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47 Cards in this Set

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  • Back

Which structures regulate the motor circuits in the spinal cord?

- Cortical structures
- Subcortical structures
- Brainstem
Which cortical structures regulate the motor circuits in the spinal cord?
- Primary Motor Cortex
- Prefrontal Cortex
- Somatosensory and Parietal Association Cortex
Which subcortical structures regulate the motor circuits in the spinal cord?
- Basal Ganglia
- Cerebellum
- Thalamus
What are the types of movement?
- Reflexes - stereotyped responses to stimuli
- Voluntary - goal-directed, internally generated, improve with practice
- Automatic Postural Adjustments
What are the two main systems of the motor pathways?
- Lateral Motor Pathways
- Medial Motor Pathways
What is the function of the lateral motor pathways?
Goal-directed limb movements
What tracts contain the fibers for the lateral motor pathways?
- Lateral Corticospinal Tract
- Rubrospinal Tract
What is the function of the medial motor pathways?
- Postural movements
- Head and neck movements
- Eye movements
What tracts contain the fibers for the medial motor pathways?
- Anterior Corticospinal Tract
- Vestibulospinal Tract
- Reticulospinal Tract
- Tectospinal Tract
What is the organization of the Primary Motor Cortex (MI)?
- Legs medial
- Head and tongue most lateral
- Structures used for tasks requiring great precision (e.g., hands, face) have disproportionately larger representations of motor cortex
- Legs medial
- Head and tongue most lateral
- Structures used for tasks requiring great precision (e.g., hands, face) have disproportionately larger representations of motor cortex
What ist he approximate location of a cortical lesion in a patient who exhibits facial weakness?
Lateral cortical surface
Lateral cortical surface
What artery supplies the leg area of M-1 and most of Supplementary Motor Area (SMA)?
ACA - Anterior Cerebral Artery
What artery supplies the trunk, hand, and face area of M-1 and the PMA?
MCA - Middle Cerebral Artery
What are some characteristics of the motor map of the primary motor cortex?
- Overlap
- Plasticity (can change with use or disuse of a particular body part)
What tract connects the Primary Motor Cortex to the alpha lower motor neurons that innervate a particular skeletal muscle?
Corticospinal Tract (CST) / Pyramidal Tracts
What are the functions of the Corticospinal Tract?
- Descends to all levels of the spinal cord for VOLUNTARY control of motor neurons that innervate muscles in DISTAL extremities
- Allows for skilled movements
- Excites flexor muscles, inhibits extensor muscles
Where do the Corticospinal Tract axons arise from?
- Primary motor cortex (~33%)
- Betz cells (large pyramidal neurons in lamina V of precentral gyrus) ~3%
- Premotor cortex and Supplementary Motor Area (~33%)
- Parietal lobe (~33%)
What structures do the Corticospinal Tract axons pass through on their way to the spinal cord?
- Corona Radiata
- Posterior Limb of Internal Capsule (between caudate and globus pallidus) 
- Middle of the Cerebral Peduncles (Crus Cerebri)
- Medullary Pyramids - decussate at pyramidal decussation
- Corona Radiata
- Posterior Limb of Internal Capsule (between caudate and globus pallidus)
- Middle of the Cerebral Peduncles (Crus Cerebri)
- Medullary Pyramids - decussate at pyramidal decussation
What are the two components of the Corticospinal Tract? How do they differ?
- Lateral CST - 90% of fibers decussate in pyramidal decussation and descend in lateral funiculus to all spinal cord levels
- Anterior/Ventral CST - 10% of fibers do NOT decussate in pyramids, but descend in anterior funiculus and decussate in ventral white commissure to thoracic spinal cord
Which side of the body do lesions of the Lateral Corticospinal Tract occur on?
- Above pyramidal decussation results in contralateral weakness
- Below pyramidal decussation results in ipsilateral weakness
- Above pyramidal decussation results in contralateral weakness
- Below pyramidal decussation results in ipsilateral weakness
What symptoms occur if the UMN is lesioned in the Corticospinal Tract?
- Paresis (weakness) or paralysis
- Spasticity (increased muscle tone)
- Hyperreflexia
- Loss of abdominal reflexes
- Babinski sign
- Above medulla - contralateral
- Below medulla - ipsilateral
What symptoms occur if the LMN is lesioned in the Corticospinal Tract?
- Muscle atrophy
- Fasciculations
- Hypotonia
- Hyporeflexia
What is lesioned if there is paresis (weakness) of a particular body part on one side?
Lesion in CONTRALATERAL cortex corresponding to area of cortical damage for Corticospinal Tract
Lesion in CONTRALATERAL cortex corresponding to area of cortical damage for Corticospinal Tract
What is lesioned if there is a hemiplegia (paralysis)?
Lesion in the CONTRALATERAL Posterior Limb of Internal Capsule
Lesion in the CONTRALATERAL Posterior Limb of Internal Capsule
What is lesioned if there is paralysis of lower face, tongue, arm, and leg as well as oculomotor palsy on the opposite side? What could cause this?
- Lesion in Cerebral Peduncle to Corticospinal Tract and CN III on same side as oculomotor palsy (contralateral to paralysis of face/tongue/arm/leg)
- Occlusion of PCA possibly
* Weber Syndrome *
- Lesion in Cerebral Peduncle to Corticospinal Tract and CN III on same side as oculomotor palsy (contralateral to paralysis of face/tongue/arm/leg)
- Occlusion of PCA possibly
* Weber Syndrome *
What is lesioned if there is hemiparesis of arm and leg (face is spared), with paralysis and atrophy of tongue on opposite side, with same side loss of touch, vibration and joint position sensation from half of body? Possible cause?
* Medial Medullary Syndrome * (on side tongue is pointing to)
- Lesion to Corticospinal Tract - contralateral to hemiparesis
- Lesion to CN XII - ipsilateral paralysis/atrophy
- Lesion to Medial Lemnisucs - contralateral to loss of sensation
- Possibl
* Medial Medullary Syndrome * (on side tongue is pointing to)
- Lesion to Corticospinal Tract - contralateral to hemiparesis
- Lesion to CN XII - ipsilateral paralysis/atrophy
- Lesion to Medial Lemnisucs - contralateral to loss of sensation
- Possibly caused by occlusion of Vertebral A. or Anterior Spinal A.
What is lesioned if there is spastic paralysis and Babinski sign on the same side?
Corticospinal Tract lesion in the spinal cord (UMN)
Corticospinal Tract lesion in the spinal cord (UMN)
What are the symptoms of a lesion in the cortex that affects the Corticospinal Tract?
Contralateral paresis of a particular body part corresponding to the area of cortical damage
Contralateral paresis of a particular body part corresponding to the area of cortical damage
What are the symptoms of a lesion in the Posterior Limb of the Internal Capsule?
Contralateral Hemiplegia
Contralateral Hemiplegia
What are the symptoms of a lesion in the Cerebral Peduncle? Name? Cause?
- Corticospinal tract --> contralateral paralysis of lower face, tongue, arm, and leg
- CN III --> ipsilateral oculomotor palsy (eyes deviate laterally, ptosis, pupil is dilated and fixed)
* Weber Syndrome * 
- Occlusion of PCA
- Corticospinal tract --> contralateral paralysis of lower face, tongue, arm, and leg
- CN III --> ipsilateral oculomotor palsy (eyes deviate laterally, ptosis, pupil is dilated and fixed)
* Weber Syndrome *
- Occlusion of PCA
What can cause Weber Syndrome?
Occlusion of PCA
Occlusion of PCA
What are the symptoms of a lesion in the Medullary Pyramid? Name? Cause?
- Corticospinal tract --> contralateral hemiparesis of arm and leg (face is spared)
- CN XII --> ipsilateral paralysis and atrophy of tongue (points to injured side)
- Medial lemniscus --> contralateral loss of touch, vibration, and joint position from
- Corticospinal tract --> contralateral hemiparesis of arm and leg (face is spared)
- CN XII --> ipsilateral paralysis and atrophy of tongue (points to injured side)
- Medial lemniscus --> contralateral loss of touch, vibration, and joint position from half of body
* Medial Medullary Syndrome
- Occlusion of vertebral a. or anterior spinal a.
What can cause Medial Medullary Syndrome?
Occlusion of vertebral a. or anterior spinal a.
Occlusion of vertebral a. or anterior spinal a.
What are the symptoms of a lesion in the spinal cord to the Corticospinal Tract?
- Ipsilateral spastic paralysis
- Ipsilateral Babinski sign
- Ipsilateral spastic paralysis
- Ipsilateral Babinski sign
Why is CN III affected in Weber Syndrome?
CN III is leaving the midbrain and leaves via the interpeduncular region between the crux cerebri; can be injured since this is a lesion to the cerebral peduncle
CN III is leaving the midbrain and leaves via the interpeduncular region between the crux cerebri; can be injured since this is a lesion to the cerebral peduncle
Why is CN XII affected in Medial Medullary Syndrome?
CN XII is leaving the medulla between the pyramids and the olives and can be injured
What is the route of the Rubrospinal Tract in non-human primates and other mammals?
- Large (magnocellular) neurons in red nucleus send out axons which:
1) decussate in ventral tegmentum
2) descend in the lateral funiculus
3) terminate in lateral regions of the ventral horn at cervical spinal cord levels (control distal extremities)
- Large (magnocellular) neurons in red nucleus send out axons which:
1) decussate in ventral tegmentum
2) descend in the lateral funiculus
3) terminate in lateral regions of the ventral horn at cervical spinal cord levels (control distal extremities)
What is the function of the Rubrospinal Tract in non-human primates and other animals?
Presumably, contributes to control of forelimbs and paws (arms)
Why is the Rubrospinal Tract less important in humans?
- Few, if any, magnocellular neurons exit the red nucleus (these are the neurons for this tract)
- Few, if any, magnocellular neurons exit the red nucleus (these are the neurons for this tract)
What kind of neurons, in a human, leave the red nucleus? Where do they project to?
- Small (parvocellular) neurons in red nucleus
- Project to inferior olive
- Inferior olivary nucleus sends input to cerebellum (Olivo-Cerebellar Tract)
- Sends axons back to thalamus and collaterals to red nucleus (feedback loop)
What is the path of the Olivo-Cerebellar Tract? Function?
- Small (parvocellular) neurons in red nucleus
- Project to inferior olive
- Inferior olivary nucleus sends input to cerebellum (Olivo-Cerebellar Tract)
* Function: participates in learning and memory functions of cerebellum
- Also sends collateral axons to red nucleus in feedback loop for adaptation of cerebellar circuits
What kind of lesion causes the patient to exhibit flexed upper limbs at elbow and extended lower limbs?
What kind of lesion causes the patient to exhibit flexed upper limbs at elbow and extended lower limbs?
- Upper Midbrain damage --> decorticate posturing / rigidity 
- Transection of brainstem rostral to superior colliculus causes:
- Elimination of cortical input to red nucleus
- Cerebellar input to red nucleus is intact
- Rubrospinal tract is intact
- Upper Midbrain damage --> decorticate posturing / rigidity
- Transection of brainstem rostral to superior colliculus causes:
- Elimination of cortical input to red nucleus
- Cerebellar input to red nucleus is intact
- Rubrospinal tract is intact
What kind of lesion causes the patient to exhibit extension of both upper and lower limbs/
What kind of lesion causes the patient to exhibit extension of both upper and lower limbs/
Lower Midbrain damage --> decerebrate posturing
Lower Midbrain damage --> decerebrate posturing
What happens if there is a lesion to the upper midbrain (rostral to superior colliculus)?
What happens if there is a lesion to the upper midbrain (rostral to superior colliculus)?
- Flexion of upper limbs at elbow
- Lower limbs extended
- Caused by loss of cortical input to red nucleus
- Flexion of upper limbs at elbow
- Lower limbs extended
- Caused by loss of cortical input to red nucleus
What happens if there is a lesion to the lower midbrain?
What happens if there is a lesion to the lower midbrain?
Extension of both upper and lower limbs
Extension of both upper and lower limbs
What is lesioned if a patient has ipsilateral oculomotor palsy and a contralateral tremor? Name?
Unilateral lesion of red nucleus = Benedikt's syndrome
Unilateral lesion of red nucleus = Benedikt's syndrome
What are the symptoms of a unilateral lesion of the red nucleus?
- CN III injury --> ipsilateral oculomotor palsy (eye deviates laterally, ptosis, pupil is fixed and dilated)
- Contralateral tremor
- CN III injury --> ipsilateral oculomotor palsy (eye deviates laterally, ptosis, pupil is fixed and dilated)
- Contralateral tremor