The_Brain

The Brain PSY/240 Due 8/26/12 There are five major structures of the brain. These structures include the myelencephalon (or medulla), metencephalon, mesencephalon, diecephalon, and telencephalon. Each of these brain structures contribute to different functions in the human body. The first structure of the brain is the myelencephalon also called the medulla. The myelencephalon is the most posterior part of the brain. This structure is made up of bundles of axons called tracts that carry signals between the rest of the body and the brain. The reticular formation is also a part of the myelencephalon. The reticular formation is a complex system of 100 tiny nuclei that occupy the central core of the brain stem from the bottom extremity of the myelencephalon to the top extremity of the midbrain. Parts of the reticular formation play a role in arousal. Since there are different nuclei in the reticular formation it is involved in a variety of different functions such as sleep regulation, movement, attention, muscle tone management, and reflexes of the cardiac, circulatory, and respiratory systems. The myelencephalon structure is responsible for controlling autonomic functions such as heart rate, digestion, and breathing. The second structure of the brain is the metencephalon, like the medulla it houses parts of the reticular formation and tracts that are also located in the myelencephalon. The metencephalon is made up of two parts which are the pons and the cerebellum. The pons also consists of some of the tracts and reticular formation as in the myelencephalon. The cerebellum is a very important sensorimotor structure. The cerebellums functions also include muscle movement coordination and posture maintenance. The metecephalons functions are arousal, sleep; assist in controlling autonomic functions; such as sending sensory information between the cerebrum and cerebellum and controlling movement. For instance, if the cerebellum was damaged an individual may show cognitive and sensorimotor deficits. The next structure of the brain is the mesencephalon also known as the midbrain. The mesencephalon is located between the forebrain and the brainstem. The mesencephalon has two branches which are the tectum and the tegmentum. The tectum is located at the upper surface of the midbrain. The tectum is made up of the inferior colliculi (auditory) and the superior colliculi (visual); there have auditory and visual functions. The tegmentum contains tracts, the reticular formations, the periaqueductal gray, the substantia nigra, and the red nucleus. The substantia nigra and the red nucleus are important mechanisms of the sensorimotor system. The cerebral aqueduct is of special interest because of its role in mediating the analgesic (pain-reducing) effects of opiate drugs (Pinel, 2011). The fourth structure of the brain is the diencephalon. The diencephalon is made up of the thalamus and the hypothalamus. The thalamus is the large two lobed structures that constitute the top of the brain stem (Pinel, 2011). The masa intermedia join the double lobed thalamus. The thalamus contains many different pairs of nuclei, majority of them project to the cortex. The nuclei that are understood the most is the sensory relay nuclei. The sensory relay nuclei receive signals from sensory receptors processes them and then transmits them to the proper areas of the sensory cortex. For instance, the most important relay stations are the lateral geniculate nuclei, the ventral posterior nuclei, and the medial geniculate nuclei. These relay stations are located in the visual, auditory, and somatosensory systems, individually. They receive the message and send it to multiple places. The hypothalamus is located under the front of the thalamus. The hypothalamus role is very important; it regulates the behaviors that are motivated. For instance, some of these behaviors include eating, sleeping, and sexual behaviors. It regulates these behaviors by releasing hormones from the pituitary gland. The optic chiasm and mammillary bodies are also part of the hypothalamus. The last structure of the brain is the hugest and most complex part of the brain called the telencephalon. The telencephalon contains the cerebral cortex. The telencephalon also consists of many other structures such as the major fissures which are big grooves in a complex cortex it includes the longitudinal fissure, lateral fissure, and central fissure. It also consists of the most important gyri’s that are located in the frontal, parietal, and temporal lobes, respectively (Pinel, 2011). The gyri include the precentral gyri, the postcentral gyri, and the superior gyri which are the largest (Pinel, 2011). The cerebral commissures are also located in the telencephalon, which are hemisphere connecting tracts (Pinel, 2011); the biggest tract is the corpus callosum. The limbic system is also located in the telencephalon. The limbic system regulates behaviors that are motived and consist of major structures that surround the thalamus such as; the amygdala, the fornix, the cingulate cortex, and the septum. The basal ganglia is the last structure in the telencephalon. The basal ganglia’s function is to regulate voluntary motor responses. The basal ganglia includes structures such as the amygdala, the caudate, the putamen, and the globus pallidus. The telencephalon begins voluntary movement, interprets sensory input, and mediates complex cognitive processes such as learning speaking and problem solving (Pinel, 2011). In conclusion, the brain and the structures of the brain are very convoluted. The brain contributes to majority of our body functions if not all of our functions. There will be continuous research on the brain due to its complexity and there will always be questions left unanswered and new discoveries. I do not think that the brain will ever be fully understood because of its complexity. Reference Pinel, J. P. J. (2009). Basics of biopsychology. Boston, MA: Allyn and Bacon.