Dorling Kindersley / Getty Images Updated on January 28, 2020 The corpus callosum is a thick band of nerve fibers that divides the
cerebral cortex lobes into left and right hemispheres. It connects the left and right sides of the brain, allowing for communication between both
hemispheres. The corpus callosum transfers motor, sensory, and cognitive information between the brain hemispheres. The corpus callosum is the largest fiber bundle in the brain, containing nearly 200 million axons. It is composed of
white matter fiber tracts known as commissural fibers. It is involved in several functions of the body including:
From anterior (front) to posterior (back), the corpus callosum can be divided into regions known as the rostrum, genu, body, and splenium. The rostrum and genu connect the left and right frontal lobes of the brain. The body and splenium connect the hemispheres of the temporal lobes and the hemispheres of the occipital lobes. The corpus callosum plays an important role in vision by combining the separate halves of our visual field, which process images separately in each hemisphere. It also allows us to identify the objects we see by connecting the visual cortex with the language centers of the brain. In addition, the corpus callosum transfers tactile information (processed in the parietal lobes) between the brain hemispheres to enable us to locate touch. LocationDirectionally, the corpus callosum is located underneath the cerebrum at the midline of the brain. It resides within the interhemispheric fissure, which is a deep furrow that separates the brain hemispheres. Agenesis of the Corpus CallosumAgenesis of the corpus callosum (AgCC) is a condition in which an individual is born with a partial corpus callosum or no corpus callosum at all. The corpus callosum typically develops between 12 and 20 weeks and continues to experience structural changes even into adulthood. AgCC can be caused by a number of factors including chromosome mutations, prenatal infections, exposure of the fetus to certain toxins or medications, and abnormal brain development due to cysts. Individuals with AgCC may experience cognitive developmental delays, and they may have difficulty understanding language and social cues. Other potential problems include hearing deficits, distorted head or facial features, spasms, and seizures. How are people born without a corpus callosum able to function? How are both hemispheres of their brain able to communicate?Researchers have discovered that the resting-state brain activity in both those with healthy brains and those with AgCC look essentially the same.This indicates that the brain compensates for the missing corpus callosum by rewiring itself and establishing new nerve connections between the brain hemispheres. The actual process involved in establishing this communication is still unknown.
The cerebrum is divided into two major parts: the right and left cerebral hemispheres or halves at a fissure, the deep groove down the middle. The hemispheres communicate with each other through the corpus callosum which is a bundle of fibers between the hemispheres. Each hemisphere controls muscles and glands on the opposite side of the body (i.e. the right side of the brain or hemisphere controls the left side of the body.)
Enlarge by passing over or clickingimage info This image is Copyright © My-MS.org and falls under Image License E defined under the Image License section of the Disclaimer page.The cerebral cortex is connected to various subcortical structures like the thalamus and the basal ganglia, sending information to them along efferent connections and receiving information from them via afferent connections. Most sensory information is routed to the cerebral cortex via the thalamus. Olfactory information, however, passes through the olfactory bulb to the olfactory cortex or piriform cortex. The vast majority of connections are from one area of the cortex to another rather than to subcortical areas. Cortical regions known as associative cortex are responsible for integrating multiple inputs, processing the information, and carrying out complex responses. The cortex is commonly described as comprising three parts: Sensory Areas, Motor Areas, and Association Areas. Sensory Areas are the areas that receive and process information from the senses. The parts of the cortex that receive sensory inputs from the thalamus are called primary sensory areas. The senses of vision, audition, and touch are served respectively by the primary visual cortex, primary auditory cortex and primary somatosensory cortex. In general, the two hemispheres receive information from the opposite (contralateral) side of the body. Motor Areas are located in both hemispheres of the cortex. They are shaped like a pair of headphones stretching from ear to ear. The motor areas are very closely related to the control of voluntary movements, especially fine fragmented movements performed by the hand. The right half of the motor area controls the left side of the body, and vice versa. Two areas of the cortex are commonly referred to as primary motor cortex, which executes voluntary movements, and supplementary motor areas and premotor cortex, which select voluntary movements. Association Areas function to produce a meaningful perceptual experience of the world, enable us to interact effectively, and support abstract thinking and language. The parietal, temporal, and occipital lobes - all located in the posterior part of the cortex - organize sensory information into a coherent perceptual model of our environment centered on our body image. The frontal lobe or prefrontal association complex is involved in planning actions and movement, as well as abstract thought. Our language abilities are localized to the association areas of the parietal-temporal-occipital complex, typically in the left hemisphere. Wernicke's area relates to understanding language while Broca's area relates to its use. A longitudinal fissure or division separates the brain into two distinct cerebral hemispheres, connected by the corpus callosum. The sides resemble each other and each hemisphere's structure is generally mirrored by the other side. Yet despite the strong similarities, the functions of each cortical hemisphere are
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