Division Of The Brain Essay

The human brain has five divisions. They start forming in the vertebrae embryo as the tissue that eventually develops into the central nervous system. The first developments of the brain are three swellings that appear at the anterior end of a fluid filled tube. These swellings eventually become the forebrain, midbrain, and hindbrain. What happens is, the forebrain swelling grows into two different swellings and so does the hindbrain swelling. This is what makes up the five divisions of the brain. These divisions are known as the telencephalon, the diencephalon, the mesencephalon, the metencephalon, and the myelencephalon. The myelencephalon, also called the medulla, is the most posterior of the divisions of the brain. It is composed mainly of tracts carrying signals
between the brain and the body. The myelencephalon is made up of about 100 tiny nuclei that occupy and central core of the brain stem.
These nuclei are responsible for a number of functions including sleeping, attention, movement, the maintenance of muscle tone, and various cardiac, circulatory, and respiratory reflexes. Damage to this part of the brain is life-threatening. The metencephalon also houses many tracts that both ascend and descend as part of a reticular formation. These structures create a bulge called the pons. The pons is one major division of the metencephalon. The other is the cerebellum. This is the large convoluted structure on the brain stem. Damage to this part of the brain makes it impossible to control one’s movements and to adapt them to changing conditions. Like the metencephalon, the mesencephalon also has two divisions. They are the tectum and the tegmentum. The tectum is the dorsal surface of the midbrain. In mammals, it is composed of two pairs of bumps called the colliculi. The posterior part is called the inferior colliculi and has an auditory function. The anterior pair is called the superior colliculi and hasa visual function. The tegmentum is the part of the mesencephalon ventral to the
tectum. It contains three structures: the periaqueductal gray, the substantia nigra, and the red nucleus. The periaqueductal gray is the gray matter situated around the cerebral aqueduct. This connects the third and fourth ventricle. The cerebral aqueduct is responsible for mediating the analgesic effects of opiate drugs. The substantia nigra and the red nucleus are responsible for parts of the sensorimotor system. The diencephalon is made up of two structures: the thalamus and the hypothalamus. The thalamus is a large structure that constitutes the top of the brain stem. It is made up of two lobes. One lobe sits on each side of the third ventricle and the two lobes are joined by the massa intermedia. The thalamus is comprised of many different pairs of nuclei. Several of these nuclei are sensory relay nuclei. These receive signals sent by the sensory receptors, process them, and then transmit them to other areas of the sensory cortex. The lateral geniculate nuclei are the visual sensory relay nuclei. The hypothalamus is located below the thalamus. It is responsible for regulating several motivated behaviors. It does this by releasing hormones from the pituitary gland. My girlfriend’s younger sister had a tumor on her pituitary gland that was removed two years ago. She now has to give herself growth hormone injections in order to grow. She is very small for her age and will remain that way her whole life. Because of the removal of the tumor, she has developed a number of health problems. In addition to the pituitary gland, there are two other structures: the optic chiasm and the mammillary bodies. The optic chiasm is where the optic nerves come together from each eye. The mammillary bodies are a pair of spherical nuclei located on the inferior surface of the hypothalamus. The telencephalon is the largest division of the brain. It mediates the brain’s most complex functions. The cerebral cortex is deeply convoluted. The two major parts on the lateral surface of each hemisphere of the brain are the central fissure and the lateral fissure. These two fissures help to divide each hemisphere into four lobes, the frontal lobe, the parietal lobe, the temporal lobe, and the occipital lobe. The limbic system is a circuit system that goes around the thalamus. It is responsible for motivated behaviors such as fleeing, feeding, fighting, and sexual behavior. Another feature of this part of the brain is the basal ganglia. This is a group of subcortical structures that are responsible for voluntary movement. Damage to these structures results in motor disorders like Parkinson’s disease. Together, all five divisions of the brain work to keep the body functioning correctly. Now that we have identified which parts of the brain control what, we can determine the causes and cures for a lot of problems. The more we understand how the brain works, the closer we get to finding solutions for problems like Alzheimer’s disease and cancer.