Anatomy & Organs

Corpus Callosum – structure, function & diseases

Corpus Callosum

The corpus callosum connects the hemispheres of the brain . It runs transversely and is made up of a multitude of fibers. It is also called beam .

What is the corpus callosum?

The corpus callosum is medically referred to as the commissura magna . In addition, it is also titled beam. It consists of over 200 million nerve fibers. In the cerebrum, efferent and afferent nerve fibers are distinguished.

The cerebrum is called the telencephalon. It forms the largest part of the human brain. The cerebrum is part of the central nervous system and has two hemispheres. This differentiates between the right and left hemispheres of the brain. The cerebrum is responsible for processing many thought and action processes. In it there are different web systems consisting of fibers. These are divided into three categories. These include the commissural fibers, the projection fibers and the association fibers. The projection fibers connect the basal ganglia to the brainstem .

The association fibers connect individual areas of the same hemisphere with each other. The corpus callosum forms the commissural fibers. These connect the areas of almost all parts of both hemispheres with each other. The area of ​​the primary auditory and visual cortex is excluded. The corpus callosum is responsible for ensuring that communication and information transfer between the two halves of the brain can function.

Anatomy & Structure

The corpus callosum has a curved structure and is located at the level of the temporal lobes. Seen from above, it is in the middle of the head and runs along the longitudinal cleft of the brain. It forms the roof of the two lateral ventricles. The commissural fibers contained in it are double-barreled.The corpus callosum is divided into three areas. The frontal section is the beam knee or genu. The middle section is called the bar trunk or truncus. The rear area represents the bar bulge or splenium. Below the genu, the corpus callosum runs out as a thin rostrum. The fibers that connect the two frontal lobes are called the frontal or minor forceps.

The fibers that connect both occipital lobes are the occipital forceps or forceps major. The corpus callosum connects the cortical areas with the identical tasks of the respective hemispheres. The posterior and anterior fibers of the corpus callosum are U-shaped. The back of the bar is called the dorsal surface. This is covered by a thin gray coating. It is called Indusium griseum. It is located in the cortical limbic areas.

Function & Tasks

The corpus callosum plays an important role in connecting the two halves of the brain. The commissure system located in it has the important task of transmitting information from both hemispheres. The visual information of the left visual field is processed in the right occipital lobe.

Similarly, the left occipital lobe processes the visual input from the right visual field. The corpus callosum allows both occipital lobes to exchange what is seen throughout the visual field via a secondary communication pathway. The same applies to all other receptive and motor centers in the cortex of the cerebrum. Without the corpus callosum, this exchange would not have taken place. There is a coordination of the information from the respective cerebral hemispheres. The commissural fibers of the corpus callosum are both homotopic and heterotopic. This connects the areas of the cortex symmetrically and asymmetrically. This makes possible,

This means that objects that are seen on the left side of the face or touched with the hands can only be named through the functional activity of the corpus callosum. The reason for this is that the associated sensory information is processed and interpreted in the right hemisphere of the brain. In the left hemisphere of the brain, however, the object felt is named by the language centers. The linking of the cerebral hemispheres with each other has an important meaning in the verbal-musical as well as the verbal-analytical information transmission and processing. The task of the beam goes far beyond a purely functional merging of the hemispheres.

Diseases

Lesions in the area of ​​the corpus callosum lead to defective information processing, which is received in the respective hemispheres of the brain. Objects felt or seen could not be recognized or named.The information that is taken in by the senses can no longer be fully processed and put together in the individual sensorimotor areas. This leads to life-changing changes and has a major impact on coping with everyday life.

Clinically, the corpus callosum plays an important role in conditions such as epilepsy . Before there were good drugs that are used today to treat epilepsy, the corpus callosum was surgically severed. This surgical procedure is called a callosotomy or “split-brain operation”. Today it only occurs in isolated cases in very severe forms of epilepsy.

By severing the corpus callosum, doctors want to prevent the pathogen from spreading from one hemisphere of the brain to the other. The severing of the interface between the two hemispheres is intended to prevent the disease from getting worse. In addition to diseases such as severe epilepsy, in the past the surgical intervention was often carried out after severe falls. The use of this method was also significantly reduced in these patients. Since the cognitive impairments of such an intervention are immense, the method is considered very controversial, although it has not been completely abandoned to this day.

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Hello! I am Lisa Newlon, and I am a medical writer and researcher with over 10 years of experience in the healthcare industry. I have a Master’s degree in Medicine, and my deep understanding of medical terminology, practices, and procedures has made me a trusted source of information in the medical world.