oral physiology Flashcards
changes in contractile properties leads to
Altered power output, fatigability
can contractile protein isoform changes occure
yes under some conditions
why are fiber types compartmentalized in oral musculature
specific tasks served by different sets of muscle fibers
- good control of mandible
what fibers are found in the genioglossus
Very fast, high fast-twitch fibers
what kind of muscle is genioglossus
extrinsic tongue muscle
what forms a majority of the body of the tongue
Genioglossus
speed of digastric
Mainly fast
does the Digastric have to work synchronously
No, allowing adjustment of forces from one head
what muscles have 2 heads
Digatric
Hyoideus
action of the lateral pteryoid
Protractor (accompanies opening)
what are the jaw openers
Lateral pterygoid
Digastric
geniohyoid
Mylohyoid
dysfuction of the superior head ot the lateral pteryoid leads to
anterior displacement of the TM disc in TMJ dysfunction
parts of the masseter muscle
deep
superficial
what fibers predominate in the masseter muscle
slow fibers predominate in both parts of the masseter
what myosin isoforms are found in the masseter
Adult slow (predominant)
embyronic
neonatal
alpha cardiac
roll of alpha cardiac fibers in the masseter
rhythmic contractions
what is the myosin gradient in the masseter muscle
Antierior: slow
Posterior(near joint): fast
cause of bruxing
Hypertrophy in the masseter
what causes hypertrophy in limb muscle
Upregulation of slow myosin
bruxism affect on muscle
Increase in level of slow myosin
- less powerful contraction which could affect shewing and speech
speed of temporalis
faster than masseter(more fast type myosin than masseter
Compartmentalization of temporalis
Slower fibers anterior
faster fibers posterior
EMG studies of the temporalis shows
mean power frequency higher in females and decreases with aging
compartmentalization of temporalis means that lesions/injury could lead to
differential effects
fiber orientation of the temporalis
anterior: verticle
Posterior: horizontal
superficial vs deep temporalis fiber types
Superficial: faster
Deep: slower
what myosin is found in the medial pterygoid
SLow myosin
medial pteryoid gradient anterior and poster
Anterior: slow
Posterior: fast
general pattern for all jaw closes in speed of myosin
Anterior: slower
Posterior: fast
Superficial: fast
Deep: slow
Kinesthesia
Sense of movement and position
why are masticatory muscles are under exiquiste control
Protects teeth and soft tissues from damge and ensures effective chewing
Roll of the rich sensory info from within the masticatory muscles
provide feedback to CNS to provide neural drvie fro contraction
are we aware of kinesthesia
Not aware of it and continuously on goind
why is kinesthesia important
drive very different motor functions to control precise forces
parts of muscle spindles
Polar region
Equatorial Region
Polar region
size of muscle spindles
1-3 mm in length
200 micrometers in diamter
what determines the limit of a muscle spindle
External capsule
parts of the muscle spindle
External capsule Muscle fibers Efferent nerve fibers Sensory nerve fibers Lymph
what type of muscle fibers are found in the muscle spindle
nuclear bag intrafusal fibers(2-3 per spindle)
Nuclear chain intrafusal fibers (4-6 per spindle)
roll of most of the fibers in a muscle are what
Extrafusal doing the work and muscle contractions
where are nuclear bag intrafusal fibers
at the swelling in the equitorial region of the spindal
where are nuclear chain intrafusal fibers found
along the length of the equitorial region of the spindal
how is the polar region of the muscle spindle constructed
Striated
what efferent nerve fibers are foudn in the muscle spindle
Gamma fusimotor fibers (Most common)
Beta fusimotor fibers (rare, 1/3 of all spindles)
what sensory nerve fibers are found in the muscle spindle
1a afferent fibers
II afferent fibers
what are Ia afferent fibers
Primary endings
what are II afferent fibers
Secondary endings
where are Ia afferent fibers found
wrap around the equitorial region
wheree are II afferent fibers found
wrap around the jucntion of the equitorial and polar region
what do muscle spindles sense
Sense length not tension and report that to CNS
Roll of gamma motor neurons in muscle spindles
Maintain a high level of spindle sensitivity in shortened muscles
what happens to the afferent activity of the muscle spindle as the muscle shortens
Afferent activity decreases
What is the decreasing of afferent activity as muscle shortens important
an important component of kinesthesia
what would happen if internal adjustments in the spindle would not occur after a muscle shortens
the muscle would function over a range of short lengths where spindles would remain inactivity
action of gamma motor neurons for muscle spindle sensitivitty
cause polar region of intrafusal fibers to shorten, ultimately stretching the equatorial regions and restoring the spindles sensitivity
does the lack of an AP matter for a muscle spindle when reporting to the CNS
Yes, just as important as an AP
what kind of fibers do muscle spindles tend to associate with
with posterior/slow muscle fibers
where are golgi tendon organs found
in junction between ends of muscle fibers and tenden *in the tendon and in series with muscle fibers)
what do golgi tendon organs do
Generate signals that are proportional to amount of force generated by extrafusal muscle fibers
how do golgi tendon organs fire
in relation to the force generated(more firing for more force)
presence of free nerve endings in joints
lots of free nerve endings in joints
what do free nerve endings (without specialized endings sense):
Nociceptive(activated by pain)
also mechanical stimuli(provide info for joint position)
- to the CNS
what does an EMG do
recording and analysis of muscle activators
an EMG works by sensing
action potion along sarcolemma of muscle fibers
does EMG reflect forces generated across a joint
Not necessarily(antagonistic muscles generating equal forces)
what did the EMG show about mastication
very precise timing of masticatory events relative to each other
what components interact during mastication
Motor and sensory
how specialized is the muscles of mastication
Highly specialized
what afferent info comes from mastication
From muscles, oral cavity, and facial regions
what control and coordinates mastication
The CNS
how does the mandible move during mastication
Highly rhythmic and specific depending on food consistancy
what muscles does lowering of the jaw
Digastric and lateral pterygoid
what muscles do elevation
masseter
temporalis
medial pterygoid
what mastication muscle is found to be large in carnivors
large temporlis
what mastication muscle found to be large in herivors
large masseter
myosin differences in carnivors and herbivors
carnivores: express masticatory myosin
Herbivores: express alpha cardiac myosin and no masticatory myosin
specialization of muscles in omnivores
relatively unspecialized due to varied diet
how do squirels open nuts if they lack masticatory mucosa
single hole in the nut
how do squirrels open nuts if they have masticatory mucosa
obliterated shells
what are the 4 phases of the chewing cycle
slow opening
fast opening
fast closing
slow closing
what are the masticatory phases
Prepartory
Reduction
pre-swallowing
why does chewing slow near the teeth
to protect the teeth
what happens in the preparatory phase of mastication
tranport
what is involved in the preparatory phase of mastication
tongue
lips
buccinatory
(highly variable depending on food consistency)
what happens in the reduction phase of mastication
food breakdown
what happens in the pre-swallowing phase of mastication
food bolus formation
EMG activtiy in jaw closers during prep phase
Little EMG activity
EMG activity in openers and closers in all phases
Alternating EMG activitiyopeners and closers in all phases
EMG activity during prep phase
fairly variable
EMG activity during reduction phase
REgular and rhythmic
EMG activity in preswallowing phase
Regular
speicific characterisits are depending on what for EMG actiivty during mastication
Dependent on food consistency
the primary site of control of mastication
brain stem and cerebral cortex
what is found in the brainstem and cerebral cortex for control and communication of mastication
Nuclei
Afferent (sensory) tracts
Efferent (motor) tracts
what sensory nuclei are used for mastication
Trigeminal sensory nucleus
Trigeminal mesencephalic nucleus
what does the trigeminal sensory nucleus innervate
Face and oral cavity
what does the trigeminal sensory nucleus project to
Cerebellar and cerebral cortex
what does the trigeminal mesencephalic nucleus sense
Spindles afferents from jaw closers
mechanoreceptors in periodontal ligaments, gingiva, and palate
MOtor nuclei for mastication
Trigmeinal motor nucleus
Hypoglossal motor nucleu
Facial motor nucleus
what does the trigeminal motor nucleus project as for mastication
Alpha and gammma motor neurons of jaw muscles
orginization of the trigeminal motor nucleus
High degree of topographic organization
what does the hypoglossal motor nucleus project out to as
Motor nuerons of tongue muscles
what does the facial motor nucleus do
it is the motor nueons of facial muscles
how is the facial motor nucleus organized
topographically
does the brain stem need anything else to control mastication
No, can function autonomously in the control of mastication (but this is not normal)
what does the brain stem do for mastication
Contains a pattern generator (neural oscillator) for mastication
path of the jaw closing reflex
- Afferent fibers from Muscle spindles have cell bodies in the mesencephalic (sensory) nucleus)
- Mesencaphalic snsory nucleus sends its axon to synpase on Alpha motor neurons in trigeminal motor ncuelus
- trigeminal motor nucleus sends out axons to induce closing
synapses in the jaw closing reflex
Monosynaptic
characteristics of monosynaptic reflexes
very fast with basically no modulation from higher centers
steps of the jaw-opening reflex
- stimulus in oral cavity excites afferents(cell bodies in trigeminal gnaglion) that terminate in speinal trigeminal tract nucleus to synapse with interneurons
- interneurons synpase on alpha motor neurons in trigeminal motor nucleus
- trigeminal motor nucleus innervates jaw openers
number of synapses in the reflex of jaw opening
polysynpatic reflex
characteristics of polysynaptic reflexes
highly modulated for specific stimulus
roll of higher centeres in mastication
Modulation of mastication and voluntary (jaw opening somtimes and jaw opening)
Roll of afferents in mastication
Modulation of mastication depending on specific food consistency
what do afferents sense in mastication
Variale receptors invovled with several types of input
what do afferents input to
to the brain stem components and higher centers
when does swallowing occur
Reflex after initiation(can be voluntary); normally unconscious
how common is swallow
about 1000 per day (1 per minute except sleep or eating
how complex is swallowing
very complex
Components of swallowing
Large area of brain stem
6 cranial nerves
receptors
muscles
4 phases of the movement of food bolus
Preparatory phase
Oral phase
Pharyngeal phase
Esophageal phase
what happens to food during the preparatory phase
bolus formation
what is the preparatory phase the same as
Pre-swallowing phase at the end of mastication
what is formed during the preparatory phase
Bolus is formed
glossopalatal sphincter
where is the Bolus positioned during the preparatory phase
on the dorsum of the tongue
action of the tongue during the preparatory phase
tip presses against max incisor or anterior hard palate
Region where bolus is positioned rises lateral against posterior teeth and palatal mucosa
when does the glossopalatal sphincter form
when the pharyngeal (posterior) part of the tongue rises and contact the soft palate and the soft palate pushes down
roll of the glossopalatal spinciter
prevents the bolus from entering the pharynx prematurely
does the glossopalatal sphincter exist for a long time
No, temporary
what happnens in the oral phase
Movement of the bolus from oral cavity to pharynx
time of the oral phase
about .5 seconds
what happens first in the oral phase
Lips close, upper and lower incisory move closer together
what does the Lips close, upper and lower incisory move closer together during the oral phase
to form an oral seal
what happens after the Lips close, and the upper and lower incisory move closer together
anterior 2/3 of the tongue moves up agianst the maxillary alveolar ridge and the anterior hard palate
consequence of the anterior 2/3 of the tongue moves up agianst the maxillary alveolar ridge and the anterior hard palate during the oral phase
pushes the bolus towards the pharynx
what happens after the anterior 2/3 of the tongue moves up agianst the maxillary alveolar ridge and the anterior hard palate during the oral phase
- base of tongue moves downward and forward
- palate moves
- palate contacts posterior pharyngeal wall and the wide wals of the nasopharynx are opposed
consequence of the base of tongue moving downward and forward during the oral phase
expands hyopharynx and opens a chute to the pharynx
what is the consequnce of the palate moving up during the oral phase
Opens the glossopalatal sphincter
what is the consequence of the palate contacting the posterior pharyngeal wall and side walls of the nasopharynx opposing during the oral phase
Prevents the bolus from entering the nasal cavity
what muscles are involved in the preparatory and oral phases of swallowing
Mandibular muscles (masseter, medial pterygoid, temporalis) Facial muscles (labial and buccinatory
are the muscles invovled in preparatory and oral phases always the same
Variable and facultative (depending on food consisteny)
what does the contraction of the labial and buccinatory muscles do
Form the oral seal and stabilize the mandible
what happens in the pharyngeal phaes
Movement of bolus from oropharynx to the esophagus
what happens first in the pharyngeal phase
Piston-like movement of the posterior tongue
what is the conseqeunce of the piston-like movment of the posterior tongue in the pharyngeal phase
Propels the bolus through the oropharynx and into the hypopharynx
what happens after the pirston-like movment of the posterior tongue during the pharyngeal phase
pharyngeal contrictors contract several times
what is the consequence of the pharyngeal constrictors contracting several times during the pharyngeal phase
moves the bolus through the pharynx
what happens after the pharyngeal constrictors contract sever times during the pharyngeal phase
Upper esophageal sphinctor opens
what does the upper esophageal sphincter opening lead to
Allows the bolus to enter the esophaus
whathappens after the upper esophageal sphinctor opens
Epiglottis movement (from upright to horizontal) caused by eleveation of thehyoid bone and larynx and contraction of the thyrohyoid muscle
consequence of the epiglottis moving from upright to horizontal
Closes the opening to the larynx
is the epiglottis absolutely required to prevent aspiration of food
No( removed in some people who can still swallow without aspiration
what stages use more consitent muscles, pharyngeal or prep/oral
Phayngeal
what are the muscles called in the pharyngeal phase of swallowing
Obligate group of muscles
what are the muscles called in the oral and prep phases
faculating
what groups of muscles are included in the obligate group
Leading complex of muscles
and others
what does the leading complex of muscles consist of
Mylohyoid geniohyoid etc
how does the leading complex of muscles act
contract fiarly synchronously
how do the muscles after the leading complex of muscles act
more sequential (thyrohyoid, thyroarytenoid, middle constrictor, cricothyroid, inferior constrictor)
what happens in the esophageal phase
movement of food along entire esophagus
how long is the eosphageal phase
3 sec for liquids
9 sec for solids
how does the bolus move during the esophageal phases
Peristaltic waves oof contraction (primarily smooth muscle)
what must open to allow bolus to enter stomach
Lower esophageal sphincter
activity of the esophageal sphincters
Tonically active
basal activity stops before bolus enters esophagus
when does the upper esophageal sphincter relax
when the tongue and the upper pharynx contract and is open before the pressure wave passes through the pharynx
when does the upper esophageal sphincter contract
after the food bolus enters the esophagus and its pressure rises well above resting level for several seconds
how long is the esophageal spincter relaxes
about 3 seconds before peristaltic waves reach it and until the last series of swallows is complete
how does the lower esophageal sphincter contract
for 1-2 seoncds so that developed pressure is well above the resting level
what prevents aspiration of food during the pharyngeal phase
Respiration inhibited
Larynx and upper esophageal sphincter elevate
Intrinsic muscles of glottus move vocal cords toward each other
Bolus moves through sinuses in pharynx
what phases of swallowing are voluntary and normally subconsious
Preparatory and oral phases
what phases of swallowing are involuntary
Phayngeal and esophageal phases
what is the swallowing center
The brain stem
what are the three components of the brain stems swallowing center
Sensory nuclei
Interneuronal network nuclei
Motor nuclei
what are the sensory nuclei of the swallowing center
Nucleus Tractus Solitarius
trigeminal sensory nucleus
what are the motor nuclei of the Swallowing center
Nucleus Ambiguous
Facial, trigeminal and hypoglossal nuclei
what does the interneuronal network do in the swallowing center
Mediates interactions between motor na dsensory nuclei
where is the interneuronal network found for the swallowing center
not discreet, rather distributed and ventral and dorsal medulla
what do dorsal internueoons do for the swallowing center
Initiation and programming (timing) of swallowing)
can the initiaiton and programming (timing) of swallowing occur without snesory input
Yes, but normally many afferent fibers send info to these interneurons through the NTS
what do ventral interneurons in the swallowing center do
Distribute the excitation to the swallowing motor nuclei
what not part of the brain stem swallowing center is also in control of swallowing
Cervical motoneurons
where does Afferent info of swallowing originate
In the pharynx, larynx, esophagus
where is afferent infor of swallowing send
To the NTS
what does afferent info during swallowing result in
Modulation of swallowing depending on food consistency
what may be inhibited due to activation of afferent fibers
some motoneurons (esophageal motoneurons during oral and pharyngeal phases
is the cortex needed for smooth efficient swallowing
cortex can initiate swallowing but not needed for smooth efficient swallowing
what mucles are programmed in utero for swollowing
Obligate muscles (timing and sequence of contraction, pharyngeal phase of swallowing)
how are facultative muscles patterned
before and after tooth eruption
BEfore tooth eruption what is invovled in sealing the oral caivty
Orbicularis oris and buccinator muscles (tongue thrust)
jaw closer muscles roll before eruption
Not prominent role
when do jaw closer muscles become involed
After tooth eruption
what muscles work less after tooth eruption
Labial and buccinator muslces (also tongue thrust)
what happens if the infantile style of swallowing is maintied after tooth eruption
Malocclustion(anterior open bite)
can babies breath while swollowing
No
Are infant and adult sucking differnt
Yes
Infant sucking occures how
Lips seal around nipple
Mandible lowered to make negative pressure
Elevation of jaw and tongue espresses the milk
what muscles have important roles in infant suckling
Jaw opening and jaw closing muscles
is respiration maintained during sucking episode
YEs
when does suckling begin
In utero
How does Adult sucking occur
Similar to inspiration through the mouth (driven by inspiratory muscle, not jaw muscles)
Purpose of emsis
Vomiting to rid stomach of contenets (Toxic)
stimuli for vomiting
- Physiological (pain,vestibular imbalance, distention or injury to stomac, intestine, bladder or uterus, iritiation of gut or peritoneus. substance in blood can directly stimulate chemoreceptors in medulla)
- disease releated (increase intracranial presss (heart attack), stenosis of pyloric valve, raditation therapy, anesthesia, psychological stress
Vomiting phases
Pre ejection
Retching
Expulsing
Post ejection
Characteristics of the pre-ejection phases of vomitign
Licking, salivation, tachycardia, and relaxiation of the proximal part of stomach
duration of the pre-ejection phase of vomiting
Few minutes to several days (pregnancy)
what happens during retching
Glottis closed
inspiratory muscles contract decreasing in intra-thoracic pressure and increse in intra-abdominal pressure
what happens to the upper esophageal sphincter during each retch
relaxes then contracts between each one
what happens during expulsion
Atrum of stomach relaxes
Rectus abdominus and external oblique contract
Upper esophageal sphincter relaxes
Intra-thoracic and intra-abdominal pressure rise to 100mmhg comared to resting 10 mmhg of lower esophageal sphincter
what happens in post ejection
Cycle can terminate or repeat several times
what coordinates vomiting act
Group of nuclei in medulla
where does the afferent info from stimuli to vomit terminate
In the sensory nuclei of the medullar complex
Direct stimulation near the NTS in animals causes what
Vomiting
what does the NTS connect to
Area postrema
what does the area postrema contain
Chemoreceptor trigger zone
what stimulates the chemorecptor trigger zone
Emetic agents in the blood
characteristiscs of bruxism
Forceful tooth clenching, grining during sleep
Rhythmic chewing, sustained contraction
what is similar to bruxxism in the day due to mandibular mech
Daytime tooth clench
oringially thought cause of bruxism
Interferences in occlusion (wrong because tooth stimulation leads to inhibition of jaw closerse
what shows that Bruxism has CNS origin
Certain sleep phases relating to stress
stimulation of certain brain areas have shown what for bruxism
Hypothalamus stimulation leads to stresss and excitation of jaw closer motoneurons
Consequences of bruxism
PAin, muscle damage
Tooth wera, mobility, fracture
TMD, headaches, remodeling of condyles if severe
how to treat brusims
Reduce stress
bite appliances
two major issues with TMD
pain and impaired chewing efficiency
do men or women have TMD
Women have more TMD with more pain while guys have more problem chewing and jaw opening
do old people have TMD
lower probablity
what Might TMD be a part of
TM (fibromyalgia) -more common in women, muscular pain, and depression
similar treatment
why might TMD not be part of FM
FM more common in old
