Term
| lesion to basal ganglia causes: |
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Definition
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Term
| lesion to cerebellum causes: |
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Definition
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Term
| cerebralcortical lesions cause: |
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Definition
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Term
| with the pyramidal system, upper motor neurons have both their cell bodies and axons in the ___. The cell bodies are in the ___ ___. The axons descend to the ___ level or to the __ ___ and synapse on ___ ___ ___ in either ___ __ ___ ___ in the brainstem, or on ___ ___ ___ at the cord level. |
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Definition
- CNS
- cerebral cortex
- brainstem
- spinal cord
- lower motor neurons
- cranial nerve motor nucleus
- spinal motor neurons |
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Term
| Upper motor neurons synapse where and with what? |
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Definition
- brainstem level with cranial nerve motor nuclei (lower motor neuron)
- spinal cord level with spinal motor neurons (lower motor neuron) |
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Term
| Lower motor neurons have their cell bodies in the ___, but their axons in the ___. |
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Definition
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Term
| The cell bodies of lower motor neurons are specifically located where? |
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Definition
- brainstem in the cranial nerve motor nuclei
- ventral motor horn of spinal cord |
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Term
| The axons of lower motor neurons form what? |
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Definition
| - motor component of cranial/spinal nerves |
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Term
| where do lower motor neurons synapse? |
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Definition
- on the skeletal muscle
- also called "final common path" neurons |
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Term
| Upper motor neuron lesion manifestations: |
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Definition
- if lesion before decussation of pyramids (where axons cross over), then the manifestations are exhibited on the contralateral side of the lesion
- if lesion is after decussation of pyramids, then the manifestations are on the ipsilateral side as the lesion |
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Term
| Where are possible sites of damage on a lower motor neuron? |
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Definition
- cranial nerve motor nuclei and/or their axons
- ventral horn spinal motor neurons and/or their axons |
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Term
| Lower motor neurons manifestations are always ___. |
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Definition
| IPSILATERAL to the lesion |
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Term
| Upper motor neuron lesion manifestations: |
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Definition
- spastic paralysis
- hyperactive deep tendon reflexes
- Babinski sign present |
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Term
| Lower motor neuron manifestations: |
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Definition
- flaccid paralysis
- atrophy
- hypoactive or absent deep tendon reflexes
- fasciculations
- |
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Term
| if you seen Babinksi sign, what kind of lesion? |
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Definition
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Term
| If you see pronounce atrophy, what kind of lesion are you looking at? |
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Definition
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Term
| If you note hyperactive reflexes, what kind of lesion is it? |
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Definition
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Term
| If you note hypoactive or absent reflexes what kind of lesion are you seeing? |
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Definition
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Term
| If you note flaccid paralysis what kind of lesion is it? |
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Definition
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Term
| If you note spastic paralysis, what kind of lesion is it? |
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Definition
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Term
| If you note fasciculations (small localized muscle twitches), what kind of lesion is it? |
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Definition
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Term
| what two tracts make up the pyramidal system? |
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Definition
- Corticobulbar tract
- Corticospinal tract: lateral and ventral corticospinal tracts |
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Term
| what does the pyramidal system originate from? |
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Definition
| - cerebral cortex pyramidal cells of Betz in layers 3 and 5 of cerebral cortex |
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Term
| describe the pyarmidal cells of betz: |
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Definition
- large multipolar neurons with pyramid shaped cell bodies
- located in layers 3 and 5 of cerebral cortex and in other coritical and subcortical regions
- about 1 million of these axons descend from the 6th layer of the cerebral cortex to form the corticobulbar and corticospinal tracts of the pyramidal system |
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Term
| The axons of what cells form the corticospinal and corticobulbar tracts? |
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Definition
| - pyramidal cells of Betz |
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Term
describe the internal capsule:
TEST QUESTION ON THIS |
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Definition
| - organized compact bundle of ascending and descending myelinated fibers passing between the thalamus and the basal ganglia |
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Term
| what two structures do the myelinated fibers of the internal capsule pass between? |
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Definition
| - thalamus and basal ganglia |
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Term
| the anterior limb of the internal capsule has what? |
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Definition
- anterior thalamic radiations
- frontopontine fibers |
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Term
| the genu of the internal capsule has what? |
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Definition
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Term
| the posterior limb of the internal capsule has what? |
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Definition
| - major motor and sensory pathways |
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Term
| where does the optic tract terminate? |
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Definition
| - lateral cuneate nucleus of thalamus, then you have optic radiations back to occipital area of brain |
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Term
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Definition
- diverging fibers of internal capsule that radiate in all directions to the cerebral cortex
- converging fibers of internal capsule that come from all directions of the cerebral cortex and go to lower brain structures and the spinal cord |
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Term
| what three sets of fibers pass through the cerebral peduncles from medial to lateral? |
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Definition
- corticopontine fibers from frontal lobe
- corticobulbar and coritcospinal fibers
- corticopontine fibers from parietal temporal, and occipital lobes |
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Term
| if someone injures their cerebral peduncles, what will you see? |
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Definition
| - paralysis on contralateral side of lesion |
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Term
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Definition
- CN V motor nucleus
- corticopontine fibers from fronal lobe
- corticobulbar and corticospinal fibers
- corticopontine fiber from parietal, occipital, and temporal lobes |
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Term
| the lateral corticospinal tract is in ___ ___ of the spinal cord. the ventral corticospinal tract is the ___ ___ and ___ levels of the spinal cord. |
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Definition
- all levels
- cervical
- upper thoracic |
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Term
| The corticobulbar tract starts in the primary motor cortex then goes to the corona radiata and then the genu of the internal capsule. What three places does it go to from there? |
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Definition
- trigeminal motor nucleus on both sides> muscles of mastication
- facial motor nucleus on both sides> muscles of facial expression
- middle 1/3 of cerebral peduncle |
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Term
| from the middle 1/3 of the cerebral peduncle, where does the corticobulbar tract go? |
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Definition
- pons
- medulla
From the medulla the corticobulbar tract goes two places:
- hypoglossal nucleus on both sides> tongue muscles
- nucleus ambiguus (motor nuclues of IX, X, XI cranial nerves on both sides)> muscles of pharynx, larynx, sternocledomastoid, and trapezius |
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Term
| so ultimately what muscles does the corticobulbar tract control? |
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Definition
- muscles of facial expression (CN VII)
- muscles of mastication (CN V3)
- tongue muscles except for palatoglossus (CN XII)
- pharynx muscles (CN IX and X)
- larynx muscles (CN IX and X)
- sternocleidomastoid (CN XI)
- trapezius (CN XI) |
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Term
| so what cranial nerves is the corticobulbar tract associated with? |
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Definition
- CN VII (facial expression)
- CN V3 (mastication)
- CN IX and X (larynx and pharynx)
- CN XI (sternocleidomastoid and trapezius)
- CN XII (tongue muscles) |
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Term
| the motor nucleus for the trigeminal nerve is in the ___. |
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Definition
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Term
| the hypoglossal nucleus and nuclues ambiguus is in the |
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Definition
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Term
| what motor nuclei do NOT receive direct innervation from the primary motor cortex? |
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Definition
- oculomotor nucleus
- trochlear nucleus
- abducens nucleus |
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Term
| the nuclei that do not receive direct innervation by the primary motor cortex, are instead innervated by what? |
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Definition
- oculomotor, trochlear, and abducens nuclei
- bilaterally innervated from gaze centers in the midbrain and pons, which in turn receive innervation from gaze centers in the frontal lobe |
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Term
| gaze centers in the frontal lobe innervate gaze centers in the __ and ___. These gaze centers then innervate the __, __ and ___ nuclei. |
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Definition
- pons
- medulla
- oculomotor, trochlear, and abducens |
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Term
| The motor nucleus of cranial nerve VII that innervates the lower half of the face, receives projections from ____ cerebral hemisphere only. |
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Definition
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Term
| Since the lower facial muscles of facial expression are only innervated by the contralateral cerebral hemisphere, and upper motor neuron lesion would only knock out the ___ facial muscles on the ___ side of the lesion b/c the upper face would be innervated by neurons from the ipsilateral hemisphere. But a lower motor neuron lesion that occurs after the the facial motor nucleus would not out ___ and ___ facial muscles on the ___ side. |
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Definition
- lower
- contralateral
- upper and lower
- ipsilateral side |
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Term
| an upper motor neuron lesion to the facial nerve would cause: |
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Definition
| - paralysis on contralateral side, lower face muscles only |
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Term
| a lower motor neuron lesion to the facial nerve would cause: |
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Definition
| - complete facial paralysis on the ipsilateral side |
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Term
| an example of a lower motor neuron lesion in the facial nerve is called: |
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Definition
| Bell's palsy, complete paralysis on ipsilateral side of face |
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Term
| the corticobulbar tract goes through the __ of the internal capsule, while the corticospinal tract goes through the ___ __ of the internal capsule. |
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Definition
- corticobulbar> genu
- corticospinal> posterior limb |
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Term
| After going through the posterior limb of the internal capsule, the corticospinal tract goes where? |
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Definition
| - middle 1/3 of crus cerebri of midbrain |
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Term
| 10-15% of corticospinal tract fibers do not cross at the pyramids in medulla. What tract do these become and what path do they take? |
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Definition
- ventral corticospinal tract fibers
- become the lateral faniculus of spinal cord in the upper thoracic and cervical regions
- cross midline at the anterior white commissure> motor neurons in the ventral horn> muscles of the neck and upper limbs |
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Term
| muscles of the neck and upper limb are mostly innervated by: |
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Definition
| - motor neurons in the ventral corticospinal tract in the lateral fasciculus in the upper thoracic and cervical regions |
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Term
| Most corticospinal tract fibers DO cross over. These become what tract and what is their path? |
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Definition
- lateral corticospinal tract in the lateral funiculus of all spinal cord regions
- motor neurons in ventral horn> muscle of neck, trunk and limbs |
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Term
| so the ventral corticospinal trunk only innervates ___ and ___ muscles, while the lateral corticospinal tract innervates ___, ___, and ___ muscles. |
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Definition
- neck and arm
- neck, trunk, and limb |
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Term
| the reason you don't see the corticobulbar tract in a cross section of spinal cord is b/c the CNV nucleus is in the internal ___, CNVII is at junction of pons and medulla, and the hypoglossal nucleus and nucleus ambiguus are in the ___ ___. |
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Definition
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