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