Amyotrophic Lateral Sclerosis

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The plan for any movement originates in the brain. The major part of the brain involved in the initiation and control of voluntary movement is the primary motor cortex. Motor neurons in the brain are called upper motor neurons (UMNs), whereas motor neurons in the brain stem and spinal cord are called lower motor neurons (LMNs). UMNs are unable to leave the CNS; therefore they must synapse with LMNs whose axons can leave the CNS, which allows them to synapse with muscles throughout the body. Thus, in a normal situation, messages from UMNs are transferred to LMNs, and from there are transferred to specific muscles. UMNs and LMNs are responsible for movements such as walking and chewing, and movement of the arms, legs, chest, and face, respectively. This permits healthy individuals the ability to voluntarily move their muscles with ease. Amyotrophic Lateral Sclerosis is also referred to as a motor neuron disorder (MND), as it is characterized by the continual degeneration of upper and lower motor neurons. These motor neurons, as previously stated, are responsible for voluntary muscles in the body, and as the neurons degenerate, or die, the neurons are unable to send messages to the muscles. When muscles can no longer receive signals, they become unable to function, and in turn, weaken and waste away. Eventually, the brain loses its ability to start and control voluntary movement, resulting in paralysis. Since ALS only affects the voluntary motor neurons, the senses (seeing, smelling, tasting, hearing, and tactile sensations) are spared. The involuntary motor neurons are also not affected (for example, the heart and digestive system). Additionally, the individual is often not affected cognitively. ... ... middle of paper ... ...icles Mitchell, J. D. and G. D. Borasio. 2007. Amyotrophic lateral sclerosis. Seminar. 369: 2031- 2041. Roth-Kauffman, M., and J. Niebauer. 2012. Amyotrophic lateral sclerosis: Diagnostic and appropriate management. Clinician Reviews. 22(7): 15-21 Rowland, L. P., and N. A. Shneider. 2001. Amyotrophic lateral sclerosis. New England Journal of Medicine. 344(22): 1688-1700. Wijesekera, L. C. and P. N. Leigh. 2009. Amyotrophic lateral sclerosis. Orphanet Journal of Rare Diseases. 4(3): doi:10.1186/1750-1172-4-3. Webpages ALS Association. About ALS. Updated 2010. Accessed March 13, 2014. National Institute of Neurological Disorders and Stroke. NINDS Amyotrophic Lateral Sclerosis (ALS) Information Page. Updated February 4, 2014. Accessed March 13, 2013.

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