Part Of The Brain And Their Functions

Part Of The Brain And Their Functions – Nearly 100 billion neurons make up the adult brain, which can be divided into the cerebrum (with two cerebral hemispheres), the diencephalon, the brainstem (which includes the midbrain, pons, and medulla oblongata), and the cerebellum.

Nearly 100 billion neurons make up the adult brain, which can be divided into the cerebrum (with two cerebral hemispheres), the diencephalon, the brainstem (which includes the midbrain, pons, and medulla), and the cerebellum (FIGURE 12-1). The largest part (cerebrum) coordinates sensory and motor functions and higher mental functions such as memory and reasoning. The diencephalon processes additional sensory information. The neural pathways of the brainstem connect the components of the nervous system and regulate certain visceral activities. The cerebellum coordinates voluntary muscle movements.

Part Of The Brain And Their Functions

Part Of The Brain And Their Functions

The brain is basically designed as a central cavity surrounded first by gray matter and then by white matter. The gray matter (cortex) mainly consists of neuronal cells, while the white matter consists of myelinated fibers. This pattern is different in the spinal cord, where the gray matter is in the center and the white matter on the outside. However, the brain also has additional regions of gray matter that are not found in the spinal cord. The cerebral hemispheres and the cerebellum have an outer cortex, which is a layer of gray matter. Male brains are usually larger compared to female brains.

Functional Areas Brain Stock Photos

Interconnected cavities known as ventricles exist within the cerebral hemispheres and brainstem. They are continuous with the central canal of the spinal cord and also contain cerebrospinal fluid. The walls of the hollow ventricular chambers are lined with ependymal cells. Two large lateral ventricles are located within the frontal, temporal and occipital lobes. The third ventricle is below the corpus callosum in the midline of the brain. The fourth ventricle is located in the brainstem and is connected to the third ventricle by a narrow cerebral aqueduct.

Within each cerebral hemisphere are large C-shaped chambers known as the paired lateral ventricles. They demonstrate a pattern of cerebral growth and lie close together in front of each other. They are separated by a thin middle membrane called the septum pellucidum. Each lateral ventricle is connected to a thin third ventricle, which is surrounded by the diencephalon through a channel known as the interventricular foramen. The third ventricle is connected to the fourth ventricle via the cerebral aqueduct, which passes through the midbrain. FIGURE 12-2 shows the ventricles in the brain.

The cerebrum is divided into two large cerebral hemispheres, one left and one right. They make up the superior part of the brain and are easily visualized, accounting for approximately 83% of the total mass of the brain. The corpus callosum is a deep bridge of nerve fibers that connects the hemispheres, separated by a layer of dura mater. It lies above the lateral ventricles, deep within the longitudinal fissure. The surface of the cerebrum is covered with convolutions, which are separated by shallow or deep grooves. Each shallow groove is called a sulcus, and each deep groove is called a fissure. Fissures separate large regions of the brain. All of these grooves form different patterns in the normal brain, with gyri and furrows being more prominent.

Several sulci divide each hemisphere into frontal, parietal, temporal, and occipital lobes (as well as a structure called the insula). The insula is a lobe of the brain, but it is buried deep within the lateral sulcus forming part of the floor of the brain. The lobes of the cerebral hemispheres refer to the bones of the skull near which they are located. The cerebral hemispheres are separated by the median longitudinal fissure, while the transverse cerebral fissure separates the cerebral hemispheres from the cerebellum below them. The lateral sulcus separates the temporal lobe from the frontal lobe.

Human Brain: Facts, Functions & Anatomy

The three basic regions of each cerebral hemisphere are the cerebral cortex, the white matter, and the basal ganglia. The cerebral cortex is the superficial gray matter and actually appears gray in fresh brain tissue. The white matter is more internal, and the basal nuclei are islands of gray matter located deep within the white matter.

The cerebral cortex, a thin layer of gray matter that forms the outer part of the cerebrum, is the center of the conscious mind. The brain of an adult contains almost 98% of all neuronal cells of the nervous system. The cerebral cortex is involved in awareness, communication, sensation, memory, understanding and initiation of voluntary movements. Its gray matter contains dendrites, neuronal cell bodies, glia and blood vessels. It lacks a fiber tract, but contains six layers containing billions of neurons. The cerebral cortex is approximately 2-4 mm thick, but makes up about 40% of the total brain mass. Its surface is almost tripled by numerous bends.

Beneath the cortex of the cerebrum is the white matter, which encompasses most of the cerebrum. It contains myelinated bundles of axons, some of which cross from one hemisphere of the brain to the other. Others carry impulses from the cortex to the nerve centers of the brain and spinal cord (FIGURES 12-3 and 12-4).

Part Of The Brain And Their Functions

In most people, one side of their cerebrum acts as the dominant hemisphere, controlling the use and understanding of language. The left side of the cerebrum is usually responsible for activities such as speaking, writing, reading and complex intellectual functions. The non-dominant hemisphere controls non-verbal functions and intuitive and emotional thoughts. The dominant hemisphere controls the motor cortex of the non-dominant hemisphere.

The Human Brain 101

In addition to sensory and motor control, memory and reasoning, the cerebrum also coordinates intelligence and personality. It is the “executive package” of the body. Functions overlap between regions of the cerebral cortex. The three functional areas of the cerebral cortex are the motor, sensory, and association areas (FIGURE 12-5). All neurons in the cerebral cortex are interneurons. Each hemisphere of the brain controls the motor and sensory functions of the contralateral (opposite) side of the body. The hemispheres are not completely equal in function, although their structure closely matches. Cortical functions are specialized, as demonstrated by a phenomenon known as lateralization. No functional area acts in isolation and conscious actions use the entire cortex in different ways.

Most of the motor areas of the cerebral cortex are located in the frontal lobes and are further defined as the primary motor cortex, premotor cortex, Broca’s area, and the frontal eye field. Impulses from large pyramidal cells in motor areas travel through the brainstem to the spinal cord via corticospinal tracts that form synapses with lower motor neurons. Their axons leave the spinal cord, reaching skeletal muscle fibers.

The primary motor cortex is also known as the somatic motor cortex. It is located in the precentral gyrus of the frontal lobe of both hemispheres. The mapping of the body’s CNS structures is called somatotopy. The premotor cortex lies just in front of the precentral gyrus in the frontal lobe and helps plan movements. Broca’s area is located in front of the lower region of the premotor area and is more represented in the left hemisphere. It has a motor speech area and also becomes active just before speech or when planning other voluntary motor activities. The anterior eye field is superior to Broca’s area, located partially within and anterior to the premotor cortex. Controls voluntary eye movements. The central sulcus separates the primary motor areas from the somatosensory areas.

Sensory areas of the cerebrum interpret impulses such as sensations on the skin, which are picked up in the anterior parts of the parietal lobes. The posterior occipital lobes affect vision, while the temporal lobes affect hearing. Taste and smell receptors are located deeper within the cerebrum. Sensory fibers also cross in a similar way to motor fibers. Additional sensory areas include the insular and occipital lobes.

Brain Anatomy And Function

The primary somatosensory cortex lies in the postcentral gyrus of the parietal lobe. It is located just behind the primary motor cortex and its neurons receive input from the somatic sensory receptors of the skin. It also receives information from position sense receptors in the joints, skeletal muscles and tendons. The somatosensory association cortex is located immediately behind the primary somatosensory cortex, is interconnected, and functions primarily to integrate temperature, pressure, and related information. The primary visual cortex, also called the striate cortex, is not only largely buried in the calcarine sulcus of the occipital lobe, but also extends to the posteriormost occipital peak. It is the largest cortical sensory area that receives visual information from the retina of the eye. The field of visual associations uses past visual experiences to interpret colors, shapes, movements, and other visual stimuli.

Each primary auditory cortex lies at the upper edge of the temporal lobe and receives impulses from the inner ear, interpreting location, loudness, and pitch. Posteriorly, the auditory association area perceives sound stimuli such as speech, music and environmental noises. The vestibular (balance) cortex controls balance and is located in the posterior insula and nearby parietal cortex. The primary (olfactory) olfactory cortex is present on the medial temporal lobe in the area of ​​the piriform lobe, which is indicated by its uncus, a hooked structure. The olfactory cortex is part of the rhinencephalon, a primitive structure that includes the orbitofrontal cortex,

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