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Introduction
The brain is that part of the central nervous system positioned in the skull. It is a mass of tissue pinkish-gray in color consisting of a network of nerve cells and weighs approximately three pounds. The human brain is one of the major and important organs of the body. It acts as a control center for all the vital activities of the body from controlling our emotions to managing our movements. Furthermore, the brain being a complex organ, it receives, interprets and directs sensory information all over the body (Bancroft, 1998).
The brain has three major divisions, the forebrain, the midbrain and the hindbrain. The three divisions are sub divided into five major parts. These parts include the myelencephalon the part of the brain next to the spinal cord, the mesencephalon, diencephalon and telencephalon, the outermost part from the spinal cord.
Fore Brain
This part of the brain consists of the telencephalon and diencephalon. It is the most complex part of the three, usually responsible for receiving, processing sensory information and in control of motor function.
Telencephalon
Its primary structures are the limbic system, basal ganglia and the cerebral cortex. The cerebral cortex encloses the cerebral hemispheres (the left and right hemispheres). It is the folded, convoluted tissue that contains a massive amount of small and large furrows (fissures) and swellings (the gyri). These structures greatly increase the general surface area of the cortex. The cerebral cortex is usually known as the gray matter, this is due to the large number of cells which appear grayish brown. The differences between men and women both psychologically and emotionally are as a result of the functions of left and right hemispheres. However, the left hemisphere is believed to be the dominant half of the brain due to its better chronological, analytic and language abilities (Bancroft, 1998).
The left hemisphere controls the right half of the body, intellectual ability and communication. The right hemisphere is related to unconscious awareness which involves the awareness of faces and patterns, perceptive reasoning, knowledge of body language and social signs, processing of images, innovation, insight and holistic understanding. Communication involving the left and right hemispheres takes place through the corpus callosum, which is more fully developed in women than men, this likely give rise to the womens sixth sense (Bancroft, 1998).
The surface of the left and right hemispheres is divided into four lobes, namely, the temporal lobe, frontal lobe, occipital lobe and the parietal lobe. In addition is the insula a fifth lobe which is an internal lobe not visible from the brain surface. Their absence can result to a person being emotionally low, droopy, and not sensitive to social standards. Furthermore, the frontal lobe controls the functions of the hypothalamus, therefore controlling how the endocrine and autonomic nervous systems function. Within the frontal lobe is the main motor cortex which control body movement. The rest of the lobes have a role in perception. The basal ganglia are a set of sub cortical nuclei found underneath the anterior parts of the lateral ventricles; they control the body movement. Some anatomists regard the amygdala which is a primary component of the limbic system as a part of the basal ganglia due to its position. The limbic system is a compilation of brain structures which are involved in control of emotions, all-around behavior, and memory (Bailey, 2000).
Diencephalon
This is the second major division of the forebrain. The main structures of diencephalon are the thalamus and hypothalamus. The thalamus acts as a central point for receiving sensory signals and linking motor signals going through the cerebral cortex. It consists of two large linked lobes, the Massa intermedia act as a bridge between the two lobes of the thalamus. The hypothalamus has numerous nuclei which control the fundamental survival actions and activities of the body. In addition, the hypothalamus controls the autonomic nervous system and endocrine system and it governs the posterior pituitary gland hormones.
Midbrain
This part is also referred to as the mesencephalon.
Mesencephalon
It consists two parts, namely, the tectum and tegmentum. The superior colliculi and the inferior colliculi form the basic structure of the tectum and they form part of the body visual system and the auditory system. Their role in mammals is related to visual reflexes. The tegmentum is found beneath the tectum. It is composed of the periaqueductal gray matter, red nucleus, substantia nigra and the reticular formation.
The reticular formation has numerous nuclei and a network of neurons positioned at the centre of the brain. Its function is to receive sensory information and co-ordinate a persons attention, muscle movement and various fundamental reflexes. The periaqueductal gray matter is composed of neural circuits whose function is to control a series of movements involving the typical behavior of species. The substantia nigra and the red nucleus are components of the motor system. The red nucleus help in transfer of motor information from the brain to the spinal cord and the substantia nigra influences the caudate nucleus through dopamine-secreting neurons (Bailey, 2000).
The Hindbrain
The hindbrain is the lower part of the brainstem and is composed of the metencephalon and the myelencephalon.
Metencephalon
This comprises of the cerebellum and pons. The cerebellum is involved in control and co-ordination of both voluntary and involuntary bodily movements such as hand-eye co-ordination (Bailey, 2000). The pons is a large swelling in the brain stem between the mesencephalon and the myelencephalon. They consist of a part of the reticular formation and nuclei known to be important in the function of sleep and awakening.
Myelencephalon
The myelencephalon contains the medulla oblongata an oblong marrow. It consists of nuclei which control critical bodily functions. The medulla oblongata controls involuntary functions of the cardiac, digestion and the respiratory systems. Reflex activities such as vomiting are controlled by the medulla oblongata. Myelencephalon is adjacent to the spinal cord and if damaged can result to a sudden death (Bancroft, 1998).
Conclusion
The brain is responsible for the major functions of the body and it acts as a control point. The five structures which have various functions amount to the brain performance.
Reference list
Bailey. (2000) Anatomy of the Brain.
Bancroft. (1998) Brain Physiology. Web.
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