The Fontal Lobes Anatomy and its Connections with Other Parts of the Nervous System - Research Paper Example

Frontal Lobe Introduction Brain is known to be the control centre of the bodily functions and activities of a human being. It is designed in such a way that impulses pass in the brain through neurons through which specific set of actions are carried out again with the help of impulses. The structural and the functional unit of the brain stem is neuron. Neurons can be defined as the excitable nerve cells and their components which transmit signals through their synapses. It consists of a cell body which is known as the perikaryon and the processes. The processes which are present in a neuron are axons and dendrites. The dendrites and axons function specifically to transmit the nerve impulses in the body. The dendrites particularly receive the impulses and they convey the impulses to the neuron whereas the axon carries the impulse away from the neuron to its respective destination. The human brain is divided into two hemispheres, and within each hemisphere there are four lobes namely; frontal lobe, parietal lobe, temporal lobe and occipital lobe (Goldberg & Sacks 2001; Snell 2006). Overview of Frontal lobe Frontal lobe lies in front of the cerebral hemisphere. Cerebral hemisphere is divided by four sulci which are the central sulcus, lateral sulcus, parieto-occipital sulcus and calcarine sulcus. Frontal lobe lies anteriorly to the central sulcus and superiorly to the lateral sulcus. The frontal lobe helps in the motor functions of the body along with cognitive functions. An area known as pre central area is located in frontal lobe which receives connections from the somatosensory area of parietal lobe. This area helps in the initiation of motor functions. Broca’s area is also located in the frontal lobe which helps in the speech function of individuals. The frontal lobe is also known to help in the cognitive processes of thought and learning. Personality is also determined because of the areas which are located in the frontal lobe. It is connected to other parts of the brain through association fibres which are discussed subsequently. Many other areas like supplementary motor area, frontal eye field and prefrontal cortex are located in the region of frontal lobe (Waxman 2009; Carlson & Carlson 2010). Anatomy of Frontal lobe Frontal lobe is located at the front of each cerebral hemisphere. The superiolateral surface of the frontal lobe has three sulci which divide it into four gyri. Gyri are the folds of the brain which increase the surface area of brain and the folds are separated from each other by sulci. In frontal lobe a sulcus goes parallel to the central sulcus called precentral sulcus and precentral gyrus lies between them. Extending anteriorly from the precentral gyrus we find superior and inferior frontal sulci. The superior frontal gyrus lies superior to the superior frontal sulcus and between the two superior and inferior frontal sulci the middle frontal gyrus is present. Inferiorly to the inferior frontal sulcus is the inferior frontal gyrus. Histologically it can be seen that the precentral area of frontal lobe does not have granular layers but rather has pyramidal nerve cells. These pyramidal cells get concentrated in the area of precentral gyrus and paracentral lobule. The pyramidal cells concentrated in this region are known as the cells of Betz. The small pyramidal cells in the region of precentral area also gives rise to corticospinal and corticobulbar fibres. The pyramidal cells of Betz also give rise to corticospinal and corticobulbar fibers but in comparison to the small cells they are quite less in number.The precentral area is then divided into two regions namely anterior and posterior. The posterior region is known as the motor area which is located in the Broadman’s area 4. The primary motor cortex also gives origin to corticonuclear and corticospinal fibres. This posterior region is found in the precentral gyrus. The anterior region of the precentral area is known as the premotor area and is said to be in the Broadman area 8,44 and 45. Frontal eye field is also located in the precentral area of the frontal lobe. It extends from the area allocated to face to the middle frontal areas. Stimulation of the frontal eye field causes the movement of eyes to the opposite side (Snell 2006; Augustine 2008; Waxman 2009). Functions of Frontal Lobe The primary motor area located in the precentral area is known to produce movements in the body. If the primary motor area of one side is stimulated the muscles on the opposite side of the body are known to contract. Bilateral movements of extraocular muscles along with the muscles of face and tongue are known to occur. The primary motor area has specific points for the muscles of the body in an inverted form i.e. the lowest part of the motor area has the point for face, jaw and eye muscles. The main function of primary motor area is to help in the movement of muscles in different parts of the body. The secondary motor area on the other hand is also responsible for muscle movements but with a high degree of stimulation in comparison to the primary motor area. A supplementary motor area is also located in the frontal lobe right in the medial frontal gyrus. Stimulation of the supplementary motor area helps in the contralateral movement of limbs. The motor speech area of Broca is also located in frontal lobe in the inferior frontal gyrus. Broca’s area is discussed subsequently. The prefrontal cortex is an area anterior to the precentral area. It helps in determining the judgement of the individuals. (Goldberg & Sacks 2001; Snell 2006). Broca’s area is a region of the brain located in the inferior frontal gyrus represented in Broadman’s map as area 44 and area 45. The functions of the broca’s area are related to the production of speech and regulation of the sequence of the sound. Fresh evidence showed that not only the language production is done by Broca’s area but it also plays an important role in language comprehension. Neuroimaging studies showed the participation of the Broca’s area in processing a complex sentence. The Broca’s area also helps in understanding action of others (Kleinman et al 2008; Moro et al 2000). Aphasia is an impairment of the skills related to language which is caused by damage to the brain. The Broca’s aphasia means the aphasia caused by the damage to the Broca’s area. Patients suffering from Broca’s aphasia show agramatism which is a pathological inability to use words in grammatical order. Patients have difficulty in initiation of speech and are nonfluent. A Broca’s aphasic patient misinterprets as they switch parts of speech. The causes of the Broca’s aphasia include stroke, trauma to brain, tumor, cerebral hemorrhage and etc (Moro et al 2000). Connections of Frontal lobe The frontal lobe is interconnected with other parts of the autonomic nervous system through many association fibres. These association fibres can be divided into long association fibres or short association fibres. The short association fibres are involved in connecting the gyri to each other. The long association fibres form bundles which connect different lobes together or with other systems of the brain. The uncinate fasiculus is a bundle extending from the inferior surface of the frontal lobe to the pole of the temporal lobe. It helps in connecting the first motor area of frontal lobe to the parietal lobe. The cingulum is a white matter fasiculus which connects both the frontal and parietal lobes parahippocampal regions. The arcuate fasiculus extends from the frontal lobe to the temporal lobe and the occipito-frontalis fasiculus extends from the occipital lobe to the frontal lobe. The superior longitudinal fasiculus is the largest bundle of fibres connecting frontal lobe to both the occipital and temporal lobes. The areas in the frontal lobe area also connected to other parts of the brain. The primary motor area has a diffuse supply of fibers from premotor area, sensory cortex, thalamus and cerebellum. The secondary motor area on the other hand receives fibres from sensory cortex, thalamus and basal nuclei. The speech area of Broca is connected to primary motor area. The prefrontal cortex is connected to many areas of cerebral cortex, thalamus and hypothalamus through different pathways. Frontopontine fibers are an example of some fibres which are connecting the prefrontal cortex to the cerebellum (Snell 2006; Carlson & Carlson 2010; Miller & Cummings 1999). Conclusion Frontal lobe is located anteriorly to the central sulcus and plays a major role in the functions of the body. It not only helps in motor movements but also helps in the cognitive functions of the body. It has important areas which have been mentioned above such as prefrontal area, motor speech area and frontal eye field. The frontal lobes work as our emotional control center. Frontal lobes help in solving a problem and give us the power to judge. Frontal lobe is involved in choosing good and bad deeds and also help in determining the resemblance and variations between things. Saving long term memories is also an important function of frontal lobe of the brain. Social and sexual behaviors are controlled by the frontal lobes too. Broca’s area of speech are present in frontal lobes which help in speech and language. The Broca’s area also help to determine as to which hemisphere of the individual is dominant. Frontal lobe disorders are commonly seen in old age people which leads to schizophrenia. Moreover damage to the areas of the frontal lobe can cause severe impairment of the motor functions of the body. It can be said that frontal lobe is one of the most important component of the brain which is needed for several functions of the body (Carlson & Carlson 2010; Bosman & Greyling 2006; Snell 2006). Bibliography Augustine, J. R. (2008). Human neuroanatomy. London: Academic. Bosman, M. C., & Greyling, L. M. (2006). Neuroanatomy. Pretoria, RSA: University of Pretoria. Carlson, N. R., & Carlson, N. R. (2010). Foundations of behavioral neuroscience. Harlow: Pearson Education. Goldberg, E., & Sacks, O. (2001). The executive brain: Frontal lobes and the civilized mind. Oxford [u.a.: Oxford Univ. Press. Miller, B. L., & Cummings, J. L. (1999). The human frontal lobes: Functions and disorders. New York: Guilford Press. Moro, A., Perani, D., Piattelli-Palmarini, M., & Cappa, S. F. (January 01, 2000). Broca's aphasia, Broca's area, and syntax: A complex relationship. Behavioral and Brain Sciences, 23, 1, 27-28. Kleinman, J. T., Newhart, M., Gingis, L., Pawlak, M., Hillis, A. E., & Davis, C. (April 01, 2008). Speech and language functions that require a functioning Broca's area. Brain and Language, 105, 1, 50-58. Snell, R. S., & Snell, R. S. (2006). Clinical neuroanatomy. Philadelphia: Lippincott Williams & Wilkins. Top of Form Bottom of Form Top of Form Top of Form Bottom of Form Top of Form Top of Form Waxman, S. G. (2009). Clinical neuroanatomy. New York: McGraw-Hill Medical.Top of Form Bottom of Form Bottom of Form Bottom of Form Bottom of Form Read More