Module 3
The vestibulocollic component acts on and its goal is?
Acts on neck muscles to keep head level
What does the otolith receptors register?
Linear acceleration and static tilt of head
A lesion in the corticospinal tract would cause what
Loss of fine control of digits
What structure mediates speed, timing, strength and coordination of limb movement
MLR
Define feedback posture adjustments
Posture adjustments based upon external forces
Is the VOR otolith or semi-circular canals?
Semi-circular canals
Is the kinocillium associated with semicircular canals or otolith receptors
Semicircular canals
What are the two types fo vestibular receptors?
Semicircular canals, otolith receptors
What modulates the VOR when retinal slip occurs
The cerebellum
T or F: Although the corticospinal pathways function like the brainstem pathways they allow for further fractioning like independent finger movements
True
T or F: Basal ganglia and cerebellum provide connections between hierarchical levels
True
T or F: Central pattern generators can function without descending input or peripheral input
True
T or F: Cervicospinal and cervicocolic reflexes really just make use of the stretch reflex
True
T or F: Corticospinal tracts descend through pons and medulla to spinal cord
True
T or F: Descending signals from the CNS can mediate locomotor pattern
True
T or F: Frontal eye field is primarily concerned with voluntary eye movements
True
T or F: Neural control of eye movements have 3 levels
True
T or F: Postural responses are triggered by somatosensory, visual, and vestibular input
True
T or F: Vestibular hair cells transduce mechanical stimuli into neural signals
True
Physical tiltin of an animals head down causes legs to be flexed or extended
Extended
Dorsiflection leads to leg extension or flexion
Extension
Ventral motor neurons are extensors or flexors?
Extensors
Where do gaze centers send input to?
Eye muscles
Function of vestibuloocular reflex (VOR)
Fixing eyes in place while head moves
Dorsal motor neurons are extensors or flexors?
Flexors
What is the highest level of ocular control?
Frontal eye field
What structure(s) is responsible for producing conjugated eye movements
Gaze centers
What is the lowest level of ocular control
Gaze centers and cranial nerve nuclei
What eye muscle rotates eyes up and towards temple
Inferior oblique
What eye muscles does cranial nerve III innervate?
Inferior rectus, superior rectus, medial rectus, inferior oblique
Dorsiflection of the neck lifts the neck up or pulls it down?
Lifts it up
Where do the corticospinal tracts originate?
motor cortex
How are the semicircular canal arranged
3 different planes perpendicular to each other so 360 degree movement can be measured
Give an example of a stepping reaction
A unexpected push from behind would cause a person to step in front of them
The cervicospinal component acts on and its goal is?
Acts on limb muscles to be synergistic or antagonistic with vestibulospinal reflexes
The vestibulospinal component acts on and its goal is?
Acts on limb muscles to prepare body for falling
The cervicocollic component acts on and its goal is?
Acts on neck muscles (as a stretch reflex) to by synergistic with vestibulocollic reflexes
Benefit of three motor systems being organized in series?
Allows the lower levels like the spinal cord to create complex movements with very litter innervation from higher regions
What do the semicircular canals register?
Angular acceleration
Define protective reactions
Arms thrown out, trunk rotated to break fall
When do anticipatory postural adjustments occur
At the same time or prior to voluntary movement
What does the medial group of the brainstem innervate?
Axial muscles of neck and back
What two spots do descending motor pathways originate from
Brainstem nuclei, and cerebral (motor) cortex
What are the three mechanisms for spatial coordination based on divergence (movement)?
Branching of descending fiber, branching by interneuron, imported synergy
Gaze centers involve what two parts
Center for vertical gaze (riMLF) and centers for horizontal gaze (PPRF)
What are the two types of neck reflexes
Cervicocollic component, cervicospinal component
Generally what is the function of frontal eye field?
Command lower level ocular structures
Define temporal coordination (movement)
Commands to each muscle must have appropriate amplitude and duration
What are the two controls of posture
Compensatory (feedback), and anticipatory (feedforward)
Is the spinothalamic column contralateral or ipsilateral
Contralateral
Function of midbrain locomotor region
Controls the timing and strength of muscle contraction
What do the lateral corticospinal spinal cords descend and where do they terminate
Descend the dorsolateral spinal cord and they terminate in the dorsal lateral part of the ventral horn
What do the ventral corticospinal spinal cords descend and where do they terminate
Descend the ventral spinal cord and they terminate in the ventromedial part of the ventral horn
How do we switch between gaits?
Descending motor pathways
Is ankle strategy distal to proximal or proximal to distal
Distal to proximal
T or F: Hair cells are of the same size
False
T or F: The frontal eye field can only influence eye movements indirectly through the superior coliculus
False; both directly or indirectly
T or F: Motornueronal pools are NOT organized somatotopically in the ventral horn.
False; they are. Medial ventral horn control more proximal muscle whereas ventral controls more lateral muscles
T or F: Appropriate anticipatory responses to postural disturbances can NOT be learned
False; they can
Which type of postural adjustment is reflex-like?
Feedback
Define rescue reactions
Gross movemnts of the whole body that occur to restore balance once the center of mass is outside the base of support
Center pattern generators are composed by what organization
Half-center model
Generally explain how semicircular canals work
Head movement causes fluid to move through the canals causing hair cells to bend and depolarize.
Does ankle or hip strategy move COM faster?
Hip
Are the ventral/lateral cervical spinal cord and the medial/lateral brainstem contralateral or ipsilateral
Ipsilateral
Is the dorsal column medial lemniscus ipsilateral or contralateral
Ipsilateral
Define kinocilium
Largest hair cell
What eye muscles does cranial nerve VI innervate?
Lateral rectus
Function of ankle strategy
Maintains trunk vertical while moving the center of mass
What eye muscles rotate eyes toward nose and temple respectively?
Medial and lateral rectus
What controls whole-body movements?
Medial system
What are the two descending brainstem pathways
Medial system, lateral system
What are the receptors for the neck reflex?
Muscle spindles and joint receptors
Define spatial coordination (movement)
Motor commands must be distributed to appropriate combinations of muscles
The frontal eye field is analogous to what for muscles?
Motor cortex
lateral corticospinal tract control what movements
Movements of limbs
Ventral corticospinal tract control what movements
Movements of the trunk and neck
Define smooth pursuit
Moving eyes smoothly while keeping head still
What two structures does the vestibular nuclei connect to?
Nuclei of the extraocular muscles, and the vestibulospinal tract
Generally what is the function of the superior colliculus
Orient eyes and head towards stimulus
Origin and function of reticulospinal tract
Originate in pontine and medullary reticular formation. maintenance of posture
Origin and function of rubrospinal tract
Originates in magnocellular red nuclei, controls hand and finger movements during reach
Origin and function of tectospinal tract
Originates in superior colliculus. Coordinates head and eye movements.
Origin and function of vestibulospinal tract
Originates in vestibular nuclei. Reflex control of balance and posture
Are the vestibular reflexes otolith or semi-circular canals
Otolith
VEstibular reflexes are evoked by otholith or semicircular canals
Otolith
What are the receptors for vestibular reflexes?
Otolith organs
What is the center for horizontal gaze?
PPRF
What somatosensations does the spinothalamic column carry?
Pain, temp, affective touch
Define movement field
Part of the visual field to which the eyes move in response to stimulation of a given region of superior colliculus
define feedforward postural adjustments
Predict disturbances and produce preprogrammed response that maintain stability
Generally was is the function of lower level ocular control
Produce eye movement
What somatosensations does the dorsal column medial lemniscus carry?
Proprioception, discriminative touch
What does the lateral group of the brainstem, innervate?
Proximal and distal muscles (proximal by medial lateral group and distal by lateral lateral group)
Is hip strategy distal to proximal or proximal to distal?
Proximal to distal
Stimulation of the MLR is mediated by what tract?
Reticulospinal tract
Half-center model controls what type of activity
Rhythmic alternating activity
What are the tracts in the lateral brainstem
Rubrospinal tract
Define saccades
Small but fast eye movements that direct gaze to desired target
Give an example of a sweeping example
Someone reaching out to stabilize themselves while falling
Motor movements require which two aspects
Spatial and temporal coordination
Where is circuitry for generating the basic locomotor rhythm (CPG) located?
Spinal cord
What are the three types of rescue reactions?
Stepping, sweeping, protective reactions
Define stumbling correcting response
Stimulation of a dorsal paw during swing phase triggers enhanced flexion moving paw "up and over"
Define reflex reversal
Stimulus applied to dorsal foot during stance causes increased extension of the limb
What eye muscles rotate eyes upward and downward respectively?
Superior and inferior rectus
What is the middle level of ocular control
Superior colliculus
What does the frontal eye field command?
Superior colliculus and gaze centers
What eye muscle rotates eyes toward nose and down
Superior oblique
What eye muscles does cranial nerve IV innervate?
Superior oblique
What functions does postural control serve? (3)
Support body against gravity, stabilize supporting parts of body while other parts are moved, balance body on base of support
Function of sensory input from peripheral receptors
Switching to locomotor pattern from stance to swing and vice versa. Adapt the locomotor pattern to changes in the external environment
Define vergence
The ability to converge and diverge eye contact
Generally how to otolith receptors work
The otoconia move due to gravity causing underlying hair cells to depolarize
Define bilateral pyramidotomy
Transection of the corticospinal tracts
T or F: Vestibular structures in both the left and right ear work together
True
T or F: anticipatory postural adjustment is incorporated into the motor plan for voluntary movement
True
T or F: reciprocal inhibition happens in the same eye
True
Does utricle or saccule detect tilt of head?
Utricle
What are the two types of otolith receptors and their respective direction
Utricle (horizontal), saccule (verticle)
What descending pathway is associated with maintenance of posture, integration of body-limb movements and with directing the course of locomotion
VEntromedial
Do ventral CST or lateral CST and medial or lateral brainstem have a transient impact when spinal lesions occur?
Ventral CST, and medial brainstem
What are the two corticospinal tracts
Ventral corticospinal tract, lateral corticospinal tract
What is the three nuclei path in the VOR?
Vestibular nuclei -> extraocular nuclei -> extraocular muscles
What is the difference between vestibular reflexes and the neck reflexes
Vestibular reflexes solely determine posture by position of the head. Neck reflexes rely on position of neck adn head (stretching of the neck)
What are the two types of postural reflexes?
Vestibular reflexes, neck reflexes
What are the two types of vestibular reflexes
Vestibulocollic component, vestibulospinal component
What are the three tracts of the medial brainstem?
Vestibulospinal tract, reticulospinal tract, tectospinal tract
What sensory systems work together to help control posture
Visual, vestibular, somatosensory
Define the swing phase
When you stretch your leg out during an step
Define stance phase
When your leg is planted into the ground
Give an example of isolated cord preparation
You can walk on a treadmill even though your spinal cord is severed
Define corticospinal tract:
fibers that originate in the (pre)motor cortex and synapse directly on the spinal cord
Define posture
position of body in space
What is the center for vertical gaze?
riMLF
