341 Exam 3 - Motor System Pt 1

motor unit

a single lower motor neuron (LMN) and all the muscle fibers it innervates as it branches

LMN

Are cranial nerves upper motor neurons (UMN) or lower motor neurons (LMN)?

False

True or false: upper motor neuron (UMN) cell bodies are only found in the cerebral cortex.

True

True or false: upper motor neuron (UMN) cell bodies can be found in the cerebral cortex or the brainstem.

anterior horn

Are cell bodies of lower motor neurons of the spinal cord found in the anterior horn or the posterior horn? 

medially, laterally

In the anterior horn of the spinal cord, lower motor neurons (LMN) for axial muscles are located more ____ (medially or laterally) and distal muscles are located more ____ (medially or laterally)

posterior, anterior

In the anterior horn of the spinal cord, lower motor neurons (LMN) for flexors are more ____ (anterior or posterior) and extensors are more ____ (anterior or posterior).

fewer, more

Smaller motor unit → ____ (more or fewer) muscle fibers innervated → ____ (more or less) fine motor control.

more, less

Larger motor unit → ____ (more or fewer) muscle fibers innervated → ____ (more or less) fine motor control.

true

True or false: the more quickly in succession action potentials occur in lower motor neurons (LMN), the more action potentials and twitches in the muscle fiber, and the stronger the force of the muscle contraction.

temporal summation

The more quickly in succession action potentials occur in lower motor neurons (LMN), the more action potentials and twitches in the muscle fiber, and the stronger the force of the muscle contraction.

Does this description show how spatial summation or temporal summation is related to the force production of muscle contraction?

3

How many different types of muscle fibers do we have?

false

True or false: muscles contain all three types of muscle fibers (type I, type IIa, type IIb) in the same proportion.

true

True or false: most muscles contain all three types of muscle fibers (type I, type IIa, type IIb) in varying proportions depending on the muscle’s primary function. 

type I, type IIa, type IIb

Name the three types of muscle fibers.

type I

type of red muscle fiber involved in a slow-twitch (S) motor unit that allows muscle to contract weakly for long periods of time (e.g., standing)

type IIa

type of white muscle fiber involved in a fast-twitch, fatigue-resistant (FR) motor unit that allows muscle to contract more strongly for a moderate amount of time (e.g., running)

type IIb

type of white muscle fiber involved in a fast-twitch, fatiguable (FF) motor unit that allows muscle to contract very strongly for a brief amount of time (e.g., jumping) 

type I

Name the red muscle fiber.

type IIa, type IIb

Name the 2 white muscle fibers.

slow-twitch (S)

Name the motor unit associated with type I (red) muscle fibers.

fast-twitch, fatigue-resistant (FR)

Name the motor unit associated with type IIa (white) muscle fibers.

fast-twitch, fatiguable (FF)

Name the motor unit associated with type IIb (white) muscle fibers.

type I, slow-twitch (S)

Name the muscle fiber and motor unit that allow muscles to contract weakly for long periods of time (e.g., standing).

type IIa, fast-twitch, fatigue-resistant (FR)

Name the muscle fiber and motor unit that allow muscles to contract more strongly for a moderate amount of time (e.g., running)

type IIb, fast-twitch fatiguable (FF)

Name the muscle fiber and motor unit that allow muscles to contract very strongly for a brief amount of time (e.g., jumping).

true

True or false: all the muscle fibers in a motor unit are of a single type.

slow-twitch (S)

Which type of motor unit involves lower motor neurons (LMN) of the smallest size?

fast-twitch, fatigue-resistant (FR)

Which type of motor unit involves lower motor neurons (LMN) of intermediate size?

fast-twitch, fatiguable (FF)

Which type of motor unit involves lower motor neurons (LMN) of the largest size?

size principle

principle that states that motor neurons reach threshold in order of increasing size, such that slow-twitch (S) motor units are recruited for muscle contraction first, followed by fast-twitch, fatigue-resistant (FR) motor units and fast-twitch, fatiguable (FF) motor units

motor control

the ability to regulate or direct the mechanisms essential to movement; involves planning, organizing, initiating, executing, grading, coordinating, and learning

planning, organizing, initiating, executing, grading, coordinating, learning

Name the 7 steps involved in motor control.

built-in patterns, descending pathways, higher centers

Name the 3 overlapping classes from which lower motor neurons (LMN) receive input.

central pattern generators

interneurons involved in motor programs for rhythmic, autonomic movements such as walking and breathing

central pattern generator

Which type of built-in pattern is more complex: reflex or central pattern generator

reflexes, central pattern generators

Name 2 types of built-in patterns that lower motor neurons (LMN) receive input from.

hierarchical, parallel

Name the two broad ways that the components of motor control (built-in patterns, descending pathways, higher centers) are organized.

corticospinal tract 

The “pyramidal tract” refers to which descending pathway? 

cerebral peduncles, basal pons, pyramids

Name the 3 three appended structures of the anterior brainstem that upper motor neuron (UMN) fibers of the corticospinal tract (CST) travel through.

midbrain

Which part of the brainstem are the cerebral peduncles (crus cerebri) located? (midbrain, pons, medulla)

pons

Which part of the brainstem is the basal pons located? (midbrain, pons, medulla)

medulla

Which part of the brainstem are the pyramids located? (midbrain, pons, medulla)

primary motor cortex

area of cortex involved in the corticospinal tract (CST) that initiates voluntary movement and is the location of the motor homunculus

supplementary motor cortex, premotor cortex

areas of cortex involved in the corticospinal tract (CST) that are responsible for motor planning (praxis) and postural adjustments

praxis

the ability to plan, sequence, and execute coordinated movements

primary somatosensory cortex

area of cortex involved in the corticospinal tract (CST) that receives and processes sensory feedback for motor control 

motor association cortex

area of cortex involved in the corticospinal tract (CST) that is involved in the cognitive planning of movement; has input to other motor cortices

primary motor cortex, supplementary motor cortex, premotor cortex, primary somatosensory cortex, motor association cortex 

Name the 5 cortices involved in the corticospinal tract (CST).

primary motor cortex

On which cortex is the motor homunculus located?

motor homunculus

topographical map that depicts each body part’s cortical representation for voluntary movement; located on the primary motor cortex (precentral gyrus)

face, mouth, hands

Name the 3 body parts that have the largest cortical representation on the motor homunculus.

face, mouth, hands 

The ____, ____, and ____ have the largest cortical representation on the motor homunculus for speech, eating, and fine motor control. 

false

True or false: the organization of the motor homunculus is fixed at birth.

true

True or false: the organization of the motor homunculus is not permanent and boundaries are not exact; cortical representation is dependent on neuro-occupation and neuroplasticity.

medial

When considering the motor homunculus, which side of the primary motor cortex (precentral gyrus) are the lower extremities represented on? (lateral or medial)

true

True or false: body parts can lose cortical representation on the motor homunculus through inactivity. 

true

True or false: persons with amputations will lose cortical representation of the amputated limb on the motor homunculus, and the motor homunculus will reorganize to optimize cortical representation of body parts.

CN III (oculomotor), CN IV (trochlear), CN VI (abducens)

Which three cranial nerves control movements of the eyeball?

CN VII (facial) 

Which cranial nerve innervates muscles of facial expression?

CN XII (hypoglossal) 

Which cranial nerve is most associated with tongue movements? 

corticobulbar tract

What is the name of the descending pathway that primarily controls voluntary movement of the head and neck.

lateral

When considering the motor homunculus, which side of the primary motor cortex (precentral gyrus) does the corticobulbar tract originate from? (lateral or medial)

somatic motor, branchiomeric 

Corticobulbar tract neurons are the upper motor neurons for ____ ____ and ____ cranial nerves. 

CN III (oculomotor), CN IV (trochlear), CN VI (abducens)

Which somatic motor cranial nerves (3) innervate the extraocular muscles?

CN V (trigeminal)

Which branchiomeric cranial nerve innervates muscles of mastication

CN VII (facial)

Which branchiomeric cranial nerve innervates muscles of facial expression?

CN IX (glossopharyngeal) 

Which branchiomeric cranial nerve innervates muscles of swallowing? 

CN X (vagus)

Which branchiomeric cranial nerve innervates muscles of swallowing and speaking? 

CN XI (accessory)

Which somatic motor cranial nerve innervates the sternocleidomastoid and upper trapezius?

CN XII (hypoglossal)

Which somatic motor cranial nerve innervates muscles of the tongue

bilateral

Somatic motor and branchiomeric cranial nerve nuclei typically receive ____ (bilateral or contralateral) corticobulbar innervation.

CN VII (facial)

Which cranial nerve is the exception to typical bilateral corticobulbar innervation of somatic motor and branchiomeric cranial nerves?

bilaterally

Corticobulbar neurons ____ (bilaterally or contralaterally) innervate CN VII (facial) for upper facial muscles.

contralaterally

Corticobulbar neurons ____ (bilaterally or contralaterally) innervate CN VII (facial) for lower facial muscles.

bilateral

Do upper facial muscles receive bilateral or contralateral innervation from corticobulbar neurons?

contralateral

Do lower facial muscles receive bilateral or contralateral innervation from corticobulbar neurons?

lower 

A right hemispheric stroke would lead to left hemiparesis of the ____ (upper or lower) face. 

LMN

Is Bell’s palsy an upper motor neuron (UMN) or lower motor neuron (LMN) condition?

upper motor neuron syndrome

clinical condition produced by damage (usually vascular) to any part of the upper motor neuron (UMN); characterized by

• initial flaccid paralysis (hypotonia + weakness)

• evolution to spasticity (hypertonia + hyperreflexia)

• abnormal reflexes in general

• may have clonus 

may be called spastic hemiplegia or spastic hemiparesis

upper motor neuron syndrome

What is another term for spastic hemiplegia or spastic hemiparesis?

hypertonia

increased muscle tone

hypotonia

decreased muscle tone

hyperreflexia

increased reflexes

hypertonia, hyperreflexia

Name the 2 characteristics of spasticity in upper motor neuron syndrome.

hyperreflexia, hypertonia

In upper motor neuron syndrome, ____ leads to ____. 

velocity

Hyperreflexia and hypertonicity are ____ dependent.

slow, less

When considering hyperreflexia, ____ stretch meets ____ resistance.

clasp-knife effect

characteristic of spasticity in which hypertonia “melts'“ away during slow stretch

slow

If a patient has hyperreflexia and hypertonia, would you want to do a slow stretch or a quick stretch to improve range of motion? 

flexors, extensors

In upper motor neuron syndrome, spasticity is most pronounces in upper extremity ____ and lower extremity ____.

true

True or false: In upper motor neuron syndrome, spasticity is most pronounced in upper extremity flexors and lower extremity extensors.

false

True or false: In upper motor neuron syndrome, spasticity is most pronounced in upper extremity extensors and lower extremity flexors.

clonus

rapid series of rhythmic contractions maintained during duratoin of sudden stretch; commonly seen in upper motor neuron syndrome along with hypertonia and hyperreflexia 

proximal

In upper motor neuron syndrome, does proximal or distal voluntary movement typically return first?

gross motor

In upper motor neuron syndrome, does gross motor or fine motor voluntary movement typically return first?

true

True or false: in upper motor neuron syndrome, return of voluntary movement typically occurs proximal to distal and gross motor to fine motor.

false 

True or false: in upper motor neuron syndrome, return of voluntary movement typically occurs distal to proximal and fine motor to gross motor.

UMN

Does the following describe an UMN or LMN lesion?

• decreased strength

• increased muscle tone

• increased stretch reflexes

• mild atropy

• clonus

• pathological reflexes

LMN

Does the following describe an UMN or LMN lesion?

• decreased strength

• decreased muscle tone

• decreased stretch reflexes

• severe atropy

• fasciculations

• fibrillations