II. Physiology
-
Corticospinal tract (motor, lateral cord) transmits motor signals from the cerebral cortex
- Fibers cross the midline at the Brain Stem and course to the contralateral Muscles
- Motor fibers Synapse in the anterior horn (grey matter of the spinal cord)
- Upper Motor Neurons (UMN) are from the cerebral cortex to the Synapse
- Affect the cerebral cortex, Brainstem and Corticospinal tracts
- Lower Motor Neurons (LMN) are from the Synapse to the Muscle
- Affect the anterior horn (spinal cord), nerve roots, and Peripheral Nerves
- Upper Motor Neurons (UMN) are from the cerebral cortex to the Synapse
III. Causes: Examples
IV. Signs: Upper Motor Neuron Lesion findings
- Muscle group weakness (not complete paralysis)
- Minimal Muscle atrophy
- "Clasp-knife" spasticity
- Initial resistance to motion is strongest
- Once initial resistance gives-way, resistance to motion is less for remaining range of motion
- Hyperreflexia with or without Clonus
- Babinski Reflex positive response
- Pathologic spread of reflexes
- Muscle Contractions produce motions in Muscles other than the one tested
- Precaution
- Cauda equina are all Peripheral Nerves
- Upper Motor Neuron findings for levels below T12 or L1 must be central lesions in the higher cord
- Strongly consider severe Cervical Spinal Stenosis
- Reference
- Robbins (2012) Board Review Express, San Jose
Images: Related links to external sites (from Bing)
Related Studies
| Concepts | Pathologic Function (T046) |
| SnomedCT | 264247003, 299738004 |
| English | UPPER MOTOR NEURONE LESION, UMNL - Upper motor neur lesion, upper motor neurone lesion, upper motor neuron lesion, lesions motor neuron upper, lesions motor neurone upper, Upper motor neurone lesion NOS, Upper motor neurone lesion (disorder), Upper motor neurone lesion, UMNL - Upper motor neurone lesion, Upper motor neurone lesion (finding) |
| Italian | Lesione del motoneurone superiore, Lesione del motoneurone superiore NAS |
| Dutch | bovenste motorische neuronlaesie NAO, bovenste motorische neuronlaesie |
| French | Lésion des motoneurones supérieurs SAI, LESION DU NEURONE MOTEUR SUP, Lésion du motoneurone supérieur |
| German | obere Motorneuronlaesion NNB, NEURONENSCHAEDIGUNG MOTORISCHE OB, obere Motorneuronlaesion |
| Portuguese | Lesão traumática do neurónio motor superior NE, LESAO DO NEURONIO MOTOR SUPERIOR, Lesão do neurónio motor superior |
| Spanish | Lesión de las neuronas motoras superiores NEOM, NEURONA MOTORA SUPERIOR, LESION, lesión de la motoneurona superior, lesión de la motoneurona superior (hallazgo), lesión de la neurona motora superior, lesión de la neurona motora superior (hallazgo), Lesión de la primera motoneurona |
| Japanese | 上位運動ニューロンの病変ＮＯＳ, 上位運動ニューロンの病変, ｼﾞｮｳｲｳﾝﾄﾞｳﾆｭｰﾛﾝﾉﾋﾞｮｳﾍﾝ, ｼﾞｮｳｲｳﾝﾄﾞｳﾆｭｰﾛﾝﾉﾋﾞｮｳﾍﾝNOS |
| Czech | Léze horního motorického neuronu, Léze horního motorického neuronu NOS |
| Hungarian | Felső motoneuron laesio k.m.n., Felső motoneuron laesio |
Ontology: Upper motor neuron (C0524458)
| Concepts | Cell (T025) |
| SnomedCT | 91769000 |
| English | motor neuron upper, motor neurons upper, upper motor neuron, Upper motor neuron, Upper motor neuron (cell) |
| Spanish | neurona motora superior (célula), neurona motora superior |
