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26 Cards in this Set
- Front
- Back
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What are the 3 gray matter divisions of the spinal cord?
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1. Dorsal horn
2. Intermediate zone 3. Ventral horn |
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What level is the phrenic nucleus located?
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C3-C5
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What level is Clarke's nucleus (nuclei dorsalis) located?
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T1-L3
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What level is the lateral horn or intermediolateral cell column located?
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T1-L3
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What are the three areas of spinal cord white matter?
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Dorsal, lateral, and ventral funiculi
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What are the major ascending tracts?
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1. Dorsal columns
2. Spinothalamic tract 3. Spinocerebellar tract |
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What is the major descending tract?
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Corticospinal tract
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What are the two divisions of the dorsal funiculus once above T6?
Note: which part of the body does each deal with? |
1. (laterally) fasciculus cuneatus - deals with arms and upper body
2. (medially) fasciculus gracilis - deals with legs and lower body |
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What is the path to activation of the stretch reflex (i.e. patellar or monosynaptic)
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1. Tap patellar tendon
2. Stretch the quadricep femoris muscle 3. Activate stretch receptor 4. Activate sensory DRG neurons 5. Activate lower motor neurons 6. Muscle contracts |
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What is the flexor withdrawal reflex?
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Withdrawal of a limb from a painful stimulus, a protective reflex, multisynaptic
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What is the function of the posterior column-medial lemniscal pathway?
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Mediates conscious proprioception, vibration, light touch, and fine tactile discrimination
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Where does the posterior column-medial lemniscal pathway decussate?
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In the brainstem
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What is the pathway of the posterior column-medial lemniscal pathway?
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1. Peripheral receptor
2. DRG sensory neuron 3. Ascends fasciculus gracilis or cuneatus 4. Synapses in nucleus gracilus or cuneatus 5. Decussages via internal arcuate fibers in brainstem 6. Forms medial lemniscus 7. Synapses in thalamus 8. Ascends through internal capsule 9. Synapses in postcentral gyrus |
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What is the function of the spinothalamic tract?
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Mediates pain, temperature, and crude touch sensation.
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Where does the spinothalamic tract decussate?
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Near the point of entry in the spinal cord
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What is the pathway of the spinothalamic tract?
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1. Peripheral receptor
2. DRG sensory neuron 3. Synapses in substantia gelatinosa 4. Decussates in ventral white commisure 5. Ascends spinothalamic tract 6. Synapses in thalamus 7. Ascends in internal capsule 8. Synapses in postcentral gyrus |
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What is the function of the spinocerebellar tract?
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Mediates unconscious proprioception
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Is the posterior spinocerebellar tract ipsilateral or contralateral?
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Ipsilateral
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What is the path of the posterior spinocerebellar tract?
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From ipsilateral leg,
2. Synapses Clarke's nucleus (only seen above L2) |
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What is the path of the anterior spinocerebellar tract?
Note: ipsilateral or contralateral? |
Via nucleus proprius...
2. crosses in cord and again in cerebellum Note: effects are mainly ipsilateral |
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What is the function of the corticospinal tract?
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Mediates descending motor control
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Where does the corticospinal tract decussate?
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85% in brainstem - decussates at pyramidal decussation and descends the lateral corticospinal tract
15% in spinal cord - descends as the medical corticospinal tract and then decussates at the ventral white commissure |
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What is the pathway of the corticospinal tract?
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1. Motor cortex
2. through internal capsule 3. cerebral peduncle 4. pons 5. crosses at the pyramidal decussation in brainstem 6. 85% decussate in brainstem pyramidal decussation and descend as the lateral corticospinal tract 7. 15% stay ipsilateral in the brainstem, descend as the medial corticospinal tract and then decussate in the ventral white commissure |
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What are the targets of the corticospinal tract?
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Interneurons and lower motor neurons in the ventral horn
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What would a lesion in the corticospinal tract produce?
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- upper motor neuron signs including:
* spastic paralysis * hyperactive reflexes such as Babinski sign |
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How do lower motor neuron lesion signs differentiate from upper motor neuron lesion signs?
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Lower motor neuron signs include:
- Flacid paralysis - Atrophy - decreased strength/muscle tone - decreased deep tendon reflexes Upper motor neuron signs include: - Spastic paralysis - Hyeractive reflexes such as Babinski sign - mild atrophy - increased muscle tone |
