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physio- exam 1 > Oral Musculature > Flashcards

Oral Musculature Flashcards

1
Q

the genioglossus muscle is very fast, meaning it has a high proportion of ________

A

fast-twitch fibers

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2
Q

what are the “jaw opener” muscles?

A

1) digastric
2) lateral Pterygoid
3) geniohyoid
4) mylohyoid

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3
Q

what muscle contains two heads in a series?

A

digastric

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4
Q

the masseter has 2 parts: deep and superficial. Which part(s) contains mainly slow fibers?

A

both parts

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5
Q

the masseter has a “__________” i.e., slow-fast myosin gradient

A

anterior-to-posterior gradient

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6
Q

bruxing may lead to increased levels of _______, which could lead to what type of contractions?

A

increased levels of slow myosin

could cause slower, less powerful contractions

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7
Q

the temporalis muscle is faster than the masseter, due to it’s relative abundance of __________

A

fast-type myosin

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8
Q

due to the temporalis’s ______________, the site of a lesion/injury could have differing effects

A

compartmentalization

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9
Q

which 3 muscles contain an anterior-to-posterior myosin gradient?

A

Masseter, temporalis, Medial Pterygoid

your “jaw closers”

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10
Q

jaw closing muscles generally have greater amounts of ______ myosin in deep layers and in anterior layers

A

slow

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11
Q

what is Kinesthesia?

A

sense of movement and position

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12
Q

T/F: there is extremely rich sensory information originating from within masticatory muscles, which provide feedback to the CNS

A

true

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13
Q

what are the components of a muscle spindle?

A
  • external capsule
  • muscle fibers
  • efferent nerve fibers
  • sensory fibers (afferents)
  • Lymph
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14
Q

what 2 types of muscle fibers are found in the muscle spindles?

A

1) nuclear bag intrafusal fibers (2-3)

2) nuclear chain intrafusal fibers (4-6)

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15
Q

most fibers in a muscle are “______” fibers which do the work associated with muscle contractions

A

extrafusal

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16
Q

what types of efferent nerves are found in muscle spindles

A

Gamma- fusimotor fibers (most common)

Beta- fusimotor fibers (rare)

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17
Q

which types of sensory fibers are found in muscle spindles? which are “primary” and which are “secondary”?

A

type 1a afferent fibers- primary endings

type 2 afferent fibers- secondary endings

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18
Q

what is the role of gamma motor neurons?

A

maintain high level of spindle sensitivity in shortened muscles

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19
Q

T/F: afferent activity increases as a muscle shortens

A

FALSE- Afferent activity DECREASES

*this is an important component of kinesthesia

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20
Q

what would happen if internal adjustments in the spindle do not occure after the muscle shortens?

A

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

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21
Q

how do gamma motor neurons restore the sensitivity of a shortened muscle?

A

they cause polar regions of INTRAFUSAL fibers to SHORTEN

-stretches the equatorial regions of the spindles

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22
Q

T/F: the distribution of slow-type muscle fibers correlates to the distribution of muscle spindles

A

true

-wheres theres spindles, theres slow-type muscle

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23
Q

where are Golgi tendon organs? where are they found?

A
  • receptors in skeletal muscles
  • located in junction between ends of muscle fibers & the tendon to which they attach

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

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24
Q

the golgi tendon organs will fire most rapidly when a _______ is applied

A

stretching force

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25
Q

what is a EMG? how does it record and analyze muscle activations?

A
  • Electromyography

- records action potentials along sarcolemma of muscle fiber (extrafusal fibers)

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26
Q

T/F: a EMG will reflect the forces generated across a joint

A

false

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27
Q

mandibular movements during mastication are highly _______ and ________, depending on food consistency

A

rhythmic and specialized

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28
Q

which muscles lower/open the jaw during mastication? which ones elevate/close it?

A

openers- digastric and lateral pterygoid

closers- masseter, temporalis, medial pterygoid

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29
Q

list the three masticatory phases:

A

1) preparatory (transport)- tongue, lips, buccinator: highly variable depending on food consistency
2) reduction- food breakdown
3) preswallowing- food bolus formation

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30
Q

T/F: the chewing cycle is highly consistent across divergent species

A

true

31
Q

which masticatory phases are very regular?

A

Reduction and pre swallowing

reduction is both very regular and rhythmic

32
Q

what are the primary sites for control of mastication?

A

brainstem and cerebral cortex

33
Q

what are the sensory nuclei for the central control of mastication?

A

1) Trigeminal sensory nucleus

2) Trigeminal mesencephalic nucleus

34
Q

cells of the trigeminal sensory nucleus innervate what? where do they project?

A

innervate face and oral cavity

project to CEREBELLAR, as well as cerebral cortex

35
Q

what cell bodies are found in the trigeminal mesencephalic nucleus? what sensory reception are they responsible for?

A
  • cell bodies of spindle afferents from jaw CLOSERS

- mechanoreceptors in PDL (perio lig), gingiva and palate

36
Q

what are the motor nuclei for mastication?

A

1) Trigeminal motor nucleus
2) hypoglossal motor nucleus
3) facial motor nucleus

37
Q

what types of motor neurons project from the trigeminal motor nucleus? these have a high degree of ________ organization

A

alpha and gamma motor neurons of jaw muscles

they are topographically organized
facial motor nucleus also shares this characteristic

38
Q

the hypoglossal motor nucleus contains motor neurons that control the _____ muscles

A

tongue

39
Q

masticatory control depends on the interaction between which 3 CNS structures?

A

cerebral cortex

brainstem (where sensory/motor nuclei are found)

cerebellar cortex

40
Q

what is the role of the brain stem in masticatory control?

A
  • can function autonomously

- pattern generator

41
Q

describe the jaw-closing reflex:

A
  • afferent fibers from muscle spindles and cell bodies in mesencephalic nucleus:
  • synapse on ALPHA motor neuron in trigeminal motor nucleus
  • very fast: no modification from higher brain centers needed
42
Q

describe the jaw-opening reflex

A
  • stimulus in oral cavity excites afferents that terminate in spinal trigeminal tract nucleus cells
  • synapse on interneurons, which, in turn, synapse on ALPHA motor neurons in trigeminal motor nucleus
  • motor nucleus innervates jaw openers
43
Q

the jaw-opening reflex is known as “__________” reflex, meaning it is highly modulated for a specific stimulus

A

polysynaptic

44
Q

what is the role of “higher centers” (in the brain) on mastication?

A
  • modulation of mastication
  • can be voluntary, but usually not
  • can modulate the jaw-closing reflex (a little), as well as the jaw-opening reflex
45
Q

what is the role of afferent fibers in mastication?

A
  • modulates mastication depending on food consistency
  • variable receptors involved with several types of input (hard vs soft food, chewy vs crispy)
  • input to brain stem components as well as higher centers
46
Q

T/F: Swallowing is a reflex after its initiated, and is normally unconscious

A

true

47
Q

what are the components of swallowing?

A
  • large area of the brain stem
  • six cranial nerves
  • receptors
  • muscles
48
Q

what occurs during the “preparatory phase” of swallowing?

A
  • bolus is formed and positioned on the back of the tongue
  • tip of tongue presses on maxillary incisors
  • the part of the tongue touching the food rises laterally against buccal teeth
  • the “glossopalatal sphincter” forms (its temporary)
49
Q

what occurs during the INITIAL “oral phase” of swallowing?

A

-lips close, incisors move together
(forms oral seal)

-anterior 2/3rds of tongue moves up against maxillary alveolar ridge
(pushes bolus toward the pharynx)

50
Q

what happens during the later “oral phase” of swallowing?

A

-base of tongue moves down and forward
(opens up chute to pharynx)

-palate moves up
(opens the glossopalatal sphincter)

-palate contacts posterior pharyngeal wall and the side walls of the nasopharynx are opposed
(prevents bolus from entering nasal cavity)

51
Q

what group of muscles is referred to as the “facultative group” during swallowing?

A

muscles involved in preparatory and oral phases of swallowing

  • mandibular (masseter, medial pterygoid, temporalis)
  • facial (labial and buccinator)
52
Q

what is the function of the contraction of the labial and buccinator muscles during swallowing

A

1) contributes to the formation of the oral seal

2) stabilizes the mandible

53
Q

what occurs during the pharyngeal phase?

A

movement of bolus from oropharynx to esophagus

54
Q

muscles involved in the pharyngeal phase of swallowing are collectively referred to as the “__________” of muscles

A

obligate group

vs the “facultative” set with preparatory and oral phases

55
Q

T/F: muscles of the pharyngeal phase are less consistent than preparatory or oral phases

A

false- they are more consistent

56
Q

what occurs during the esophageal phase of swallowing?

A

movement of food along entire esophagus

-takes about 3 seconds

57
Q

__________ waves of contraction move the bolus through the esophagus

A

peristaltic

58
Q

what are the mechanisms that prevent aspiration of food during the pharyngeal phase of swallowing?

A
  • respiration is inhibited
  • larynx and upper esophageal sphincter elevate
  • intrinsic muscles of glottis move vocal cords toward each other
  • bolus moves through sinuses in pharynx
59
Q

which stages of swallowing are voluntary? involuntary?

A

voluntary- preparatory and oral phases

involuntary- pharyngeal and esophageal phases

60
Q

what are the brainstem sensory nuclei that are involved with swallowing?

A
  • Nucleus tractus solitarius (NTS)

- trigeminal sensory nucleus

61
Q

what are the brainstem motor nuclei associated with swallowing?

A
  • Nucleus ambiguous

- facial, trigeminal and hypoglossal nuclei (5, 7 and 9)

62
Q

the _____________ mediates interactions between the sensory and motor nuclei involved in swallowing

A

interneuronal network

63
Q

which interneurons initiate and time/program swallowing?

A

the DORSAL interneurons

64
Q

the ventral interneurons play what role in during swallowing?

A

distribute the excitation to the swallowing motor nuclei

65
Q

where does afferent information during swallowing originate? where does it travel to?

A
  • originates in pharynx, larynx and esophagus
  • info is sent to the NTS
  • results in modulation of swallowing, depending on food consistency
66
Q

T/F: infantile swallow programing of both obligate muscles and facultative muscles both begins in utero

A

False- obligate muscles are programmed in utero

-facultative muscles are markedly different: different patterns of activation before and after tooth eruption

67
Q

T/F: BOTH jaw-opening and jaw-closing muscles have an important role in infant suckling

A

true

68
Q

what is “emesis” also known as? what is its function?

A

emesis= vomiting

function: rid the stomach of its contents (usually natty)

69
Q

what are the different stimuli for vomiting/emesis

A
  • physiological stimuli

- disease-related stimuli

70
Q

what are the phases of vomiting?

A

1) Pre-ejection
2) retching
3) expulsion
4) post-ejection

71
Q

a group of nuclei in the _______ coordinates the act of vomiting

A

medulla

vomiting is under medullary control

72
Q

direct stimulation near the _____ in animals cause vomiting

A

NTS

Nucleus tractus solitarius

73
Q

what are the characteristics of bruxism?

A
  • forceful tooth clenching and grinding during sleep
  • sometimes rhythmic chewing, sometime sustained contractions
  • daytime tooth clenching is very similar to bruxism in terms of mandibular mechanics
74
Q

possible causes of bruxism:

A

A) may have CNS origin- associated with certain sleep phases

B) correlates with stress levels

C) stimulation of hypothalamus can cause stress-like responses and cause excitation of jaw-closer muscles

physio- exam 1 (8 decks)

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