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physio- exam 1 > Oral Musculature > Flashcards

Flashcards in Oral Musculature Deck (74):
1

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

fast-twitch fibers

2

what are the "jaw opener" muscles?

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

3

what muscle contains two heads in a series?

digastric

4

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

both parts

5

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

anterior-to-posterior gradient

6

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

increased levels of slow myosin

could cause slower, less powerful contractions

7

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

fast-type myosin

8

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

compartmentalization

9

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

Masseter, temporalis, Medial Pterygoid

(your "jaw closers")

10

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

slow

11

what is Kinesthesia?

sense of movement and position

12

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

true

13

what are the components of a muscle spindle?

-external capsule
-muscle fibers
-efferent nerve fibers
-sensory fibers (afferents)
-Lymph

14

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

1) nuclear bag intrafusal fibers (2-3)

2) nuclear chain intrafusal fibers (4-6)

15

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

extrafusal

16

what types of efferent nerves are found in muscle spindles

Gamma- fusimotor fibers (most common)

Beta- fusimotor fibers (rare)

17

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

type 1a afferent fibers- primary endings

type 2 afferent fibers- secondary endings

18

what is the role of gamma motor neurons?

maintain high level of spindle sensitivity in shortened muscles

19

T/F: afferent activity increases as a muscle shortens

FALSE- Afferent activity DECREASES

*this is an important component of kinesthesia

20

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

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

21

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

they cause polar regions of INTRAFUSAL fibers to SHORTEN

-stretches the equatorial regions of the spindles

22

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

true


-wheres theres spindles, theres slow-type muscle

23

where are Golgi tendon organs? where are they found?

-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

24

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

stretching force

25

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

-Electromyography

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

26

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

false

27

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

rhythmic and specialized

28

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

openers- digastric and lateral pterygoid

closers- masseter, temporalis, medial pterygoid

29

list the three masticatory phases:

1) preparatory (transport)- tongue, lips, buccinator: highly variable depending on food consistency

2) reduction- food breakdown

3) preswallowing- food bolus formation

30

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

true

31

which masticatory phases are very regular?

Reduction and pre swallowing

reduction is both very regular and rhythmic

32

what are the primary sites for control of mastication?

brainstem and cerebral cortex

33

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

1) Trigeminal sensory nucleus

2) Trigeminal mesencephalic nucleus

34

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

innervate face and oral cavity

project to CEREBELLAR, as well as cerebral cortex

35

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

-cell bodies of spindle afferents from jaw CLOSERS

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

36

what are the motor nuclei for mastication?

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

37

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

alpha and gamma motor neurons of jaw muscles

they are topographically organized
(facial motor nucleus also shares this characteristic)

38

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

tongue

39

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

cerebral cortex

brainstem (where sensory/motor nuclei are found)

cerebellar cortex

40

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

-can function autonomously

-pattern generator

41

describe the jaw-closing reflex:

- 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

describe the jaw-opening reflex

-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

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

polysynaptic

44

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

-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

what is the role of afferent fibers in mastication?

-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

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

true

47

what are the components of swallowing?

-large area of the brain stem
-six cranial nerves
-receptors
-muscles

48

what occurs during the "preparatory phase" of swallowing?

-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

what occurs during the INITIAL "oral phase" of swallowing?

-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

what happens during the later "oral phase" of swallowing?

-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

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

muscles involved in preparatory and oral phases of swallowing

-mandibular (masseter, medial pterygoid, temporalis)
-facial (labial and buccinator)

52

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

1) contributes to the formation of the oral seal

2) stabilizes the mandible

53

what occurs during the pharyngeal phase?

movement of bolus from oropharynx to esophagus

54

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

obligate group


(vs the "facultative" set with preparatory and oral phases)

55

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

false- they are more consistent

56

what occurs during the esophageal phase of swallowing?

movement of food along entire esophagus

-takes about 3 seconds

57

__________ waves of contraction move the bolus through the esophagus

peristaltic

58

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

-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

which stages of swallowing are voluntary? involuntary?

voluntary- preparatory and oral phases

involuntary- pharyngeal and esophageal phases

60

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

-Nucleus tractus solitarius (NTS)

-trigeminal sensory nucleus

61

what are the brainstem motor nuclei associated with swallowing?

-Nucleus ambiguous

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

62

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

interneuronal network

63

which interneurons initiate and time/program swallowing?

the DORSAL interneurons

64

the ventral interneurons play what role in during swallowing?

distribute the excitation to the swallowing motor nuclei

65

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

-originates in pharynx, larynx and esophagus

-info is sent to the NTS

-results in modulation of swallowing, depending on food consistency

66

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

False- obligate muscles are programmed in utero

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

67

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

true

68

what is "emesis" also known as? what is its function?

emesis= vomiting

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

69

what are the different stimuli for vomiting/emesis

- physiological stimuli

- disease-related stimuli

70

what are the phases of vomiting?

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

71

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

medulla

(vomiting is under medullary control)

72

direct stimulation near the _____ in animals cause vomiting

NTS

(Nucleus tractus solitarius)

73

what are the characteristics of bruxism?

-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

possible causes of bruxism:

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