Podcast
Questions and Answers
What is the anatomical location of the cell body of lower motor neurons in the descending pathway?
What is the anatomical location of the cell body of lower motor neurons in the descending pathway?
Which descending tract is responsible for the primary control of voluntary movement?
Which descending tract is responsible for the primary control of voluntary movement?
What is the main function of neurons in the descending pathway?
What is the main function of neurons in the descending pathway?
What is the primary role of lower motor neurons in the descending pathway?
What is the primary role of lower motor neurons in the descending pathway?
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What is the main pathway for voluntary, discrete, skilled movement?
What is the main pathway for voluntary, discrete, skilled movement?
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Involvement of which area results in a cortical lesion related to motor pathways?
Involvement of which area results in a cortical lesion related to motor pathways?
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Which lesion type involves damage to the upper motor neuron?
Which lesion type involves damage to the upper motor neuron?
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Which neuron type is referred to as the 'final common pathway' in the descending pathway?
Which neuron type is referred to as the 'final common pathway' in the descending pathway?
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Where are the origin of the tract fibers for the corticospinal tract located?
Where are the origin of the tract fibers for the corticospinal tract located?
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Which pathway utilizes 3 neurons in controlling skeletal muscle activity?
Which pathway utilizes 3 neurons in controlling skeletal muscle activity?
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What is the primary function of the pyramidal and extrapyramidal tracts discussed?
What is the primary function of the pyramidal and extrapyramidal tracts discussed?
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Which descending tract is NOT part of the primary control of voluntary movement?
Which descending tract is NOT part of the primary control of voluntary movement?
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Where do fibers of the pyramidal tract arise from the Primary Motor Cortex?
Where do fibers of the pyramidal tract arise from the Primary Motor Cortex?
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Which area does NOT provide axons directly controlling movement to the pyramidal tract?
Which area does NOT provide axons directly controlling movement to the pyramidal tract?
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Where are the neurons that specifically influence eye movements located?
Where are the neurons that specifically influence eye movements located?
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Which area constitutes the sensorimotor cortex giving rise to the pyramidal tract?
Which area constitutes the sensorimotor cortex giving rise to the pyramidal tract?
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Where are fibers of the pyramidal tract arising from the Primary Sensory Cortex?
Where are fibers of the pyramidal tract arising from the Primary Sensory Cortex?
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What is the primary function of the pyramidal tract?
What is the primary function of the pyramidal tract?
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Which reticulospinal tract is almost entirely ipsilateral and facilitates extensor motor neurons?
Which reticulospinal tract is almost entirely ipsilateral and facilitates extensor motor neurons?
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Which reticulospinal tract has both crossed and uncrossed fibers and is inhibitory to extensor motor neurons?
Which reticulospinal tract has both crossed and uncrossed fibers and is inhibitory to extensor motor neurons?
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Which function is attributed to the Medullary Reticulospinal Tract but not to the Pontine Reticulospinal Tract?
Which function is attributed to the Medullary Reticulospinal Tract but not to the Pontine Reticulospinal Tract?
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Which part of the spinal cord primarily carries the Pontine Reticulospinal Tract?
Which part of the spinal cord primarily carries the Pontine Reticulospinal Tract?
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What is the primary feature that distinguishes the Medullary Reticulospinal Tract from the Pontine Reticulospinal Tract?
What is the primary feature that distinguishes the Medullary Reticulospinal Tract from the Pontine Reticulospinal Tract?
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Which nervous system functions can be influenced by the Medullary Reticulospinal Tract?
Which nervous system functions can be influenced by the Medullary Reticulospinal Tract?
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What type of motor deficit would a lesion above the pyramidal decussation produce?
What type of motor deficit would a lesion above the pyramidal decussation produce?
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Which system is responsible for the cross-over of fibers in the medulla?
Which system is responsible for the cross-over of fibers in the medulla?
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In the context provided, what would be the result of a lesion below the pyramidal decussation?
In the context provided, what would be the result of a lesion below the pyramidal decussation?
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What is the motor strength observed over the right upper extremity in the provided neurological examination?
What is the motor strength observed over the right upper extremity in the provided neurological examination?
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Where does the decussation occur for fibers related to pain and thermal sensation in the spinal cord?
Where does the decussation occur for fibers related to pain and thermal sensation in the spinal cord?
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Based on the presented case evaluation, what can be concluded about the location of the lesion?
Based on the presented case evaluation, what can be concluded about the location of the lesion?
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What is the main function of the Corticospinal tract?
What is the main function of the Corticospinal tract?
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Which part of the brainstem is NOT associated with the origin of the Extrapyramidal tracts?
Which part of the brainstem is NOT associated with the origin of the Extrapyramidal tracts?
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What is a characteristic feature of Lower Motor Neuron lesions?
What is a characteristic feature of Lower Motor Neuron lesions?
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Where does the decussation occur for fibers related to voluntary motor control in the Corticospinal tract?
Where does the decussation occur for fibers related to voluntary motor control in the Corticospinal tract?
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Which type of lesion involves damage to Upper Motor Neurons?
Which type of lesion involves damage to Upper Motor Neurons?
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Which anatomical location is associated with Reflex Arc in the motor pathways?
Which anatomical location is associated with Reflex Arc in the motor pathways?
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What would be the result of a lesion affecting the fibers above the pyramidal decussation?
What would be the result of a lesion affecting the fibers above the pyramidal decussation?
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Which area of the spinal cord would show paralysis following a lesion involving the lateral corticospinal tract?
Which area of the spinal cord would show paralysis following a lesion involving the lateral corticospinal tract?
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What motor function is directly impacted by lesions involving the uncrossed fibers of the anterior corticospinal tract?
What motor function is directly impacted by lesions involving the uncrossed fibers of the anterior corticospinal tract?
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In cases of spinal cord lesions, why does paralysis occur on the ipsilateral side of the body?
In cases of spinal cord lesions, why does paralysis occur on the ipsilateral side of the body?
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How is motor control affected if there is a lesion below the pyramidal decussation?
How is motor control affected if there is a lesion below the pyramidal decussation?
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What distinguishes the fibers of the Lateral Corticospinal Tract from those of the Anterior Corticospinal Tract?
What distinguishes the fibers of the Lateral Corticospinal Tract from those of the Anterior Corticospinal Tract?
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What is the significance of the feedback information from muscles, joints, skin, and tendons in the movement process?
What is the significance of the feedback information from muscles, joints, skin, and tendons in the movement process?
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Which system plays a supporting role in the production of well-coordinated movements?
Which system plays a supporting role in the production of well-coordinated movements?
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What is the primary function of the cerebellum in relation to movement?
What is the primary function of the cerebellum in relation to movement?
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What type of symptoms would a patient experience if there is an occlusion of vessels supplying the area where CST fibers pass through?
What type of symptoms would a patient experience if there is an occlusion of vessels supplying the area where CST fibers pass through?
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Which part of the internal capsule contains fibers controlling the upper limbs?
Which part of the internal capsule contains fibers controlling the upper limbs?
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What is the difference between the anterior (ventral) and lateral CST regarding crossing of fibers?
What is the difference between the anterior (ventral) and lateral CST regarding crossing of fibers?
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Where do CST fibers controlling lower extremities terminate within the spinal cord?
Where do CST fibers controlling lower extremities terminate within the spinal cord?
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What is the significance of pyramidal decussations in the corticospinal tract?
What is the significance of pyramidal decussations in the corticospinal tract?
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Which part of the CST has a somatotopic arrangement with fibers controlling lower extremities located posteriorly?
Which part of the CST has a somatotopic arrangement with fibers controlling lower extremities located posteriorly?
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In a patient where the tongue is both atrophied and deviated to the right, what type of lesion is most likely present?
In a patient where the tongue is both atrophied and deviated to the right, what type of lesion is most likely present?
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If a stroke patient presents with a deviated tongue to the right but without atrophy, what type of lesion is most likely responsible?
If a stroke patient presents with a deviated tongue to the right but without atrophy, what type of lesion is most likely responsible?
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If a resident notices a stroke patient's tongue is deviated to the right but not atrophied, what type of lesion is most likely involved?
If a resident notices a stroke patient's tongue is deviated to the right but not atrophied, what type of lesion is most likely involved?
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When a patient wakes up unable to move the entire left half of the face, what type of lesion is typically indicated?
When a patient wakes up unable to move the entire left half of the face, what type of lesion is typically indicated?
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In a scenario where a stroke patient can still wrinkle both eyebrows but cannot move the left lower half of the face, where is the lesion likely located?
In a scenario where a stroke patient can still wrinkle both eyebrows but cannot move the left lower half of the face, where is the lesion likely located?
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What type of lesion would be suspected in a stroke patient presenting with atrophy and deviation of the tongue to the right?
What type of lesion would be suspected in a stroke patient presenting with atrophy and deviation of the tongue to the right?
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What is the primary role of the extrapyramidal system in movement coordination?
What is the primary role of the extrapyramidal system in movement coordination?
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Which brain structure relays information to both the brainstem centers and lower motor neurons for movement coordination?
Which brain structure relays information to both the brainstem centers and lower motor neurons for movement coordination?
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What type of movement feedback is essential for the fine-tuning and adjustment of movement coordination?
What type of movement feedback is essential for the fine-tuning and adjustment of movement coordination?
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Where does the cerebellum primarily receive sensory inputs for movement coordination?
Where does the cerebellum primarily receive sensory inputs for movement coordination?
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Which descending tract plays a significant role in voluntary, discrete, skilled movement coordination?
Which descending tract plays a significant role in voluntary, discrete, skilled movement coordination?
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In the coordination of movement, what does the cerebellum relay information to enhance fine-tuning?
In the coordination of movement, what does the cerebellum relay information to enhance fine-tuning?
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What specific movements are controlled by the Supplementary Motor Area according to the text?
What specific movements are controlled by the Supplementary Motor Area according to the text?
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Which artery supplies the dorsal and lateral portions of the cerebral hemispheres according to the provided text?
Which artery supplies the dorsal and lateral portions of the cerebral hemispheres according to the provided text?
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In case of an occlusion of the Anterior Cerebral Artery (ACA), what symptom is likely to be observed according to the text?
In case of an occlusion of the Anterior Cerebral Artery (ACA), what symptom is likely to be observed according to the text?
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What specific area of the brain represents lower limbs in the motor homunculus according to the text?
What specific area of the brain represents lower limbs in the motor homunculus according to the text?
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What feature distinguishes the involvement of the Middle Cerebral Artery (MCA) from that of the Anterior Cerebral Artery (ACA) when occluded according to the text?
What feature distinguishes the involvement of the Middle Cerebral Artery (MCA) from that of the Anterior Cerebral Artery (ACA) when occluded according to the text?
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What is the primary role of the BA 4 area surrounding the central sulcus as mentioned in the text?
What is the primary role of the BA 4 area surrounding the central sulcus as mentioned in the text?
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Where are the perineal muscles, legs, and feet represented on the primary motor and premotor cortex?
Where are the perineal muscles, legs, and feet represented on the primary motor and premotor cortex?
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What is unique about the location of pyramidal cells of Betz within the precentral gyrus?
What is unique about the location of pyramidal cells of Betz within the precentral gyrus?
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Which area of the primary motor and premotor cortex influences and controls the lips and face?
Which area of the primary motor and premotor cortex influences and controls the lips and face?
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What percentage of the entire corticospinal tract do the pyramidal cells of Betz give rise to?
What percentage of the entire corticospinal tract do the pyramidal cells of Betz give rise to?
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In which area of the primary motor and premotor cortex are the arms and trunk represented?
In which area of the primary motor and premotor cortex are the arms and trunk represented?
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What is distinctive about the axons from pyramidal cells of Betz in relation to spinal cord connections?
What is distinctive about the axons from pyramidal cells of Betz in relation to spinal cord connections?
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What is the significance of occlusion of a vessel supplying the area where CST fibers pass through?
What is the significance of occlusion of a vessel supplying the area where CST fibers pass through?
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Which part of the internal capsule contains fibers controlling the lower extremities according to the somatotopic arrangement?
Which part of the internal capsule contains fibers controlling the lower extremities according to the somatotopic arrangement?
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What is the primary difference between the anterior corticospinal tract and the lateral corticospinal tract?
What is the primary difference between the anterior corticospinal tract and the lateral corticospinal tract?
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What is the role of decussations in the corticospinal tract?
What is the role of decussations in the corticospinal tract?
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What would be expected if there is a lesion affecting the CST fibers above the pyramidal decussation?
What would be expected if there is a lesion affecting the CST fibers above the pyramidal decussation?
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What can be expected if there is damage to the Upper Motor Neurons in a patient?
What can be expected if there is damage to the Upper Motor Neurons in a patient?
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What is the primary characteristic that distinguishes poliomyelitis from Amyotrophic lateral sclerosis (ALS)?
What is the primary characteristic that distinguishes poliomyelitis from Amyotrophic lateral sclerosis (ALS)?
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What distinguishes severe cases of poliomyelitis from Amyotrophic lateral sclerosis (ALS)?
What distinguishes severe cases of poliomyelitis from Amyotrophic lateral sclerosis (ALS)?
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Which statement accurately describes the inheritance pattern of Amyotrophic lateral sclerosis (ALS)?
Which statement accurately describes the inheritance pattern of Amyotrophic lateral sclerosis (ALS)?
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What is a key difference between the manifestation of upper motor neuron (UMN) and lower motor neuron (LMN) lesions seen in Amyotrophic lateral sclerosis?
What is a key difference between the manifestation of upper motor neuron (UMN) and lower motor neuron (LMN) lesions seen in Amyotrophic lateral sclerosis?
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How do patients with Amyotrophic lateral sclerosis typically present due to damage to both the anterior horn cells and corticospinal tracts?
How do patients with Amyotrophic lateral sclerosis typically present due to damage to both the anterior horn cells and corticospinal tracts?
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What factor contributed to the re-emergence of polio cases in the Philippines despite being declared polio-free by WHO?
What factor contributed to the re-emergence of polio cases in the Philippines despite being declared polio-free by WHO?
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Which of the following best describes the primary function of the Corticospinal tract?
Which of the following best describes the primary function of the Corticospinal tract?
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Involvement of which area of the CNS leads to manifestations in patients associated with the motor pathways?
Involvement of which area of the CNS leads to manifestations in patients associated with the motor pathways?
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What distinguishes an Upper Motor Neuron lesion from a Lower Motor Neuron lesion?
What distinguishes an Upper Motor Neuron lesion from a Lower Motor Neuron lesion?
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Which anatomical location is associated with Reflex Arc in the motor pathways?
Which anatomical location is associated with Reflex Arc in the motor pathways?
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What is distinctive about the manifestation of extrapyramidal tracts compared to pyramidal tracts?
What is distinctive about the manifestation of extrapyramidal tracts compared to pyramidal tracts?
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Which descending tract plays a significant role in voluntary, discrete, skilled movement coordination?
Which descending tract plays a significant role in voluntary, discrete, skilled movement coordination?
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What type of lesion would result in paralysis of the contralateral lower half of the face according to the text?
What type of lesion would result in paralysis of the contralateral lower half of the face according to the text?
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Which part of the face would be unaffected by a supranuclear lesion according to the text?
Which part of the face would be unaffected by a supranuclear lesion according to the text?
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What kind of paralysis is observed in Central Facial Paralysis?
What kind of paralysis is observed in Central Facial Paralysis?
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In Bell's Palsy, what type of paralysis is typically experienced by the patient?
In Bell's Palsy, what type of paralysis is typically experienced by the patient?
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Which area innervates the lower half of the face only from contralateral sensory motor cortex?
Which area innervates the lower half of the face only from contralateral sensory motor cortex?
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What is the outcome for more than 85% of individuals with Peripheral Facial Paralysis within 1 to 2 months?
What is the outcome for more than 85% of individuals with Peripheral Facial Paralysis within 1 to 2 months?
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What is the primary role of the femoral nerve in the monosynaptic reflex arc?
What is the primary role of the femoral nerve in the monosynaptic reflex arc?
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What is the origin of the Rubrospinal Tract?
What is the origin of the Rubrospinal Tract?
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Where do the fibers of the Rubrospinal Tract terminate within the spinal cord?
Where do the fibers of the Rubrospinal Tract terminate within the spinal cord?
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Where do the motor fibers of the femoral nerve travel to in order to stimulate the quadriceps muscle?
Where do the motor fibers of the femoral nerve travel to in order to stimulate the quadriceps muscle?
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What is the function of the internal capsule in the corticospinal tract?
What is the function of the internal capsule in the corticospinal tract?
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What function is associated with the Rubrospinal Tract?
What function is associated with the Rubrospinal Tract?
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Which decussation do fibers of the Rubrospinal Tract cross immediately after originating?
Which decussation do fibers of the Rubrospinal Tract cross immediately after originating?
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Which region serves as the origin of the 1st order neuron in the corticospinal tract?
Which region serves as the origin of the 1st order neuron in the corticospinal tract?
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What is the primary influence of the Rubrospinal Tract on muscle activity?
What is the primary influence of the Rubrospinal Tract on muscle activity?
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In the monosynaptic reflex arc, what is the main effect of stimulating muscle spindles in the quadriceps muscle?
In the monosynaptic reflex arc, what is the main effect of stimulating muscle spindles in the quadriceps muscle?
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What is the significance of tapping the patellar tendon in relation to the monosynaptic reflex arc?
What is the significance of tapping the patellar tendon in relation to the monosynaptic reflex arc?
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Which tract is functionally similar to the Rubrospinal Tract and assists in its activities?
Which tract is functionally similar to the Rubrospinal Tract and assists in its activities?
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What is the primary function of the Pontine (Medial) Reticulospinal Tract?
What is the primary function of the Pontine (Medial) Reticulospinal Tract?
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Which manifestation is likely to be observed in a patient with a lesion involving the Medullary (Lateral) Reticulospinal Tract?
Which manifestation is likely to be observed in a patient with a lesion involving the Medullary (Lateral) Reticulospinal Tract?
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What is a characteristic feature of the Rubrospinal Tracts?
What is a characteristic feature of the Rubrospinal Tracts?
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In the context provided, what would be expected if there is damage to the Medullary (Lateral) Reticulospinal Tract?
In the context provided, what would be expected if there is damage to the Medullary (Lateral) Reticulospinal Tract?
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Which statement accurately describes the function of the Vestibulospinal Tracts?
Which statement accurately describes the function of the Vestibulospinal Tracts?
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What is the main role of the Rubrospinal Tracts in movement coordination?
What is the main role of the Rubrospinal Tracts in movement coordination?
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What would be the expected motor deficit if a lesion occurs above the pyramidal decussation?
What would be the expected motor deficit if a lesion occurs above the pyramidal decussation?
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In a patient with right-sided manifestations, why can a spinal cord lesion on the right side be ruled out?
In a patient with right-sided manifestations, why can a spinal cord lesion on the right side be ruled out?
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Where do fibers cross in the medulla for pain and thermal sensation?
Where do fibers cross in the medulla for pain and thermal sensation?
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Which tract carries fibers that primarily control voluntary, discrete, skilled movements?
Which tract carries fibers that primarily control voluntary, discrete, skilled movements?
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In a patient with contralateral loss of pain and thermal sensation below the lesion level, where is the site of the lesion most likely located?
In a patient with contralateral loss of pain and thermal sensation below the lesion level, where is the site of the lesion most likely located?
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What type of motor deficit would be expected in a patient with a lesion below the pyramidal decussation?
What type of motor deficit would be expected in a patient with a lesion below the pyramidal decussation?
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What type of fibers make up 75-90% of the lateral corticospinal tract?
What type of fibers make up 75-90% of the lateral corticospinal tract?
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What is the consequence of an occlusion of vessels supplying the area where CST fibers pass through?
What is the consequence of an occlusion of vessels supplying the area where CST fibers pass through?
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What would be the expected outcome if the vessel supplying the area where CST fibers pass through becomes occluded?
What would be the expected outcome if the vessel supplying the area where CST fibers pass through becomes occluded?
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Which tract controls arms, trunk, and lower limbs located at the posterior limb of the internal capsule?
Which tract controls arms, trunk, and lower limbs located at the posterior limb of the internal capsule?
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What distinguishes the anterior corticospinal tract from the lateral corticospinal tract regarding fiber crossing?
What distinguishes the anterior corticospinal tract from the lateral corticospinal tract regarding fiber crossing?
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Where do CST fibers controlling the upper limbs traverse within the internal capsule?
Where do CST fibers controlling the upper limbs traverse within the internal capsule?
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Where do fibers of the Corticobulbar Tract originate from?
Where do fibers of the Corticobulbar Tract originate from?
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What is the primary function of the Pons/Medulla Lateral Vestibulospinal Tract?
What is the primary function of the Pons/Medulla Lateral Vestibulospinal Tract?
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Which region do fibers of the Corticobulbar Tract project to, apart from motor nuclei of certain Cranial Nerves?
Which region do fibers of the Corticobulbar Tract project to, apart from motor nuclei of certain Cranial Nerves?
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Which type of fibers does the Medial Vestibulospinal Tract contain?
Which type of fibers does the Medial Vestibulospinal Tract contain?
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Where does the Medial Vestibulospinal Tract terminate within the spinal cord?
Where does the Medial Vestibulospinal Tract terminate within the spinal cord?
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Which area is essential for controlling facial muscles involved in emotional expressions, receiving projections from the Corticobulbar Tract?
Which area is essential for controlling facial muscles involved in emotional expressions, receiving projections from the Corticobulbar Tract?
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In addition to motor nuclei of certain Cranial Nerves, where else do fibers from the Corticobulbar Tract terminate?
In addition to motor nuclei of certain Cranial Nerves, where else do fibers from the Corticobulbar Tract terminate?
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What type of neurons does the Pons/Medulla Lateral Vestibulospinal Tract innervate?
What type of neurons does the Pons/Medulla Lateral Vestibulospinal Tract innervate?
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Which part of the brainstem or bulbar region receives the terminations of fibers from the Corticobulbar Tract?
Which part of the brainstem or bulbar region receives the terminations of fibers from the Corticobulbar Tract?
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What is the primary source of afferents for the Pons/Medulla Lateral Vestibulospinal Tract?
What is the primary source of afferents for the Pons/Medulla Lateral Vestibulospinal Tract?
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Which function is specific to the Medial Vestibulospinal Tract compared to the Lateral Vestibulospinal Tract?
Which function is specific to the Medial Vestibulospinal Tract compared to the Lateral Vestibulospinal Tract?
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A patient with a lesion of the left lateral funiculus of the lumbar segment of the spinal cord will present with weakness in which limb?
A patient with a lesion of the left lateral funiculus of the lumbar segment of the spinal cord will present with weakness in which limb?
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Which tract arising from the midbrain facilitates the activity of flexor muscle groups in response to visual stimuli?
Which tract arising from the midbrain facilitates the activity of flexor muscle groups in response to visual stimuli?
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Which part of the spinal cord do the extrapyramidal tracts arising from the midbrain cross before descending to terminate in the anterior gray horn?
Which part of the spinal cord do the extrapyramidal tracts arising from the midbrain cross before descending to terminate in the anterior gray horn?
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Which tract mediates reflex postural movements and is functionally similar to the Corticospinal Tract?
Which tract mediates reflex postural movements and is functionally similar to the Corticospinal Tract?
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Which tracts arising from the pons/medulla are responsible for facilitating indirect pathways in controlling muscle activity?
Which tracts arising from the pons/medulla are responsible for facilitating indirect pathways in controlling muscle activity?
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What is the primary function of the Rubrospinal Tract in movement coordination?
What is the primary function of the Rubrospinal Tract in movement coordination?
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What motor function would be affected by a lesion below the Pyramidal Decussation in the Medulla Oblongata?
What motor function would be affected by a lesion below the Pyramidal Decussation in the Medulla Oblongata?
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Where are the ventral CST fibers located within the spinal cord?
Where are the ventral CST fibers located within the spinal cord?
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Which part of the midbrain is primarily responsible for controlling the lower limbs?
Which part of the midbrain is primarily responsible for controlling the lower limbs?
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In a spinal cord lesion scenario, which side of the body would exhibit paralysis?
In a spinal cord lesion scenario, which side of the body would exhibit paralysis?
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What is the primary role of transverse pontocerebellar fibers within the Pons?
What is the primary role of transverse pontocerebellar fibers within the Pons?
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Which condition is most likely to result from a lesion affecting fibers above the Pyramidal Decussation?
Which condition is most likely to result from a lesion affecting fibers above the Pyramidal Decussation?
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In a patient with atrophied and deviated tongue to the RIGHT, what type of lesion is likely present?
In a patient with atrophied and deviated tongue to the RIGHT, what type of lesion is likely present?
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A patient with a stroke presenting with tongue deviation to the RIGHT but not atrophy most likely has a lesion in the:
A patient with a stroke presenting with tongue deviation to the RIGHT but not atrophy most likely has a lesion in the:
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What is the expected presentation of a patient with a stroke affecting the LEFT hypoglossal nucleus?
What is the expected presentation of a patient with a stroke affecting the LEFT hypoglossal nucleus?
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When observing a patient with tongue deviation to the RIGHT due to a LEFT hemisphere stroke, which motor neuron type is most likely affected?
When observing a patient with tongue deviation to the RIGHT due to a LEFT hemisphere stroke, which motor neuron type is most likely affected?
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A patient with inability to move the lower LEFT half of the face but can still wrinkle both eyebrows likely has a lesion in the:
A patient with inability to move the lower LEFT half of the face but can still wrinkle both eyebrows likely has a lesion in the:
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Which type of lesion would result in a presentation of tongue deviation to the ipsilateral side with atrophy?
Which type of lesion would result in a presentation of tongue deviation to the ipsilateral side with atrophy?
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What is the origin of the Rubrospinal Tract?
What is the origin of the Rubrospinal Tract?
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How do fibers of the Rubrospinal Tract reach the spinal cord?
How do fibers of the Rubrospinal Tract reach the spinal cord?
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What is the main function of the Rubrospinal Tract?
What is the main function of the Rubrospinal Tract?
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Where do the fibers of the Rubrospinal Tract terminate within the spinal cord?
Where do the fibers of the Rubrospinal Tract terminate within the spinal cord?
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What is the functional similarity between the Rubrospinal Tract and the Corticospinal Tract?
What is the functional similarity between the Rubrospinal Tract and the Corticospinal Tract?
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In what part of the spinal cord do the fibers of the Rubrospinal Tract enter for termination?
In what part of the spinal cord do the fibers of the Rubrospinal Tract enter for termination?
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Where would motor deficits be observed in a patient with a lesion below the pyramidal decussation?
Where would motor deficits be observed in a patient with a lesion below the pyramidal decussation?
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Which tract is responsible for contralateral loss of pain and thermal sensation below the level of the lesion?
Which tract is responsible for contralateral loss of pain and thermal sensation below the level of the lesion?
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In a patient with ipsilateral motor deficits, which type of lesion can be ruled out?
In a patient with ipsilateral motor deficits, which type of lesion can be ruled out?
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What is the significance of fibers crossing in the medulla for pain and thermal sensation?
What is the significance of fibers crossing in the medulla for pain and thermal sensation?
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What manifestation would be expected in a patient with a lesion above the pyramidal decussation?
What manifestation would be expected in a patient with a lesion above the pyramidal decussation?
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Which area would exhibit symptoms if there were a spinal cord lesion present?
Which area would exhibit symptoms if there were a spinal cord lesion present?
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A lesion in the RIGHT hypoglossal nucleus would manifest with which of the following neurologic findings?
A lesion in the RIGHT hypoglossal nucleus would manifest with which of the following neurologic findings?
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Where do Corticobulbar tract fibers pass through in the internal capsule?
Where do Corticobulbar tract fibers pass through in the internal capsule?
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If a lesion involves the LEFT Corticobulbar Tract projecting to the facial motor nucleus, which part of the face would experience weakness?
If a lesion involves the LEFT Corticobulbar Tract projecting to the facial motor nucleus, which part of the face would experience weakness?
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Which part of the internal capsule contains the corticospinal tract fibers?
Which part of the internal capsule contains the corticospinal tract fibers?
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A lesion involving the dorsolateral portion of the LEFT sensorimotor cortex would result in which neurologic manifestation?
A lesion involving the dorsolateral portion of the LEFT sensorimotor cortex would result in which neurologic manifestation?
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Where do corticospinal tract fibers pass through in the internal capsule?
Where do corticospinal tract fibers pass through in the internal capsule?
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Which grade of Deep Tendon Reflexes indicates a slight but definitely present response, which may or may not be normal?
Which grade of Deep Tendon Reflexes indicates a slight but definitely present response, which may or may not be normal?
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What is the characteristic feature of a 4+ Deep Tendon Reflex?
What is the characteristic feature of a 4+ Deep Tendon Reflex?
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What can be elicited in the flexor muscles of fingers, biceps, calf, and quadriceps muscles?
What can be elicited in the flexor muscles of fingers, biceps, calf, and quadriceps muscles?
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What characterizes an Upper Motor Neuron (UMN) lesion in relation to clonus?
What characterizes an Upper Motor Neuron (UMN) lesion in relation to clonus?
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How is the Babinski reflex elicited according to the text?
How is the Babinski reflex elicited according to the text?
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What is the primary function of the Supplementary Motor Area as described in the text?
What is the primary function of the Supplementary Motor Area as described in the text?
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If there is an occlusion in the Middle Cerebral Artery (MCA), what neurological manifestation is likely to be observed according to the text?
If there is an occlusion in the Middle Cerebral Artery (MCA), what neurological manifestation is likely to be observed according to the text?
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Which area of the cerebral hemisphere is represented by a blue circle in Figure 6 as described in the text?
Which area of the cerebral hemisphere is represented by a blue circle in Figure 6 as described in the text?
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What is a significant consequence of an occlusion in the Anterior Cerebral Artery (ACA) according to the text?
What is a significant consequence of an occlusion in the Anterior Cerebral Artery (ACA) according to the text?
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Which lobule is located at the most medial portion of BA 6, anterior to the Paracentral Lobule, as described in the text?
Which lobule is located at the most medial portion of BA 6, anterior to the Paracentral Lobule, as described in the text?
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What is a distinctive feature of the movements controlled by the Paracentral Lobule based on the information provided?
What is a distinctive feature of the movements controlled by the Paracentral Lobule based on the information provided?
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Which cortical areas give rise to fibers of the corticobulbar tract?
Which cortical areas give rise to fibers of the corticobulbar tract?
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Where do fibers of the corticobulbar tract terminate in the brainstem?
Where do fibers of the corticobulbar tract terminate in the brainstem?
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Which cranial nerves receive projections from the corticobulbar tract?
Which cranial nerves receive projections from the corticobulbar tract?
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Which structure receives corticoreticular fibers from the corticobulbar tract?
Which structure receives corticoreticular fibers from the corticobulbar tract?
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What is the primary function of the sensory relay nuclei that receive inputs from the corticobulbar tract?
What is the primary function of the sensory relay nuclei that receive inputs from the corticobulbar tract?
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What is a distinctive characteristic of fasciculations that makes them specific for LMN involvement?
What is a distinctive characteristic of fasciculations that makes them specific for LMN involvement?
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In a patient with symptoms of progressive muscular atrophy and paralysis, which type of neuron damage is likely occurring?
In a patient with symptoms of progressive muscular atrophy and paralysis, which type of neuron damage is likely occurring?
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Which condition would present with both upper motor neuron (UMN) and lower motor neuron (LMN) characteristics?
Which condition would present with both upper motor neuron (UMN) and lower motor neuron (LMN) characteristics?
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What distinguishes LMN from UMN involvement in terms of paresis presentation?
What distinguishes LMN from UMN involvement in terms of paresis presentation?
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Which symptom would be expected in a patient with amyotrophic lateral sclerosis (ALS) but not in poliomyelitis?
Which symptom would be expected in a patient with amyotrophic lateral sclerosis (ALS) but not in poliomyelitis?
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If a patient presents with multiple cranial nerve deficits ipsilateral to the lesion, where in the brainstem could the lesion be located?
If a patient presents with multiple cranial nerve deficits ipsilateral to the lesion, where in the brainstem could the lesion be located?
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In relation to motor deficits caused by a brainstem lesion, where are these deficits typically observed?
In relation to motor deficits caused by a brainstem lesion, where are these deficits typically observed?
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What type of facial deficit is typically associated with a UMN lesion in the brain?
What type of facial deficit is typically associated with a UMN lesion in the brain?
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In a patient who is drowsy with abnormal MSE but normal cranial nerves, what area of the cerebral cortex may be affected?
In a patient who is drowsy with abnormal MSE but normal cranial nerves, what area of the cerebral cortex may be affected?
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Where would a lesion need to occur to result in motor and sensory deficits on the same side of the body?
Where would a lesion need to occur to result in motor and sensory deficits on the same side of the body?
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If a patient were to have a lesion in the internal capsule affecting motor and sensory areas of the face and upper extremity, which symptoms would most likely be observed?
If a patient were to have a lesion in the internal capsule affecting motor and sensory areas of the face and upper extremity, which symptoms would most likely be observed?
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What is the primary role of the pyramidal decussations in the corticospinal tract?
What is the primary role of the pyramidal decussations in the corticospinal tract?
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What distinguishes the Medullary (Lateral) Reticulospinal Tract from the Pontine Reticulospinal Tract?
What distinguishes the Medullary (Lateral) Reticulospinal Tract from the Pontine Reticulospinal Tract?
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In a patient with a lesion involving the Spinal cord ventral CST, what paralysis would be expected?
In a patient with a lesion involving the Spinal cord ventral CST, what paralysis would be expected?
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What type of motor deficit would be observed in a patient with a lesion affecting the Corticospinal Tract fibers above the pyramidal decussation?
What type of motor deficit would be observed in a patient with a lesion affecting the Corticospinal Tract fibers above the pyramidal decussation?
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How do lesions within the cerebral cortex above the pyramidal decussations typically affect motor functions?
How do lesions within the cerebral cortex above the pyramidal decussations typically affect motor functions?
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Where are the fibers of the lateral CST located within the spinal cord?
Where are the fibers of the lateral CST located within the spinal cord?
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What type of paralysis is typically seen in a patient with an Upper Motor Neuron lesion?
What type of paralysis is typically seen in a patient with an Upper Motor Neuron lesion?
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Which type of paralysis involves one limb only?
Which type of paralysis involves one limb only?
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What is the primary difference in muscle tone between Upper Motor Neuron and Lower Motor Neuron lesions?
What is the primary difference in muscle tone between Upper Motor Neuron and Lower Motor Neuron lesions?
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Which term describes the condition where unused muscle shrinks over time due to lack of therapy or exercise?
Which term describes the condition where unused muscle shrinks over time due to lack of therapy or exercise?
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Which lesion type is associated with early muscle atrophy due to damage to anterior horn cells?
Which lesion type is associated with early muscle atrophy due to damage to anterior horn cells?
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What is a distinguishing characteristic of Lower Motor Neuron lesions compared to Upper Motor Neuron lesions?
What is a distinguishing characteristic of Lower Motor Neuron lesions compared to Upper Motor Neuron lesions?
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What is the term used to describe a lesion at the left sensory motor cortex face area or corticobulbar tract fibers?
What is the term used to describe a lesion at the left sensory motor cortex face area or corticobulbar tract fibers?
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In Central Facial Paralysis, what part of the face is affected by the lesion?
In Central Facial Paralysis, what part of the face is affected by the lesion?
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What is the characteristic paralysis seen in Peripheral Facial Paralysis?
What is the characteristic paralysis seen in Peripheral Facial Paralysis?
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Which cranial nerve deficit pattern is typically observed in a patient with Central Facial Paralysis?
Which cranial nerve deficit pattern is typically observed in a patient with Central Facial Paralysis?
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What distinguishes Bell's Palsy from Central Facial Paralysis?
What distinguishes Bell's Palsy from Central Facial Paralysis?
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What is the expected result of a lesion affecting the ventral portion of the Corticobulbar Tract?
What is the expected result of a lesion affecting the ventral portion of the Corticobulbar Tract?
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What is the primary distinguishing feature between the presentation of progressive muscular atrophy in upper motor neuron (UMN) and lower motor neuron (LMN) involvement?
What is the primary distinguishing feature between the presentation of progressive muscular atrophy in upper motor neuron (UMN) and lower motor neuron (LMN) involvement?
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If a patient initially presents with weakness due to destruction of neurons in the anterior gray horn, what will be the eventual outcome once the neurons are completely destroyed?
If a patient initially presents with weakness due to destruction of neurons in the anterior gray horn, what will be the eventual outcome once the neurons are completely destroyed?
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What would be a specific symptom observed in both upper motor neuron (UMN) and lower motor neuron (LMN) involvement in poliomyelitis?
What would be a specific symptom observed in both upper motor neuron (UMN) and lower motor neuron (LMN) involvement in poliomyelitis?
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In the context of spinal cord injuries, what manifestation indicates that not all injuries would present with lower motor neuron (LMN) features?
In the context of spinal cord injuries, what manifestation indicates that not all injuries would present with lower motor neuron (LMN) features?
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Which condition specifically presents with a slow destruction of the anterior horn cells leading to characteristics such as paresis and fasciculations?
Which condition specifically presents with a slow destruction of the anterior horn cells leading to characteristics such as paresis and fasciculations?
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What is the primary function attributed to the Pontine (Medial) Reticulospinal Tract?
What is the primary function attributed to the Pontine (Medial) Reticulospinal Tract?
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Where do fibers of the Medial Vestibulospinal Tract terminate within the spinal cord?
Where do fibers of the Medial Vestibulospinal Tract terminate within the spinal cord?
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Which region serves as the origin of the 1st order neuron in the corticospinal tract?
Which region serves as the origin of the 1st order neuron in the corticospinal tract?
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What distinguishes between the functions of the Medullary Reticulospinal Tract and the Pontine Reticulospinal Tract?
What distinguishes between the functions of the Medullary Reticulospinal Tract and the Pontine Reticulospinal Tract?
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What is distinctive about the manifestation of extrapyramidal tracts compared to pyramidal tracts based on the provided information?
What is distinctive about the manifestation of extrapyramidal tracts compared to pyramidal tracts based on the provided information?
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Which function can be influenced by the Medullary Reticulospinal Tract but not by the Pontine Reticulospinal Tract?
Which function can be influenced by the Medullary Reticulospinal Tract but not by the Pontine Reticulospinal Tract?
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What is the primary role of the 1st order neuron in the descending pathway?
What is the primary role of the 1st order neuron in the descending pathway?
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Which component is essential for a reflex to occur without requiring processing from higher centers?
Which component is essential for a reflex to occur without requiring processing from higher centers?
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What distinguishes the axon of the 3rd order neuron in the descending pathway from that of the 1st order neuron?
What distinguishes the axon of the 3rd order neuron in the descending pathway from that of the 1st order neuron?
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Which is a characteristic feature of the pyramidal tract?
Which is a characteristic feature of the pyramidal tract?
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What would be the consequence of damage to the 2nd order neuron in the descending pathway?
What would be the consequence of damage to the 2nd order neuron in the descending pathway?
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What is a key function of the Rubrospinal Tract in movement coordination?
What is a key function of the Rubrospinal Tract in movement coordination?
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What is a characteristic symptom specific to Lower Motor Neuron (LMN) involvement in the context of amyotrophic lateral sclerosis?
What is a characteristic symptom specific to Lower Motor Neuron (LMN) involvement in the context of amyotrophic lateral sclerosis?
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In the context of spinal cord injuries, what manifestation would suggest damage to the anterior gray column of the spinal cord?
In the context of spinal cord injuries, what manifestation would suggest damage to the anterior gray column of the spinal cord?
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Which motor neuron condition is characterized by a slow destruction of the anterior horn cells resulting in paresis and fasciculations?
Which motor neuron condition is characterized by a slow destruction of the anterior horn cells resulting in paresis and fasciculations?
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If only the tracts were affected due to a spinal cord injury, which manifestation would be evident?
If only the tracts were affected due to a spinal cord injury, which manifestation would be evident?
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What symptom is typically seen when both Upper Motor Neuron (UMN) and Lower Motor Neuron (LMN) conditions coexist?
What symptom is typically seen when both Upper Motor Neuron (UMN) and Lower Motor Neuron (LMN) conditions coexist?
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What is the clinical presentation that distinguishes an Upper Motor Neuron lesion from a Lower Motor Neuron lesion?
What is the clinical presentation that distinguishes an Upper Motor Neuron lesion from a Lower Motor Neuron lesion?
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What type of paralysis is typically seen in Monoplegia?
What type of paralysis is typically seen in Monoplegia?
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Which manifestation would be indicative of a lesion involving the Medullary Reticulospinal Tract?
Which manifestation would be indicative of a lesion involving the Medullary Reticulospinal Tract?
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In paralysis due to a lesion above the pyramidal decussation, what would be expected regarding limb involvement?
In paralysis due to a lesion above the pyramidal decussation, what would be expected regarding limb involvement?
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What factor contributed to the re-emergence of polio cases in the Philippines despite being declared polio-free by WHO?
What factor contributed to the re-emergence of polio cases in the Philippines despite being declared polio-free by WHO?
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Which area of the body would experience weakness if the LEFT Corticobulbar Tract projecting to the facial motor nucleus is affected?
Which area of the body would experience weakness if the LEFT Corticobulbar Tract projecting to the facial motor nucleus is affected?
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What is the normal response to a scratch or stroke on the abdominal muscles to elicit the superficial abdominal reflex?
What is the normal response to a scratch or stroke on the abdominal muscles to elicit the superficial abdominal reflex?
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Which cranial nerve nucleus is located close to the midline at the dorsal portion of the pons?
Which cranial nerve nucleus is located close to the midline at the dorsal portion of the pons?
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What is a characteristic of an UMN lesion with regard to the cremasteric reflex?
What is a characteristic of an UMN lesion with regard to the cremasteric reflex?
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Where does the hypoglossal nucleus (CN XII) span along in the brainstem?
Where does the hypoglossal nucleus (CN XII) span along in the brainstem?
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What is a common presentation in LMN lesions regarding muscle fasciculations?
What is a common presentation in LMN lesions regarding muscle fasciculations?
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In an UMN lesion, what would be observed regarding the superficial abdominal reflex?
In an UMN lesion, what would be observed regarding the superficial abdominal reflex?
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Which artery supplies the area of the face and upper extremities?
Which artery supplies the area of the face and upper extremities?
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In which part of the internal capsule do fibers of the corticospinal tract to the lower extremities pass through?
In which part of the internal capsule do fibers of the corticospinal tract to the lower extremities pass through?
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What symptoms would a patient exhibit if there is a lesion in the left sensorimotor cortex involving loss of pain, thermal sensation, and decreased vibratory sensation on the right side?
What symptoms would a patient exhibit if there is a lesion in the left sensorimotor cortex involving loss of pain, thermal sensation, and decreased vibratory sensation on the right side?
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Which area would likely be affected if there is an occlusion of the vessel supplying the middle cerebral artery (MCA)?
Which area would likely be affected if there is an occlusion of the vessel supplying the middle cerebral artery (MCA)?
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What distinguishes a cortical lesion from a lesion in the internal capsule?
What distinguishes a cortical lesion from a lesion in the internal capsule?
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What characterizes a lesion involving loss of pain, thermal sensation, and decreased vibratory sensation?
What characterizes a lesion involving loss of pain, thermal sensation, and decreased vibratory sensation?
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Study Notes
Here are the study notes:
Motor Neuron Lesions
- Motor neuron lesions can be classified into two types: Upper Motor Neuron (UMN) lesions and Lower Motor Neuron (LMN) lesions.
Upper Motor Neuron (UMN) Lesions
- Characteristics:
- No muscle atrophy initially
- If patient cannot exercise or have therapy, may develop disuse atrophy
- Spasticity in muscle tone
- Hyperreflexia
- Clonus present
- Babinski reflex present
- Loss of certain superficial reflexes (e.g. superficial abdominal reflex, cremasteric reflex)
Lower Motor Neuron (LMN) Lesions
- Characteristics:
- Muscle atrophy early on
- Flaccidity in muscle tone
- Areflexia (absence of reflexes)
- No clonus
- No Babinski reflex
- Fasciculations (twitching of muscle)
Corticospinal Tract
- A descending tract responsible for the primary control of voluntary movement
- Divided into two main tracts:
- Corticospinal tract: pathways for voluntary, discrete, skilled movements
- Corticobulbar tract: pathways for voluntary movements of the face, tongue, and pharynx
Pyramidal Tract
- Originates from the primary motor cortex and premotor cortex
- Fibers pass through the internal capsule, crus cerebri, pons, and medulla oblongata
- Forms the pyramids in the medulla oblongata
- Fibers cross at the pyramidal decussation and form the lateral corticospinal tract
- Lesions above the pyramidal decussation affect contralateral regions, while lesions below affect ipsilateral regions
Corticobulbar Tract
- Originates from the primary motor cortex and premotor cortex
- Fibers pass through the internal capsule, crus cerebri, and pons
- Controls voluntary movements of the face, tongue, and pharynx
Reflex Arc
- A reflex arc consists of:
- Receptor organ
- Afferent neuron
- Efferent neuron
- Effector organ
- Damage to any of these components would abolish the reflex### Motor Homunculus
- Representations of the body on the primary motor and premotor cortex
- Each part of the body is represented on a specific portion of the primary and premotor cortex
- Tongue and larynx: lowest lateral portion close to the Sylvian fissure
- Lips and face: ventral
- Fingers and hands: dorsolateral
- Arms and trunk: superior
- Perineal muscles, legs, and feet: medial
Precentral Gyrus (BA 4)
- Primary motor cortex
- Functional area: 1/3 of the axons of the pyramidal tract arise
- Pyramidal cells of Betz:
- Give rise to 10% of precentral gyrus or 3% of entire corticospinal tract
- Located at the 5th layer of the cortical surface
- Send their axons directly to the anterior horn cells in the spinal cord
- Responsible for highly-skilled movements
Paracentral Lobule
- Area surrounding the central sulcus
- Represents lower limbs in the motor homunculus
- Comprises of:
- BA 4
- BA 3, 1, 2
- BA 5
Clinical Correlation
- Anterior cerebral artery (ACA): supplies the medial portions of the cerebral hemispheres
- Occlusion: result in weakness in the lower extremities
- Middle cerebral artery (MCA): supplies the dorsal and lateral portions of the cerebral hemispheres
- Occlusion: result in weakness in the face and upper extremities
Supplementary Motor Area
- Located in the medial frontal gyrus on the medial surface of the hemisphere
- Plays a special role in integrating movements that are performed simultaneously on both sides of the body
- Stimulation results in contralateral limb movement
- Needs a stronger stimulus than primary motor area
Corticospinal Tract
- A descending tract responsible for the primary control of voluntary movement
- Pathways for voluntary, discrete, skilled movements
- Uncrossed fibers (10-15%): eventually cross before terminating on the anterior horn
- Crossed fibers (75-90%): form pyramidal decussations terminating on the anterior horn
Extrapyramidal System
- Plays a supporting role in the production of well-coordinated movements
- Includes:
- Basal ganglia (nuclei)
- Cerebellum
Pyramidal Tract
- Responsible for the primary control of voluntary movement
- Carried out through two main tracts:
- Corticospinal tract
- Corticobulbar tract
Motor Neuron Lesions
- Upper motor neuron (UMN) lesion:
- Weakness or paralysis of the affected limb
- Reflexes are usually increased
- Lower motor neuron (LMN) lesion:
- Weakness or paralysis of the affected limb
- Reflexes are usually decreased or absent
Corticobulbar Tract
- Origin: cerebral cortex
- Destination: bulbar region or brainstem
- Arises from face region of primary motor cortex (BA 4), premotor (BA 6), frontal eye fields (BA 8)
- Fibers project to:
- Motor nuclei of CNs III, IV, V, VI, VII, IX, X, XI & XII
- Parts of reticular formation (corticoreticular fibers) in pons & medulla
- Sensory relay nuclei (gracilis, cuneatus, sensory trigeminal nuclei, & nucleus of solitary fasciculus)
Rubrospinal Tract
- Origin: red nucleus
- Fibers: crossed
- Termination: internuncial neurons in all spinal cord segments
- Function: facilitates the activity of flexor muscle groups, functionally similar to the CST
Reticulospinal Tracts
-
- Pontine (medial) reticulospinal tract:
- Origin: pons
- Fibers: almost entirely ipsilateral
- Termination: Lamina VII & VIII
- Function: facilitatory to extensor motor neurons
-
- Medullary (lateral) reticulospinal tract:
- Origin: medulla
- Fibers: both crossed and uncrossed
- Termination: Lamina VII & IX
- Function: inhibitory to extensor motor neurons
Vestibulospinal Tracts
-
- Lateral vestibulospinal tract:
- Origin: lateral vestibular nucleus
- Termination: Rexed Laminae VII & VIII
- Fibers: uncrossed
- Afferents: from vestibular nerve and cerebellum
- Function: maintenance of upright posture and balance
-
- Medial vestibulospinal tract:
- Origin: medial vestibular nucleus
- Termination: same laminae as the lateral vestibulospinal tract
- Fibers: both crossed and uncrossed
- Afferents: from primary vestibular and cerebellum
- Function: maintenance of upright postureHere are the study notes for the text:
Mental Status Exam (MSE)
- Patient is drowsy but arousable, speaks very slowly and with effort
- Motor strength of 2/5 over the right upper extremity
Pyramidal Tracts
- Ipsilateral loss of motor function → Fibers below the pyramidal decussation
- If the lesion is above the pyramidal decussation, it would produce loss of motor function contralateral to the side of the lesion
- Contralateral loss of pain and thermal sensation below the level of the lesion → Fibers in lateral funiculus (of the lateral spinothalamic tract) are axons of N2 which have already crossed
Spinal Cord Injuries
- UMN (Upper Motor Neuron) lesions: If only the tracts were affected
- LMN (Lower Motor Neuron) lesions: If the lesion was on the anterior gray column of the spinal cord, anterior horn cells will be damaged
- Poliomyelitis: It could be upper or lower manifestation → NOT all spinal cord injuries would present with LMN manifestations
- Amyotrophic Lateral Sclerosis (Lou Gehrig Disease): A progressive neurological disease that affects the motor neurons
Brainstem Lesions
- With CN deficits (nerves exit ipsilateral to their symptoms) → Midbrain: CN III → Pons: CN V, VI, VII → Medulla: CN IX, XI, XII
- Clue if brainstem lesion is present → Multiple cranial nerve deficits (ipsilateral)
- Deficits → CN deficits: Ipsilateral to the lesion → Motor deficits: Contralateral to the lesion
Corticobulbar Tract
- Origin: Cerebral cortex
- Destination: Bulbar region or brainstem
- Arises from face region of primary motor cortex (BA 4), premotor (BA 6), frontal eye fields (BA 8)
- Fibers would pass through the corona radiata, genu of the internal capsule, and terminate in the brainstem
- Fibers would project to: → Motor nuclei of CNs III, IV, V, VI, VII, IX, X, XI & XII
- Exceptions are I, II, and VIII which are purely sensory
Motor Neuron Lesions
- Moves muscle group with full resistance
- Muscle Atrophy:
- UMN lesion: No muscle atrophy initially; if the patient will not be able to have therapy or exercise, may develop disuse atrophy
- LMN lesion: With muscle atrophy early on; due to damage to anterior horn cells which have give nutrition to the muscles they innervate (trophic effect)
Rubrospinal Tract
- "Rubro" = "red"
- Origin: Red nucleus (at the level of superior colliculus)
- Fibers: → Cross immediately in the ventral tegmental decussation → Descend down the brainstem → Enter lateral funiculus of spinal cord
- Termination: → Internuncial neurons (anterior gray column) in all spinal cord levels (Lamina V, VI, VII)
- Function: → Influence tone control/facilitates the activity of flexor muscle groups → Functionally similar to the CST; said to assist the CST in its function
Clinical Correlation
- Anterior cerebral artery (ACA) → Supplies the medial portions of the cerebral hemispheres → Occlusion: result to weakness in the lower extremities
- Middle cerebral artery (MCA) → Supplies the dorsal and lateral portions of the cerebral hemispheres → Occlusion: result to weakness in the face and upper extremities
Pons/Medulla
- Lateral Vestibulospinal Tract:
- Origin: Lateral vestibular nucleus
- Termination: → Descends in anterolateral funiculus and terminates in Rexed Laminae VII & VIII on alpha & gamma motor neurons from cervical and lumbosacral levels
- Function: → Maintenance of upright posture and balance → Excites extensor motor neurons innervating the neck, back, forelimb, and hindlimb muscles
- Medial Vestibulospinal Tract:
- Origin: Medial vestibular nucleus
- Termination: → Descends in MLF → Anterior funiculus (as far as mid-thoracic level) → Terminates in the same laminae as the Lateral Vestibulospinal Tract (Rexed Laminae VII & VIII)
- Function: → Maintains upright posture → Excites the neck up to the back motor neurons only
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Description
Test your knowledge on pyramidal and extrapyramidal tracts in the motor system with this anatomy quiz. Topics covered include corticospinal, corticobulbar, and extrapyramidal tracts along with associated motor neuron lesions and CNS circuitry.
