lower motor neurons

下位運動ニューロン

WordNet

1. unrefined in character; "low comedy"
2. an air mass of lower pressure; often brings precipitation; "a low moved in over night bringing sleet and snow" (同)depression
3. a low level or position or degree; "the stock market fell to a new low"
4. used of sounds and voices; low in pitch or frequency (同)low-pitched
5. very low in volume; "a low murmur"; "the low-toned murmur of the surf" (同)low-toned
6. in a low position; near the ground; "the branches hung low"
7. less than normal in degree or intensity or amount; "low prices"; "the reservoir is low"
8. literal meanings; being at or having a relatively small elevation or upward extension; "low ceilings"; "low clouds"; "low hills"; "the sun is low"; "low furniture"; "a low bow"
9. move something or somebody to a lower position; "take down the vase from the shelf" (同)take_down, let down, get_down, bring_down
10. cause to drop or sink; "The lack of rain had depressed the water level in the reservoir" (同)depress
11. set lower; "lower a rating"; "lower expectations" (同)lour
12. machine that converts other forms of energy into mechanical energy and so imparts motion
13. a nonspecific agent that imparts motion; "happiness is the aim of all men and the motor of all action"
14. the act of causing something to move to a lower level (同)letting down
15. the act of causing to become less
16. the act of driving an automobile

PrepTutorEJDIC

1. (高さ・位置が)『低い』,低い所にある / (価格・数量・程度などが)『低い』,少ない / (身分・地位などが)『低い』,卑しい / (人格・行為などが)『卑しい』,下劣な,下品な / 《補語にのみ用いて》(体が)『弱った』;元気のない,憂うつな / (供給が)不十分な;(…が)乏しい《+『in』(『on』)+『名』》 / (音・声が)低い,小さい / (生物が)下等な / 『低く』,低い所に / (価格・程度などが)『安く』,低く / 低い声(調子)で;静かに / 最低点,最低水準
2. (牛の)モーという鳴き声 / (牛が)モーと鳴く
3. (lowの比較級)『もっと低い』,(価格が)もっと安い / 《名詞の前にのみ用いて》『下級の』;低い(下の)ほうの / …‘を'『下げる』,降ろす / 〈価格・程度・量・調子など〉‘を'『下げる』,小さくする,低下させる / 〈人〉‘を'品位(品格)を落とす / 低くなる,下がる,滅る
4. (…に向かって)顔をしかめる,まゆをひそめる《+『at(on, upon)』+『名』》 / 〈空模様が〉険悪になる,〈雨などが〉降りそうな / しかめっつら / 険悪な空模様
5. (電気の)『モーター』,電動機 / エンジン,(特に)内燃機関 / 《英》自動車(motorcar) / 《名詞の前にのみ用いて》 / モーターの;エンジンの;自動車の / モーター(エンジン)による,自動車による / (神経・筋肉について)運動の / 自動車で行く / …‘を'自動車で運ぶ
6. 低くする,低下させる;堕落させる
7. (空模様が)険悪な,荒れ模様の / しかめっつらの,(顔つきが)不機嫌な
8. 自動車運転〈技術〉,ドライブ

Wikipedia preview

出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2015/08/15 11:48:44」(JST)

wiki en

[Wiki en表示]

Lower motor neurons (LMNs) are motor neurons located in either the anterior grey column, anterior nerve roots (spinal lower motor neurons) or the cranial nerve nuclei of the brainstem and cranial nerves with motor function (cranial nerve lower motor neurons). All voluntary movement relies on spinal lower motor neurons, which innervate skeletal muscle fibers and act as a link between upper motor neurons and muscles. Cranial nerve lower motor neurons control movements of the eyes and tongue, and contribute to chewing, swallowing and vocalization. Damage to the lower motor neuron can lead to flaccid paralysis.

Classification

Lower motor neurons are classified based on the type of muscle fiber they innervate:

• Alpha motor neurons (α-MNs) innervate extrafusal muscle fibers, the most numerous type of muscle fiber and the one involved in muscle contraction.
• Beta motor neurons (β-MNs) innervate intrafusal fibers of muscle spindles with collaterals to extrafusal fibers (type of slow twitch fibers).
• Gamma motor neurons (γ-MNs) innervate intrafusal muscle fibers, which together with sensory afferents compose muscle spindles. These are part of the system for sensing body position (proprioception).

Physiology

Glutamate released from the upper motor neurons triggers depolarization in the lower motor neurons in the anterior grey column, which in turn causes an action potential to propagate the length of the axon to the neuromuscular junction where acetylcholine is released to carry the signal across the synaptic cleft to the postsynaptic receptors of the muscle cell membrane, signaling the muscle to contract.

Consequences of lesions

Damage to lower motor neurons, lower motor neuron lesions (LMNL) cause muscle atrophy, decreased strength and decreased reflexes in affected areas. These findings are in contrast to findings in upper motor neuron lesions. LMNL is indicated by abnormal EMG potentials, fasciculations, paralysis, weakening of muscles, and neurogenic atrophy of skeletal muscle. Bell's Palsy, Bulbar palsy, Poliomyelitis and Amyotrophic lateral sclerosis (ALS) are all pathologies associated with lower motor neuron dysfunction.

See also

• Upper motor neuron
• Upper motor neuron lesion
• Lower motor neuron lesion

References

Motor system

UpToDate Contents

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• 1. 筋萎縮性側索硬化症およびその他の運動ニューロン疾患の臨床的特徴clinical features of amyotrophic lateral sclerosis and other forms of motor neuron disease [show details]
  …and/or lower motor neurons . ALS is the most common form of motor neuron disease and includes upper and lower motor neuron pathology. Progressive muscular atrophy is a progressive lower motor neuron disorder …
• 2. 成人における詳細な神経学的検査the detailed neurologic examination in adults [show details]
  …muscles of the palate, pharynx, or larynx indicates a peripheral lesion (ie, at the level of lower motor neuron, neuromuscular junction, or muscle). These muscles are innervated by fibers that originate …
• 3. 筋萎縮性側索硬化症およびその他の運動ニューロン疾患の診断diagnosis of amyotrophic lateral sclerosis and other forms of motor neuron disease [show details]
  …upper and/or lower motor neurons. ALS is the most common form of acquired motor neuron disease. Clinical manifestations of ALS include the presence of upper motor neuron and lower motor neuron signs, progression …
• 4. 脊髄放射線照射の合併症complications of spinal cord irradiation [show details]
  … equina. Pathologic changes suggest a vasculopathy of proximal spinal roots with preservation of lower motor neurons within the spinal cord. Many patients remain ambulatory for many years, although weakness continues…
• 5. 多巣性運動ニューロパチーmultifocal motor neuropathy [show details]
  …The typical clinical presentation of MMN is one of subacute onset with asymmetric weakness . Lower motor neuron signs often present in a bibrachial pattern, producing arm and hand weakness without associated …

English Journal

• Relationship between dopamine deficit and the expression of depressive behavior resulted from alteration of serotonin system.

• Lee M1, Ryu YH1, Cho WG2, Kang YW2, Lee SJ2, Jeon TJ1, Lyoo CH3, Kim CH4,5, Kim DG4,5, Lee K6, Choi TH6, Choi JY1.
• Synapse (New York, N.Y.).Synapse.2015 Sep;69(9):453-60. doi: 10.1002/syn.21834.
• Depression frequently accompanies in Parkinson's disease (PD). Previous research suggested that dopamine (DA) and serotonin systems are closely linked with depression in PD. However, comprehensive studies about the relationship between these two neurotransmitter systems are limited. Therefore, the p
• PMID 26089169

• Clinical indicators of paraplegia underplay universal spinal cord neuronal injury from transient aortic occlusion.

• Bell MT1, Puskas F2, Bennett DT3, Cleveland JC Jr3, Herson PS2, Mares JM3, Meng X4, Weyant MJ3, Fullerton DA3, Brett Reece T3.
• Brain research.Brain Res.2015 Aug 27;1618:55-60. doi: 10.1016/j.brainres.2015.04.053. Epub 2015 May 22.
• Paraplegia following complex aortic intervention relies on crude evaluation of lower extremity strength such as whether the patient can lift their legs or flex the ankle. Little attention has been given to the possible long-term neurologic sequelae following these procedures in patients appearing fu
• PMID 26005132

• ALS-Linked P56S-VAPB Mutation Impairs the Formation of Multinuclear Myotube in C2C12 Cells.

• Tokutake Y1, Yamada K2, Ohata M3, Obayashi Y4, Tsuchiya M5, Yonekura S6,7,8.
• International journal of molecular sciences.Int J Mol Sci.2015 Aug 10;16(8):18628-41. doi: 10.3390/ijms160818628.
• Amyotrophic lateral sclerosis (ALS) is a rapidly progressive neurodegenerative disorder that affects upper and lower motor neurons. Since motor neurons target skeletal muscles, the maintenance system of muscles is disturbed in ALS; however, the mechanism by which this occurs is unknown. In the prese
• PMID 26266407

Japanese Journal

• Identification of plasma microRNAs as a biomarker of sporadic Amyotrophic Lateral Sclerosis

• Molecular brain 8, 67, 2015-10-25
• NAID 120005674075

• 神経再生リハビリテーション医療と神経筋病理学

• The Japanese Journal of Rehabilitation Medicine 52(12), 760-768, 2015
• NAID 130005114624

• Postnatal Development of the Corticospinal Tract in the Reeler Mouse

• The Kobe journal of the medical sciences 61(3), 71-81, 2015
• NAID 120005677779

Related Links

• The Lower Motor Neuron Syndrome - Neuroscience - NCBI ...

The symptoms that arise from damage to the lower motor neurons of the brainstem and spinal cord are referred to as the “lower motor neuron syndrome.” In clinical neurology, this constellation of problems must be distinguished from ...

• Motor Neuron Diseases Fact Sheet

What are motor neuron diseases? The motor neuron diseases (MNDs) are a group of progressive neurological disorders that destroy motor neurons, the cells that control essential voluntary muscle activity such as ...

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関連記事	「lower」「low」「motor」「lowering」「neuro」

「lower」

　　[★]

• adj.

• (low比較級)より低い、下位の、下等な、低次の、低下させる、低減させる

関

decline、decrease、depression、drop、fall、inferio、inferior、inferiorly、low level、lower dimension、lower level、lower order、lowering、reduction

　 　 　 　 　

「low」

　　[★]

• adj.

• (比較級lower-最上級lowest)低い、不十分な

関

deficient、inadequate、insufficiency、insufficient、insufficiently、poorly、scanty

　 　 　 　 　 　 　 　 　 　

「motor」

　　[★]

• adj.

• 運動の

• n.

• モーター

関

exercise、kinesis、locomote、locomotive、motility、motion、move、movement

　 　 　

「lowering」

　　[★]

• n.

• 低下、低減

関

decline、decrease、depression、drop、fall、lower、reduction

　 　 　 　

「neuro」

　　[★]

• comb form.

• ニューロ、神経

関

nerve、nervi、nervous、nervus、neural、neuron