyrus, angular gyrus, and lingual gyrus. Some gyri are functionally important as well. As an example, the superior temporal gyrus comprises the Wernicke’s area that is important in the computation of the language. On the other hand, the precentral gyrus serves as the primary motor center of the brain. The structural abnormalities of the gyri may lead to clinical conditions such as epilepsy.

What are Sulci

Sulci (singular sulcus) refer to the grooves on the surface of the brain. They surround the gyri. The sulci are responsible for the convoluted nature of the brain. Ideally, human brain comprises a deeply convoluted nature. The deepest grooves that separate large regions of the brain are called fissures. Sulci aid the compact packing of the large cerebral cortex inside the skull. Generally, two-thirds of the surface area is hidden in the sulci. As fissures are more deep grooves, they divide the brain into lobes. The longitudinal fissure divides the brain into two hemispheres. The sulci, gyri, and fissures of the brain are shown in figure 2.

Figure 2: Sulci, Gyri, and Fissures of the Brain

The sulci patter differ from individual to another. Some of the notable sulci are central sulcus of insula, central sulcus, calcarine sulcus, hippocampal sulcus, etc.

Similarities Between Gyri and Sulci

Both gyri and sulci are produced as a result of a convoluted nature of the brain.
Both gyri and sulci can be found in the cerebral cortex of the cerebral hemispheres.
Both gyri and sulci are made up of gray matter.
Both gyri and sulci play an important in packing the brain into the skull.

Definition

Gyri: Gyri are the ridges between two clefts on the cerebral surface of the brain.

Sulci: Sulci are the grooves on the surface of the brain.

Location

Gyri: Gryi are located between sulci.

Sulci: Sulci are located between the gyri.

Significance

Gyri: Gyri are the ridges of the brain folds.

Sulci: Sulci are the grooves of the brain folds.

Fuction

Gyri: Gyri contain cell bodies of the neurons, dendrites, and synapses.

Sulci: Sulci separate the cerebral cortex into several gyri.

Examples

Gyri: Superior, middle and inferior frontal gyri, superior and middle temporal gyri, and precentral and postcentral gyri are some examples of gyri.

Sulci: Superior frontal and inferior frontal sulci, superior and inferior temporal sulci, and central sulcus are some of the examples of sulci.

Conclusion

Gyri and sulci are two types of structures produced by the convoluted nature of the brain. Gyri are the ridges of the folds while sulci are the grooves that separate the cerebral cortex into gyri. The convoluted nature of the brain aids the compact packaging of the brain in the skull. The main difference between gyri and sulci is the anatomy of each structure in the cerebral cortex.

Reference:

1. “What is a Gyrus?” Kenhub, Available here.
2. “Sulcus (Neuroanatomy).” Wikipedia, Wikimedia Foundation, 24 Dec. 2017, Available here.
3. Schnaudigel, O E. “[Anatomy of the ciliary sulcus].” Fortschritte der Ophthalmologie : Zeitschrift der Deutschen Ophthalmologischen Gesellschaft., U.S. National Library of Medicine, Available here.

Image Courtesy:

1. “Gyrus sulcus” By Albert Kok at Dutch Wikipedia – Transferred from nl.wikipedia to Commons.(Original text: eigen bewerking) (Public Domain) via Commons Wikimedia
2. “Blausen 0115 BrainStructures” By BBlausen.com staff (2014). “Medical gallery of Blausen Medical 2014”. WikiJournal of Medicine 1 (2). DOI:10.15347/wjm/2014.010. ISSN 2002-4436. – Own work (CC BY 3.0) via Commons Wikimedia