The main difference between Sulcus and Fissure is that Sulcus forms gyri on the part of the brain cerebral cortex, whereas Fissure usually divides the brain into two lobes.
Sulcus vs. Fissure
Sulcus refers to an indentation present on the surface of the brain, while fissure refers to constricted, long division on the brain surface. The sulcus is usually less deep in structure than a fissure, whereas it is generally known as the deepest groove present in the whole brain.
The main role of sulcus in the brain is to increase the surface area of the brain and helps in the continuing growth of the brain; on the contrary, the main role performs by the fissure is to divide the brain into the two hemispheres and functional lobes that carry out their function.
The increasing of surface area in the brain by sulcus helps in the continuing growth of the brain, on the flip side, the division of fissure into lobes helps in carrying out their various functions such as help in visualizing, controlling the growth and sleep, etc.
Various examples of sulcus include inferior frontal sulci and superior frontal sulci, superior temporal and inferior temporal sulci, central sulcus, etc.; on the flip side, some examples of the fissure are central fissure, longitudinal fissure, parieto-occipital Sylvain fissure, Sylvain fissure, etc.
What is Sulcus?
The sulcus is considered as channels or pits present in the cerebral cortex of the brain in neuroanatomy. Sulci are usually smaller in size and less deep than fissures; however, the largest sulci are generally known as fissures, and many times these two terms are interchangeable. Sulci is a shallower channel that forms and ambiances the gyri (ridges) by forming the specific doubled over the presence of the brain in humans and many mammals.
They are accountable for the complicated nature of the brain. Gyri in brains consist of dendrites, glial cells, neuronal cell bodies, some axons, and synapses in neurons. Sulci are very specific in their appearance and nature. So, they vary from one individual to another in their pattern.
Various prominent sulci in the cerebral cortex of humans are hippocampal sulcus, calcarine sulcus, central sulcus of the insula, and central sulcus, etc. Sulci assist the brain in the compressed stuffing of the huge cerebral cortex in the skull. Usually, the two-third size of the brain is covered by sulci because the main role of sulcus in the brain is to increase the surface area of the brain and the depression, pits in the sulcus provide surface area for assisting in the continuing growth of the brain.
The complex structure of the cerebral cortex could be seen in the first five months of embryonic development and completely developed in the first year after giving birth. The development of sulcus could vary in individuals by epigenetic, potential influences of genetic, and maybe environmental factors may affect the growth of sulcus that varies in individuals. Some studies show that the thickness of the cortical sulci increases not only with a factor of age but may also degeneration in the perceptive in the advanced years.
Various examples of sulcus include inferior frontal sulci and superior frontal sulci, superior temporal and inferior temporal sulci, central sulcus, etc.
Types of Sulcus Based on Functionality
- Limiting Sulcus: This sulcus divides at its bases into its different portions that vary in functionality and also change structurally. For example, central sulcus presents between sensory and motor areas.
- Axial Sulcus: This sulcus forms in the faster forming homogeneous portion in the brain in the form of the long axis. For example, postcalcarine sulcus present in the lengthy alliance of the striate portion.
- Operculated Sulcus: This sulcus divides through its edges in two different portions and consists of the third portion in the walls of the sulcus. For example, an Operculated sulcus is a lunate sulcus that separates the Para striate areas and striate.
Types of Sulcus Based on the Formation
- Primary Sulcus: This is formed independently before birth, e.g., central sulcus.
- Secondary Sulcus: This sulcus formed by other factors than an exciting growth factor in the attached portions of the cortex. E.g., lateral and parieto-occipital sulci.
What is Fissure?
A fissure is considered as a natural separation, extended branched, channels, deep undulation, or split into some portions of the brain-body. Fissure sometimes called sulcus in the brain. Fissures are generally the deepest channels than sulcus and divide large regions of the brain into hemispheres known as lobes.
The two brain hemispheres left and right are divided by the longitudinal fissure. Normally, the left side of the hemisphere of the brain dominates the right side of the body, whereas the right hemisphere dominates the left side of the body.
The left cerebral hemisphere of the brain is usually responsible for language, speech, linear sequential processing, writing. Though, the right cerebral hemisphere of the brain is responsible for emotions, visual-spatial activities, music, drawing, and parallel processing. Each hemisphere left or right is separated into four different lobes: parietal lobe, occipital lobe, temporal lobe, and frontal lobe.
The three fissures Sylvain fissure, parieto-occipital fissure, and central fissure divides the four lobes from each other. Fissure could also be found as an abnormal area or sore, which is the best ordinarily present in the anus of animals known as anal fissure. Some examples of the fissure are a central fissure, longitudinal fissure, parieto-occipital Sylvain fissure, Sylvain fissure, etc.
Lobes of Hemispheres
- Frontal Lobe: It is responsible for awareness, speech, planning, and various other emotional expressions other than controlled movements.
- Parietal Lobe: It consists of the motor cortex, which is involved in somatosensory observations, and this type of observation, the body responds to the various senses attained from acoustic, memory, and visual functions. This lobe is considered as the chief sensory area for touch senses.
- Occipital Lobe: This lobe obtains and analyzes graphic facts.
- Temporal Lobe: This lobe is concerned with hearing and smell.
Types of Fissure in Brain
- Fissure of Bichat: It establishes underneath the corpus Callosum present in the cerebellum of the brain.
- Broca’s Fissure: Establish on the third side the left anterior folding of the brain.
- Clevenger’s Fissure: Establish in the lower temporal lobe of the brain.
- Transverse Fissure and Horizontal Fissure: Usually establish among the cerebellum and the cerebrum. A “transverse fissure” could also originate in the lungs and liver.
- A groove present on the surface of the brain generally refers to sulcus, while narrow, long division on the brain surface refers to fissure.
- In the cerebral cortex, the gyri are present from where sulcus forms and extend; on the other hand, in the brain, the lobes are formed when the partition of the brain occurs through the fissure.
- The sulcus is usually less deep in structure, whereas fissure is generally known as the deepest groove present in the brain.
- In the brain, the main role of the sulcus is to intensify the surface area of the brain; on the contrary, to divide the brain into the two hemispheres is the main role performs by the fissure.
- The continuing growth of the brain is assisted by increasing of surface area in the brain by a sulcus, on the flip side, the division of fissure into lobes helps in carrying out their various functions such as help in visualizing, controlling the growth and sleep, etc.
- Various examples of sulcus include inferior frontal sulci and superior frontal sulci, superior temporal and inferior temporal sulci, central sulcus, etc.; on the flip side, some examples of the fissure are central fissure, longitudinal fissure, parieto-occipital Sylvain fissure, Sylvain fissure, etc.
The above discussion concludes that the two types of grooves are present in the cerebral cortex of the brain sulcus and fissure. Sulcus gives rise to gyri by dividing the cerebral cortex, while fissure gives rise to lobes by separating the large parts of the brain. The sulcus is less deep than a fissure.