Difference Between Sulcus and Fissure

Main Difference – Sulcus vs Fissure

The brain is the main functional unit of the central nervous system of all vertebrates and some invertebrates. The surface of the brain is known as the cerebral cortex. The cerebral cortex is made up of gray matter, containing neuronal cell bodies, dendrites, glial cells, a few axons, and synapses. Sulcus and Fissure are two types of grooves found in the cerebral cortex. Both sulci and fissures aid in the compact package of the brain in the skull. The main difference between sulcus and fissure is that sulcus produces gyri on the cerebral cortex whereas fissure separates the brain into lobes.

Key Areas Covered

1. What is a Sulcus
– Definition, Facts, Notable sulci
2. What is a Fissure
– Definition, Facts, Types of fissures
3. What are Similarities Between Sulcus and Fissure
– Outline of Common Features
4. What is the Difference Between Sulcus and Fissure
– Comparison of Key Differences

Key Terms: Brain, Cerebral Cortex, Convolutions, Fissure, Gyri, Lobes, Sulcus

What is a Sulcus

A sulcus (plural sulci) refers to a groove on the surface of the brain. The sulci are responsible for the convoluted nature of the brain. Sulci produce gyri, the ridges. The gyri contain neuronal cell bodies, dendrites, glial cells, a few axons, and synapses. The sulci pattern differ from individual to another. Some of the notable sulci are central sulcus of insula, central sulcus, calcarine sulcus, hippocampal sulcus, etc. Different sulci and gyri in the brain are shown in figure 1.

Figure 1: Sulci and Gyri

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. The convolutions of the cerebral cortex appear at about five months of the embryonic development and are fully developed during the first year after birth.

What is a Fissure

A fissure refers to a long, narrow splittings on the surface of the brain. Thus, they are the deepest grooves that separate large regions of the brain known as lobes. The longitudinal fissure divides the brain into two hemispheres as left and right. Generally, the right hemisphere of the brain controls the left side of the body while the left hemisphere of the brain controls the right side of the body. The left cerebral hemisphere is responsible for writing, language, speech, and linear sequential processing. However, the right cerebral hemisphere is responsible for music, drawing, emotions, visual-spatial activities, and parallel processing. Each hemisphere further divides into four lobes: frontal lobe, parietal lobe, temporal lobe, and occipital lobe. The three fissures that separate the four lobes from each other are the central fissure, Sylvian fissure, and the parieto-occipital Sylvian fissure. The four lobes of a hemisphere are shown in figure 2.

Figure 2: Four Lobes

The front lobe is responsible for planning, awareness, organization, speech, and emotional expressions other than voluntary movements. The temporal lobe contains the auditory cortex. The parietal lobe contains a motor cortex, involved in the somatosensory perceptions. In the somatosensory perception, the body responds to the senses obtained from visual, acoustic, and memory functions. The occipital lobe contains the visual cortex. The parietal lobe is the main sensory area for touch. It also integrates sensory information along with the spatial sense and navigation.

Similarities Between Sulcus and Fissure

Sulcus and fissure are two types of grooves in the cerebral cortex.
Both sulcus and fissure are responsible for the convoluted nature of the cerebral cortex.
Both sulcus and fissure separate the cerebral cortex into different parts.
Both sulcus and fissure are made up of gray matter.
Both sulcus and fissure are important in the packing of large brains into the skull.

Definition

Sulcus: A sulcus refers to a groove on the surface of the brain.

Fissure: A fissure refers to a long, narrow splitting on the surface of the brain.

Deepness

Sulcus: The sulcus is less deep.

Fissure: The fissure is the deepest groove in the brain.

Produce

Sulcus: The sulcus produces gyri.

Fissure: The fissure produces lobes.

Role

Sulcus: The sulci of the brain increase the surface area of the brain.

Fissure: The fissures separate the brain into functional lobes.

Examples

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

Fissure: Longitudinal fissure, central fissure, Sylvian fissure, and parieto-occipital Sylvian fissure are some examples of fissures.

Conclusion

Sulcus and fissure are two types of grooves that occur in the cerebral cortex, separating it into different areas. Fissures are deeper than sulci. Sulci separate the cerebral cortex into gyri while fissures separate the cerebral cortex into lobes. The main difference between sulcus and fissure is the role of each type of grooves in the cerebral cortex.

Reference:

1. “Sulcus (Neuroanatomy).” Wikipedia, Wikimedia Foundation, 24 Dec. 2017, Available here.
2. Schnaudigel, O E. “[Anatomy of the ciliary sulcus].” Fortschritte der Ophthalmologie : Zeitschrift der Deutschen Ophthalmologischen Gesellschaft., U.S. National Library of Medicine, Available here.
3. “Cerebral Cortex – Lobes, Fissures, Gyri, and Sulci.” GetBodySmart, 8 Dec. 2017, Available here.

Image Courtesy:

1. “Gray726 central sulcus” By Gray – File:Gray726.svg (Public Domain) via Commons Wikimedia
2. “LobesCaptsLateral” By Sebastian023 (CC BY-SA 3.0) via Commons Wikimedia