EX1; Oral Musculature

Question 1

This muscle is very fast, has a high proportion of fast-twitch fibers; forms the majority of the body of the tongue

Answer 1

genioglossus

Question 2

This muscle is predominantly fast and has two heads in series with functional implications; jaw opener

Answer 2

diagastric

Question 3

This is a protractor muscle accompanying opening; dysfunction of superior head is associated with anterior displacement of TM disc

Answer 3

lateral pterygoid

Question 4

These are strap like muscles involved in jaw opening

Answer 4

geniohyoid

mylohyoid

Question 5

This jaw closing muscle has two parts; deep and superficial and slow fibers predominate on both parts

Answer 5

masseter

Question 6

What are the myosin isoforms of the masseter

Answer 6

adult slow

embryonic, neonatal, alpha cardiac (latter serves in rhythmic contractions

Question 7

What is the gradient (slow-fast myosin gradient) of the masseter

Answer 7

anterior to posterior

Question 8

This may increase in level of slow myosin in which may cause slower, less powerful contractions that could affect chewing, speech, etc.

Answer 8

bruxing

Question 9

This jaw closer contains more fast-type than myosin than masseter; with slow anteriorly and fast posteriorly compartmentalization

Answer 9

temporalis

Question 10

Due to the compartmentalization in the temporalis, what could this mean for an injury/lesion

Answer 10

it may have differential effects

Question 11

This jaw closer has predominately slow myosin and an anterior to posterior gradient

Answer 11

medial pterygoid

Question 12

What is the general pattern involving the relative amount of slow myosin among jaw closers

Answer 12

greater amounts in deep and in anterior
less in superficial and posterior
(slow deep and anterior)
(fast superficial and posterior)

Question 13

This is the sense of movement and position

Answer 13

kinesthesia

Question 14

True or False

Masticatory muscles are under exquisite control

Answer 14

True; protects teeth and soft tissues from damage and ensures effective chewing

Question 15

What does the rich sensory information originating from within the masticatory muscles provide

Answer 15

feedback to the CNS which provides the neural drive for contraction

Question 16

True or False

There is continuously on-going sensory information from all muscles; of which normally not aware of it

Answer 16

True

Question 17

What is the dimensions of a muscle spindle

Answer 17

1-3 mm in length

200µm in diameter

Question 18

What are the two intrafusal fibers that make up muscle fibers

Answer 18

nuclear bad intrafusal fibers (2-3/spindle)

nuclear chain intrafusal fibers (4-6/spindle)

Question 19

Most fibers in a muscle are what, which do the work (force, limb movement) associated with muscle contractions

Answer 19

extrafusal

Question 20

What are the two types of efferent nerve fibers (10 or more/spindle)

Answer 20

gamma; fusimotor fibers (most common)

beta; fusimotor fibers (relatively rare, 1/3 of all spindles)

Question 21

What are the two types of sensory nerve fibers

Answer 21

Ia afferent fibers; primary endings

II afferent fibers; secondary endings

Question 22

True or False

There is lymph in the muscle spindle

Answer 22

True

Question 23

A muscle spindle’s main mode of action is what kind of sensory

Answer 23

a length sensor; apply stretch to spindle; tension

Question 24

This type of motor neuron maintains a high level of spindle sensitivity in shortened muscles

Answer 24

gamma

Question 25

Afferent activity decreases when

Answer 25

as a muscle shortens; an important component of kinesthesia

Question 26

What would happen if the internal adjustments in the spindle do not occur after a muscle shortens

Answer 26

The muscle would function over a range of short lengths where spindles would remain inactive

Question 27

gamma motor neurons cause polar regions of intrafusal fibers to shorten, causing what

Answer 27

stretching equatorial regions restoring sensitivity

Question 28

What is the correlation between the distribution of muscle spindles and of slow type muscle fibers

Answer 28

they mirror that of one another

Question 29

These are receptors in skeletal muscles which are located in the junction between the ends of the muscle fibers and the tendon to which a muscle is attached

Answer 29

golgi tendon bodies

Question 30

Where is the location of golgi tendon bodies

Answer 30

located in the tendon and positioned in-series with muscle fibers

Question 31

What type of signals do the golgi tendon bodies generate

Answer 31

signals that are proportional to the amount of force generated by extrafusal muscle fibers (to the CNS)

Question 32

What information is being picked up by the golgi tendon organs at the upper/middle/lower traces

Answer 32

upper; action potentials of GTO middle; tension in GTO lower; stretch applied to GTO

Question 33

Many of the free nerve endings (those without specialized endings such as pacinian corpuscles) are nociceptive, which means what

Answer 33

they are activated by painful stimuli | others are activated by mechanical stimuli and such can provide information concerning joint position to CNS

Question 34

This is a recording and analysis of muscle activations; action potentials along sarcolemma of muscle fibers (extrafusal)

Answer 34

EMG; electromyography

Question 35

True or False | An EMG is an invasive gathering of information about patterns of muscle activations

Answer 35

False; it is non-invasive

Question 36

EMGs do not necessarily reflect what

Answer 36

forces generated across a joint; solely responds to electrical information

Question 37

What type of patterns can be revealed by an EMG

Answer 37

very interesting ones; like very precise timing of masticatory events relative to each other

Question 38

True or False an EMG can be used clinically to compare someone with normal masticatory functions with someone who has had a mandiblectomy

Answer 38

True

Question 39

This is an extremely complex interaction between motor and sensory components of highly specialized muscles which is highly rhythmic and specific depending upon food consistency

Answer 39

mastication

Question 40

Mastication has rich supplies of afferent information from where

Answer 40

muscles, oral cavity, and facial regions

Question 41

Control and coordination is provided by what

Answer 41

the CNS

Question 42

What two muscles are involved with lowering the mandible (opening)

Answer 42

digastric and lateral pterygoid

Question 43

What three muscles are involved with elevating the mandible (closing

Answer 43

masseter, temporalis, and medial pterygoid

Question 44

This type of animal has a large temporal is and jaw closers express masticatory myosin

Answer 44

carnivores

Question 45

This type of animal has a large masseter; jaw closers express alpha cardiac myosin, no masticatory myosin

Answer 45

herbivores

Question 46

This type of animal has relatively unspecalized mandibular features and a variable diet

Answer 46

omnivores

Question 47

What are the four phases of the chewing cycle

Answer 47

slow opening fast opening fast closing slow closing

Question 48

What are the three masticatory phases

Answer 48

preparatory reduction pre-swallowing

Question 49

This masticatory phase is for transport; tongue, lips, buccinator; highly variable depending on food and consistency

Answer 49

preparory

Question 50

This masticatory phase is food breakdown

Answer 50

reduction

Question 51

This masticatory phase is food bolus formation

Answer 51

pre-swallowing

Question 52

There is little EMG activity during which masticatory stage

Answer 52

preparatory

Question 53

When is the altering EMG activities during mastication

Answer 53

in openers and closers

Question 54

Which phases of mastication are regular?

Answer 54

``` reduction (regular and rhythmic) pre swallowing (regular) ```

Question 55

Each masticatory phase is dependent upon what

Answer 55

food consistency

Question 56

What are the two primary control sites of the brain

Answer 56

brain stem and cerebral cortex

Question 57

What three structures do the brain and cerebral cortex involve in the control of mastication

Answer 57

nuclei afferent tracts of fibers efferent tracts of fibers

Question 58

What are the two sensory nuclei associated with control of mastication

Answer 58

trigeminal sensory | trigeminal mesencephalic

Question 59

This sensory nucleus cells innervate the face and oral cavity; project to cerebellar, as well as cerebral cortex

Answer 59

trigeminal sensory

Question 60

This sensory nucleus cell bodes of spindle afferents from jaw closers, mechanoreceptors in periodontal ligaments, gingiva, and palate

Answer 60

trigeminal mesencephalic

Question 61

What are the three motor nuclei associated with control of mastication

Answer 61

trigeminal motor hypoglossal motor facial motor

Question 62

This motor nucleus contains neurons of the facial muscles; topographically organized

Answer 62

facial motor nucleus

Question 63

This motor nucleus contains motor neurons of tongue muscles

Answer 63

hypoglossal motor nucleus

Question 64

This motor nucleus contains ɑ and Ɣ motor neurons of jaw muscles; high degree of topographic organization

Answer 64

trigeminal motor nucleus

Question 65

This can function autonomously in the control of mastication, no input from higher centers required however normally does receive such input

Answer 65

brain stem

Question 66

What does the brainstem "probably" contain

Answer 66

a pattern generator or neural oscillator for mastication

Question 67

This reflex is monosynaptic; very fast with virtually no modulation from higher centers

Answer 67

jaw closing reflex

Question 68

The cell bodies in the mesencephatic (sensory) nucleus synapses on what

Answer 68

the ɑ motor neurons in trigeminal motor nucleus

Question 69

The jaw closing reflex uses these fibers from muscle spindles

Answer 69

afferent fibers

Question 70

In the jaw opening reflex the stimulus in the oral cavity excites afferents that terminate the spinal trigeminal tract nucleus cells which synapse on interneurons which in turn synapse where

Answer 70

the ɑ motor neurons in trigeminal motor nucleus which innervate jaw openers

Question 71

This is polysynaptic reflex; highly modulated for specific stimulus

Answer 71

jaw opening reflex

Question 72

True or False | Mastication can be entirely voluntary; including that of jaw-closing and jaw-opening reflexes

Answer 72

True; but it is usually not

Question 73

True or False There are variable afferent receptors involved with the several types of input of food consistency; like hard vs soft, chewy vs cripsy

Answer 73

True