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31 Cards in this Set
- Front
- Back
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Lateral pathways |
a. Newer
b. Crossed c. distal muscles for fine, skilled movements d. corticospinal tract, rubrospinal tract |
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Medial pathways
a. phylogenetically newer/older? b. crossing? c. Control of...? d. Examples? (3) |
a. older
b. Uncrossed or bilateral projecting c. axial and proximal muscles that control posture and balance d. Vestibulospinal, descending medial longitudinal fasciculus, reticulospinal tracts |
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What are 2 tracts that are located medially but physiologically more 'lateral'?
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Tectospinal tract
Ventral corticospinal tract |
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Where are lower motor neurons arranged?
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Ventral horns of spinal cord
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What do Medial motor neurons control?
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Proximal muscles, especially extensors
Postural tone, upright stance |
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What do lateral motor neurons control?
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Distal muscles, typically flexors
Fine motor control |
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What does corticofugal mean?
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Axons that convey signals away from cortex
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What are corticobulbar fibers?
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Axons conveying signals from cortex to brainstem
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What are corticospinal fibers?
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Axons conveying signals from cortex to spinal cord
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What is an example of a corticofugal pathway that does not originate from neurons in the primary motor cortex?
What do they signal? |
Neurons in the somatic sensory regions of anterior parietal lobe --> synapse on local circuit neurons near trigeminal nuclei/dorsal horn of spinal cord
Modulate proprioceptive signals |
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Lateral corticospinal tract
Location of neuron cell bodies? (3) |
Precentral gyrus (area 4)
Postcentral gyrus (areas 3,1,2) Premotor area (area 6) |
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Lateral corticospinal tract
Course? |
Internal capsule --> cerebral peduncles --> pyramids --> decussate at junction of spinal cord and medulla --> descend the length of the spinal cord in lateral funiculus
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Lateral corticospinal tract
Termination? |
Gray matter throughout length of spinal cord (mostly in dorsolateral aspect of ventral horn)
Contralateral to cells of origin |
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Ventral corticospinal tract
Location of neuron cell bodies? |
Precentral gyrus (area 4) and premotor area (area 6)
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Ventral corticospinal tract
Course? |
Runs w/ lateral corticospinal tract through internal capsule, cerebral peduncles, and pyramids --> most decussate in caudal medulla --> ventral funiculus
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Ventral corticospinal tract
Termination? |
In thoracic region, synapse in gray matter
Either ipsilateral or bilateral to cells of origin |
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Rubrospinal tract
Location of neuron cell bodies? |
Red nucleus in midbrain
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Rubrospinal tract
Course? |
Decussate immediately --> midbrain, pons, medulla --> lateral funiculus in spinal cord --> cervical cord
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Rubrospinal tract
Termination? |
Gray matter of cervical spinal cord (dorsolateral aspect of ventral horn)
Contralateral |
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Tectospinal tract (colliculospinal tract)
Location of neuron cell bodies? |
Superior colliculus in midbrain
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Tectospinal tract (colliculospinal tract)
Course? |
Fibers cross midline in midbrain --> spinal cord --> medial portion of ventral funiculus w/ MLF --> low cervical levels
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Tectospinal tract (colliculospinal tract)
Terminaton? |
Gray matter of low cervical vertebra
Contralateral |
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Vestibulospinal tract
Location of neuron cell bodies? |
Lateral vestibular nucleus in pons
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Vestibulospinal tract
Course? |
Ipsilaterally through brainstem --> spinal cord, ventral funiculus
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Vestibulospinal tract
Termination? |
Ventromedial aspect of ventral horn, all spinal levels
Ipsilateral |
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Descending medial longitudinal fasciculus (2)
Location of neuron cell bodies? |
Pontine reticular formation
Bilateral medial vestibular nuclei of medulla |
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Descending medial longitudinal fasciculus
Course? |
Ipsilateral in brainstem w/tectospinal tract --> spinal cord, ventral funiculus
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Descending medial longitudinal fasciculus
Termination? |
Cervical spinal cord --> synapse in gray matter
Ipsilateral or bilateral |
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Medial and lateral reticulospinal tracts
Location of neuron cell bodies? |
Lateral = reticular formation cells in medulla
Medial = pons |
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Medial and lateral reticulospinal tracts
Course? |
Brainstem --> spinal cord --> medial and lateral bundle --> fibers terminate bilateral, with ipsilateral predominance in the ventromedial aspect of the ventral horn
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Medial and lateral reticulospinal tracts
Termination? |
All spinal levels, bilateral termination (ipsilateral predominance) on ventromedial aspect of ventral horn
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