The Brain, Mesencephalon, Myelencephalon - Essay Example

The brain is the most complex organ inside the human body. It is the control unit of the entire body and directs all internal and external actions. The brain is divided into five major structures each of which is described below.

The Mesencephalon is located in front of the pons and in between the forebrain and the hindbrain. It is a very important part of the brain as it plays a crucial role in the proper coordination of the spinal cord and the brain in the central nervous system. It is subdivided into two regions: tectum and tegmentum. Tectum and tegmentum are the dorsal and ventral parts of the Mesencephalon respectively. The tectum is made up of a number of pairs of nuclei that have a particular function. Tectum is responsible for maintaining proper sight and hearing. This is done by controlling the amount of light that enters the eye by inducing pupil dilation. There are three very important nuclear structures present in the tegmentum. They are called the red, periaqueductal gray, and the substantia nigra. These play a major role in suppressing pain and changing physical behavior. It contains the cerebral aqueduct which makes connections between the third and fourth ventricles. Locomotion is also under the control of the Mesencephalon.

It is composed of the medulla oblongata. Since this lies in a region of the hindbrain, it acts as a mediator between the spinal cord and the brain and moderates the information transfer between the two. It lies in the most inferior part of the brainstem and hence is closest to the spinal cord among all the other structures. The Myelencephalon is responsible for controlling functions that are not consciously controlled by thought. These are called reflex actions. It connects the brain to the spinal cord and may be called an overlap of the two. Because of its proximity to the spinal cord, it integrates with it to perform various reflex actions. Vital activities like respiration and heart rate are controlled by the myelencephalon. In addition, the functions of digestion, swallowing, sneezing, and many other autonomic functions are controlled by this part of the brain.

The Telencephalon is a large structure with many grooves on its exterior side. Most of the functions are carried out in its interior in its three important structures. These are the basal ganglia, cerebral cortex, part of the hippocampus, and the olfactory bulb. Hippocampus is a C-shaped area present deep inside the telencephalon; it plays a key role in preserving old memories and creating new ones. The olfactory bulb manages the sense of smell. The Telencephalon carries out a wide range of other functions. It is largely responsible for interpreting nerve impulses from different sense organs. In addition to controlling the senses of touch and smell, it is also responsible for motor function. It has an important role in planning and coordinating responses to different stimuli. The whole of the telencephalon especially the hippocampus is also associated with ‘higher’ traits which are the person’s intelligence and personality. The control of emotions is under the control of many regions but the man activities take place in the amygdala.

Metencephalon is located just above the myelencephalon and below the cerebrum.  It contains part of an important structure called the reticular formation. These form protrusions on the side of the brain known as the pons which contain millions of nerve fibers and creates a pathway to the cerebellum. It has some role to play in the lip and tongue movement to make different sounds. It coordinates with other parts of the brain to regulate blood circulation and the overall functioning of the heart. It is largely responsible for maintaining the equilibrium of the body during movement as well as controlling the fine muscle movements in different tasks. Part of motor function is also under the control of the Metencephalon but it also acts as a responder to different sensory impulses transmitted to the brain.

The Diencephalon is composed of the thalamus, hypothalamus, epithalamus, and subthalamus. It is present within the very center of the brain and lies above the brainstem. The diencephalon is interconnected with the surrounding network of the limbic system which is responsible for the memory and emotion of a person. The Diencephalon receives the sensory impulses from the afferent neurons and filters them before relaying them to the cerebrum and cerebellum of the brain. Thalamus is the grey matter of the brain and lies in the upper part of the Diencephalon. The lowermost part of the Diencephalon is the hypothalamus. The diencephalon is filled with different ventricles all of which are filled with cerebrospinal fluid. The hypothalamus is a key part of this structure which manages the endocrine system and regulates the Central nervous system. It is also responsible for homeostasis and water regulation in the body. This part of the brain is also partially responsible for eye movement and controlling the sense of hearing.