II. Physiology

  1. Corticospinal tract (motor, lateral cord) transmits motor signals from the cerebral cortex
    1. Fibers cross the midline at the Brain Stem and course to the contralateral Muscles
  2. Motor fibers Synapse in the anterior horn (grey matter of the spinal cord)
    1. Upper Motor Neurons (UMN) are from the cerebral cortex to the Synapse
      1. Affect the cerebral cortex, Brainstem and Corticospinal tracts
    2. Lower Motor Neurons (LMN) are from the Synapse to the Muscle
      1. Affect the anterior horn (spinal cord), nerve roots, and Peripheral Nerves

IV. Signs: Lower Motor Neuron Lesion findings

  1. Flaccid Paralysis
  2. Muscular atrophy
  3. Muscle Fasciculation (Muscle Twitch)
    1. Involuntary fine Muscle Contractions and relaxations of an entire motor unit synchronously
    2. May be a benign finding, in the absence of a lower motor lesion
  4. Muscle fibrillations
    1. Small, local Muscle Contractions of single Muscle fibers that contract independently of surrounding fibers
    2. Contractions are typically rapid, irregular and unsynchronized
  5. Hyporeflexia
  6. Absent Babinski Reflex

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Related Studies

Ontology: Muscle twitch (C0231530)

Definition (NCI_FDA) The occurrence of a single contraction or a series of contractions of a muscle.
Definition (NCI) The occurrence of a single contraction or a series of contractions of a muscle.
Concepts Sign or Symptom (T184)
ICD10 R25.3
SnomedCT 60238002, 249966004
English Muscle twitch, Muscle twitching, Twitches, muscle twitches (symptom), muscle twitches, Twitching NOS, jerks, twitches, jerking, muscle twitch, twitch, twitched, muscle twitching, jerk, jerked, TWITCHING, Twitch, Twitching, Muscle twitch (finding), twitching, Twitch(ing)
Italian Contrazione muscolare, Contratture, Contrazione, Contrattura di muscolo
Dutch trekking, trekkingen, spiertrekking, spiertrekkingen
French Contractions musculaires, Soubresauts musculaires, Contractions, CONTRACTION CLONIQUE, Contractions fasciculaires
German Zucken, ZUCKUNGEN, Muskelzucken
Portuguese Fasciculações musculares, Contração muscular, CONTRACCAO CLONICA, Fasciculação e fibrilhação muscular
Spanish Sacudida, Sacudidas, Tirón muscular, SACUDIDA MUSCULAR, tirón muscular (hallazgo), tirón muscular, Sacudidas musculares
Japanese 筋攣縮, ピクピクした動き, 攣縮, キンレンシュク, レンシュク, ピクピクシタウゴキ
Czech Svalové fascikulace, Fascikulace, Svalová fascikulace
Hungarian Izomrángás, Izomrángatódzás, Rángatózások

Ontology: Lower motor neurone lesion (C0442865)

Concepts Pathologic Function (T046)
SnomedCT 264077003, 299737009
Italian Lesione del motoneurone inferiore, Lesione del motoneurone inferiore NAS
Dutch lagere motorische neuronlaesie NAO, lagere motorische neuronlaesie
French Lésion des motoneurones inférieurs SAI, LESION DU MOTONEURONE INFERIEUR, Lésion du motoneurone inférieur
German untere Motorneuronlaesion NNB, NEURONENSCHAEDIGUNG MOTORISCHE UN, untere Motorneuronlaesion
Portuguese Lesão traumática do neurónio motor inferior NE, LESAO DO NEURONIO MOTOR PERIFERIC, Lesão do neurónio motor inferior
Spanish Lesión de neurona motor inferior NEOM, lesión de la neurona motora inferior (hallazgo), lesión de la neurona motora inferior, Lesión de la segunda motoneurona
Japanese 下位運動ニューロンの病変NOS, 下位運動ニューロンの病変, カイウンドウニューロンノビョウヘン, カイウンドウニューロンノビョウヘンNOS
English LOWER MOTOR NEURONE LESION, Lower motor neurone lesion NOS, Lower motor neurone lesion (disorder), Lower motor neurone lesion, Lower motor neurone lesion (finding)
Czech Léze dolního motorického neuronu, Léze dolního motorického neuronu NOS
Hungarian Alsó motoneuron laesio, Alsó motoneuron laesio k.m.n.

Ontology: Lower motor neuron (C0524459)

Concepts Cell (T025)
SnomedCT 91770004
English lower motor neurons, lower motor neuron, neuron lower motor, Lower motor neuron, Lower motor neuron (cell)
Spanish neurona motora inferior (célula), neurona motora inferior

Ontology: Fasciculation, Skeletal Muscle (C0541957)

Concepts Finding (T033)
MSH D005207
Dutch fasciculatie skeletspier
German Faszikulation des Skelettmuskels
Italian Fascicolazione di muscolo scheletrico, Fascicolazione muscolo-scheletrica
Portuguese Fasciculação de músculo esquelético
Spanish Fasciculación de la musculatura esquelética
Japanese 骨格筋線維束性収縮, コッカクキンセンイソクセイシュウシュク
French Fasciculation d'un muscle squelettique
English Fasciculation, Skeletal Muscle, Fasciculation skeletal muscle, Fasciculations, Skeletal Muscle, Muscle Fasciculation, Skeletal, Muscle Fasciculations, Skeletal, Skeletal Muscle Fasciculation, Skeletal Muscle Fasciculations
Czech Záškuby kosterního svalu
Hungarian Vázizom fasciculatio
Norwegian Skjelettmuskelfascikulasjon, Fascikulasjon, skjelettmuskel

Ontology: Fibrillation skeletal muscle (C0541960)

Concepts Finding (T033)
Dutch fibrillatie skeletspier
French Fibrillation d'un muscle squelettique
German Fibrillation des Skelettmuskels
Italian Fibrillazione di muscolo scheletrico
Portuguese Fibrilhação de músculo esquelético
Spanish Fibrilación de la musculatura esquelética
Japanese 骨格筋線維性収縮, コッカクキンセンイセイシュウシュク
Czech Fibrilace kosterního svalu
English Fibrillation skeletal muscle
Hungarian Vázizom fibrillatio