Lecture 5- Motor control- LMN Flashcards by Caitlyn Griffin

where does the corticospinal tract end within the spinal cord

mainly in the vental horn and slightly intermediate zone

How well did you know this?

Not at all

Perfectly

where does the rubrospinal tract end within the spinal cord

intermediate zone

How well did you know this?

Not at all

Perfectly

where does the reticulospinal tract end within the spinal cord

ventral horn

How well did you know this?

Not at all

Perfectly

what are the patterns and functions of med vestibulospinal tract in LMN

end in neck/thoracic]
B neck extensors

How well did you know this?

Not at all

Perfectly

what are the patterns and functions of med corticospinal tract in LMN

all spinal levels
B postural flexor m control

How well did you know this?

Not at all

Perfectly

what are the patterns and functions of pontine reticulospinal tract in LMN

all spinal levels
B prox extremity ext

How well did you know this?

Not at all

Perfectly

what are the patterns and functions of lat vestibulospinal tract in LMN

all spinal levels
ipsi prox extremity ext

How well did you know this?

Not at all

Perfectly

what are the patterns and functions of medullary reticulospinal tract in LMN

all spinal levels
b distal extremity flx

How well did you know this?

Not at all

Perfectly

what are the patterns and functions of rubrospinal tract in LMN

end in neck/thoracic
distal UE flexors

How well did you know this?

Not at all

Perfectly

what are the patterns and functions of lat corticospinal tract in LMN

all spinal levels
distal extremity flexor
fine motor control

How well did you know this?

Not at all

Perfectly

what is a type I muscle fiber

slow twitch
high concentration of mitochondria
less glycogen

How well did you know this?

Not at all

Perfectly

what is a type IIa muscle fiber

fast twitch
fatigue resistant
medium concentration of mitochondria and glycogen

How well did you know this?

Not at all

Perfectly

what is type IIb muscle fiber

fast twitch
fatiguable
low concentration of mitochondria
more glycogen

How well did you know this?

Not at all

Perfectly

can muscle fibers transition from one type to another

yes, type II can change to type I

How well did you know this?

Not at all

Perfectly

True/False
All muscles contain all 3 types of muscle fibers with the same ratio

false
all 3 muscle fibers aer present, but they have different ratios

How well did you know this?

Not at all

Perfectly

what happens with a denervated muscle

all LMNs are lost

How well did you know this?

Not at all

Perfectly

what happens when the LMN is loss

polio

How well did you know this?

Not at all

Perfectly

what type of LMN pairs with type I muscle fibers

small LMN
less powerful , last hours
fine motor and postural control

How well did you know this?

Not at all

Perfectly

what type of LMN pairs with type IIa muscle fibers

medium LMN
more powerful, last 1 hour
mixture between I and IIb, gross motor

How well did you know this?

Not at all

Perfectly

what type of LMN pairs with type IIb muscle fibers

large LMN
most powerful, last 1 minute
gross motor and power

How well did you know this?

Not at all

Perfectly

how does motor unit size vary between gross motor and fine motor functions

gross- 1 LMN innervates several hundred/thousand m fibers, large motor unit

Fine= 1 LMN several M fibers, small motor unit

How well did you know this?

Not at all

Perfectly

how are extra-ocular eye muscle considered type 1

they are constantly working aka non- fatiguable

however, can move fast d/t the ratio of LMN per motor unit

How well did you know this?

Not at all

Perfectly

True/False:
There is a 1:1 ratio of LMN to motor unit except with facial expression m

true
they have several LMNs overlap different facial m

How well did you know this?

Not at all

Perfectly

what is intensity encoded by to create LMN activation and force production

AP frequency

How well did you know this?

Not at all

Perfectly

what membrane AP is along the LMN axon terminal

presynaptic

what membrane AP is along the m fibers

postsynaptic

what happens when AP is over 80 Hz

tetanus

what is the difference between temporal and spatial summation

temporal= one presynaptic neuron rapid firing to one postsynaptic spatial= multiple presynaptic firing to one postsynaptic

why are type 1 m fibers activated first

due to small LMN which are higher resistance and need higher voltage

if more force is needed, what muscle fibers are recruited and what regulates these m fibers

type II GTO

what is active insufficiency

the m is so shortened that it decreases m force production

what is passive insufficiency

m is so elongated that it decreases force production

what is the function of nuclear bag cells within the m spindle

static- length (stretch) dynamic- velocity (DTR)

what is the function of nuclear chain cells within the m spindle

only static for length

what doe the alpha motor neurons innervate within the muscle

LMN extrafusal m cells free nerve endings

what doe the gamma motor neurons innervate within the muscle

LMN intrafusal m cells

what doe the primary motor neurons innervate within the muscle

Ia nuclear bag and chain cells both static and dynamic

what doe the secondary motor neurons innervate within the muscle

II static nuclear bag and chain cells

if we have an extrafusal m concentric contraction, what is detected and adjusted

decrease dynamic = decrease Ia activity

if we have an extrafusal m isometric contraction, what is detected and adjusted

increase Ia/II static nuclear bag and chain

if we have an extrafusal m eccentric contraction, what is detected and adjusted

increase in Ia dynamic nuclear bag

what is the function of the m spindle

position sense (static)= Ia/II kinesthesia (dynamic)= Ia

within the cortiobulbar tract, what CN do not have bilateral distribution

CN V/XII normally have contralateral bias

within the cortiobulbar tract, what CN innervates all head m spindle of Ia and II

CN V

a patient shows weakness of inf facial muscles, where is the lesion

UMN lesion

a patient has a UMN lesion resulting in decreased function of bilateral scalp, where is the lesion and what hierarchal level

cingulate motor cortex level 4 dorsal motor nucleus CN VII

a patient has a UMN lesion resulting in decreased function contralateral face, where is the lesion and what hierarchal level

motor cortex and post parietal cortex level IV and III ventral motor nucleus

a patient has a UMN lesion resulting in decreased function of face and scalp, where is the lesion and what hierarchal level

deep brain structure level II

a patient presents with decreased function of the ipsilateral face and scalp, where is the lesion

LMN

what CN are responsible for proprioception of facial m

inter CN V and VII anastomosis

what is the function of the intra CN VII anastomosis

innervate different motor units

what does not happen with a regional injury to intra CN VII anastomosis

does not affect facial expression

what is the importance of the spinal/brainstem reflex

closed loop sensory goes in basic motor function differential diagnosis

what are the two types of spinal/brainstem reflexes

intrasegmental- at same level intersegmental- multiple levels

what are the components of the spinal/brainstem reflex

receptor detects stimuli which is afferent and is sent by interneurons (maybe) to spinal cord for integration then efferent signals are sent to effectors for action

what is the flexor reflex components

noxious stimuli is sent through nociceptice axons (Ad) within intersegmental reflex in spinal cord (Lissauers tract) and efferent signals excite flexors and inhibit extensors to remove injured body part away from noxious stimuli

where is flexor reflex most common

more common in UE but if in LE crossed extension reflex is also there

what is the crossed extension reflex

noxious stimuli is sent through nociceptive axons. interneurons have alternating excitatory and inhibitory signals. which excite ipsi flexors and contra extensors while inhibiting ipsi ext and contra flx. Thus the affected limb withdrawals and contra is there to maintain balance

what is the DTR signals sent for patellar tendon reflex

afferent dynamic (Ia) signals of quad sent to spinal cord for alpha motor neurons to excite quads through intrasegmental and inhibit HS through interneuron intersegmental reflex. resulting in knee jerk reaction

what is the importance of GTO reflex

fine adjustments of force production initiate additional forms of autogenic inhibition at higher tension levels- clasp knife effects

how can reflexes be modulated by UMN

Ia signals to spinal cord then moves through various segments (spinal reflex) then to higher levels (either conscious or unconscious) which then can override why we have to distract pt during DTR

if spinal/brainstem reflex are considered closed loop, what is the difference between CPG open loop

spinal reflex needs sensory input aka closed loop CPG does not. It is a pre written motor program that does not need sensory info

what are the voluntary locomotor regions

cont of reticular formation system diencephalic and mesencephalic

what is the function of DLR and MLR and what regulates these regions

to coordinate CPG that are regulated through the hierarchical control systems