Supraspinal Motor Control Flashcards
supraspinal motor control is carried out at multiple levels of the ( ) and is conveyed to the cord via the ( )
- brainstem and cerebral cortex
- descending pathways
the descending pathways can be divided into ( )
medial and lateral pathways
which pathways are phylogenetically older?
medial pathways
which pathways are more likely uncrossed or bilateral projecting pathways?
medial
medial pathways have more to do with ( ) of posture and balance
extensors and axial and proximal muscle control
which pathways include vestibulospinal, descending medial longitudinal fasciculus and reticulospinal pathways
medial pathways
which pathways are largely crossed pathways that control flexors and more distal muscules for fine motor control?
lateral pathways
which pathways include the rubrospinal tract and the lateral corticospinal tract?
lateral pathways
which tracts are lateral systems in terms of physiology but are physically located medially in the neuroaxis?
tectospinal and medial corticospinal tracts
the vestibulospinal tract originates largely in the ( ) and descends ( ) through the brainstem and ventromedial spinal cord to influence ( )
- lateral vestibular nucleus
- ipsilaterally
- extensor alpha motoneuron pools
this pathways serves to connect the spinal motor system with vestibular and cerebellar input, clearly proving the cord with info regarding balance
vestibulospinal tract
the descending portion of the ( ) originates in the medial vestibular nucleus and descends through the thoracic cord bilaterally
medial longitudinal fasciculus (MLF)
the ( ) has cells of origin in both the pontine and medullary reticular formations
reticulospinal tract
the potine reticular formation gives rise to the ( ) and is excitatory to ( )
- ipsilateral medial reticulospinal tract
- extensor gamma motoneurons
the meduallary reticular formation gives rise to the ( ) and is inhibitory to ( )
- ipsilateral lateral reticulospinal tract
- extensor gamma motoneurons
medullary reticular formation recieves excitatory input from the ( ) while the potine reticular formation recieves exitatory input from ( )
- cerebral cortex
- ascending spinoreticular sources in addition to cortical input
the ( ) originates in the contralateral red nucleus and probably only projects through the cervical spinal cord
rubrospinal tract
in ( ), the rubrospinal system carries out much of what has been taken over by the corticospinal tract in humans
phylogenetically lower species
the rubrospinal tract provides excitatory input to ( ) of the upper extremity
flexor motoneuron pools
the ( ) originates in the deep layers of the contralateral superior colliculus
tectospinal tract
tectospinal tract projects only to ( )
cervical levels of the spinal cord
as the superior colliculus receives visual input, it is thought that the ( ) allows for head and trunk positioning in response to visual stimulus
tectospinal tract
while tectospinal tract is crossed, it projects medial in the ( ) and to ( )
cord; proximal motoneuron pools
which tract sends projections from several areas of cerebral cortex to spinal motoneurons and brainstem nuclei (predominantly those innervating FLEXOR and DISTAL muscles involved in fine motor skills)
the corticospinal (and corticobulbar) tract
lesions in the ( ) affect the execution of fine motor skills while leaving motor strength relatively more preserved
cerebral cortex
the areas of cerebral cortex involved in motor planning and execution send their commands to the spinal cord directly through the ( ) and indirectly through the ( )
- corticospinal tract
- reticular formation and red nucleus
between 30-40% of corticospinal fibers originate in ( ) to modulate sensorimotor function within the spinal cord
primary sensory cortex
the majority of corticospinal fibers cross the midline at the level of the ( ) and descend as the ( ) but a few travel in the cord ipsilaterally as ventral corticospinal tract only to terminate bilaterally in the cord
- pyramidal decussation in the medulla
- lateral corticospinal tract
what are the motor components of the cerebral cortex?
1) primary motor cortex
2) premotor cortex
3) supplementary motor cortex
the motor components of the cerebral cortex represent ascending hierarchies in motor execution of what type of movements that are associated largely with primary motor cortex activation alone?
simple movements (like a finger)
patterned finger movement are associated with ( )
primary motor and premotor activation
complex movement sequences of fingers are associated with activation of ( )
primary, premotor and supplementary areas, and mental rehearsal alone of such movements
complex movement sequences are associated with ( )
supplementary motor cortex activation
in general, it is through that motor commands often proceed from ( ) to ( ) to ( )
supplementary area to premotor area to primary motor cortex
the primary motor cortex was originally thought to control ( ) as reflected in the homunculus
individual muscles
research findings that there were ( ) where individual muscles could be activated and these corresponded to activation of different groups of muscles led researchers to conclude that the motor cortex maps ( ) rather than ( )
- multiple sites
- movements
- individual muscles alone
further work demonstrated that cells in the motor cortex also had activity related to the direction of ( )
limb movement
cortical motoneurons seem to encode ( ) as opposed to activation of individual muscles
movements and their directions
the activity in the reticular formation favors the ( ) over the ( ) due to the effect of ascending spinoreticular inputs
- excitatory pontine region
- inhibitory medullary region
if a transection was made mor rostrally that spared the red nucleus and rubrospinal pathways, a more mixed picture of ( ) was seen
flexor and extensor tone
mixture of flexor and extensor tone corresponds to the clinical picture of patients with ( ) such as those affecting the cerebral cortices
higher lesions
since the rubrospinal pathway only projects to the cervical cord in humans, ( ) is only seen in the upper extremities wheras ( ) predominates in the lower extremities
- flexor tone
- extensor tone
fine motor contol UMN vs LMN
UMN: markedly diminished; LMN: minimally diminished
pathological reflexes UMN vs LMN
UMN: present; LMB: absent
Babinski: hyper-reflexia and a resultant hypertonia because sensory info entering the cord is under less ( ) and has access to additional motoneurons and motoneuron pools than under normal conditions
descending control
positive phenomena of the UMN syndrome are often referred to clinically as ( )
spasticity
