oral physiology Flashcards
genioglossus muscle
extrinsic tongue muscle. very fast with high amount of fast twitch fibers
what are the jaw opener muscles
- digastric2. lateral pterygoid (technically a PROTRACTOR)3. geniohyoid4. mylohyoid
digastric muscle is composed of mostly what type of fibers
fast
dysfunction of the superior head of the lateral pterygoid is associated with what
anterior displacement of the TM disc in TMJ dysfunction
there is a ___ amount of force generation needed for the jaw opening muscles
low amount of force generation….more important for movement instead of force production
what are the jaw closer muscles
- masseter2. temporalis3. medial pterygoid
the masseter muscle is composed of mostly what type of fibers
slow fibers (in both the deep and superficial parts)
what myosin isoforms predominate in the adult for the masseter muscle
slow fibers
what myosin isoforms predominate in the neonatal/embryonic masseter muscle
alpha cardiac
bruxing leads to ____ of the muscle
hypertrophy (gets larger)
bruxing hypertrophy leads to an increase in what
increase in the level of slow myosin…which could create less powerful contractions of the masseter which could affect chewing/speech/etc
the temporalis muscle is composed of mostly what type of fibers
faster type myosin than the masseter
the medial pterygoid muscle is composed of mostly what type of fibers
slower myosin
what is the pattern among jaw closer muscles (masseter, med pterygoid, temporalis)
compartmentalization….where there is greater amount of slow myosin fibers in the anterior and deep layers and faster myosin fibers in the posterior and superficial
what is kinesthesia
sense of movement and position
what provides feedback from the muscles to the CNS
rich sensory information is provided from the masticatory muscles to the CNS via sensory afferents. feedback can then be delivered from the CNS back to the masticatory muscles (to better control force generation and precision).
what are the two types of muscle fibers that make up a muscle spindle
- nuclear bag intrafusal fibers (clustered nuclei in the center of the fiber)2. nuclear chain intrafusal fibers (nuclei arranged in a chain/linearly within a fiber)
intrafusal refers to what
fibers that are WITHIN a muscle spindle rather than extrafusual fibers which are the muscle fibers that generate the “work” of a muscle during contraction (and are outside of the muscle spindle)
what are the 2 types of efferent nerve fibers associated with a muscle spindle
gamma and beta (rare)
what is the job of the efferent nerve fibers associated with a muscle spindle
to innervate the intrafusal fibers of the spindle
what are the 2 types of sensory/afferent nerve fibers associated with a muscle spindle
- 1a afferent/primary ending2. II afferent/secondary endings
what is the job of the sensory/afferent nerve fibers of the muscle spindle
they adjust the incoming signal to the muscles by providing info to the CNS about what is going on w/in the muscle. the CNS needs to know what to tell the extrafusal fibers to do.
what is the difference b/w Ia and IIa afferent fibers
-Ia provide MORE DYNAMIC signals (report to CNS earlier and give a more “robust” signal) to the CNS, but their signal DISSIPATES more during the length of a muscle stretch -IIa have a delayed response to the stimuli applied, but provide the signal more CONTINUOUSLY throughout the muscle stretch
what is the role of gamma efferent fibers within a muscle spindle
to maintain a high level of spindle sensitivity in SHORTENED muscles. when a muscle shortens, the gamma efferents signal to the intrafusal fibers (that they innervate) to shorten in their POLAR regions (outside of the muscle fiber). shortening of the polar region of intrafusal fiber causes lengthening of the equatorial (central) region of the muscle spindle. lengthening of the equatorial region of the spindle RESTORES THE SENSITIVITY of the spindle to future stretch stimuli
what would happen if the spindle didn’t “reset” its sensitivity after muscle shortening?
bc the spindle could not restore its sensitivity, the muscle (extrafusal fibers) would keep working over a range of short lengths where the spindles would remain inactive and not be able to send modulating info to the CNS (….assuming this could result in injury of some kind?)
what are golgi tendon organs
receptors located in jn b/w the ends of muscle fibers and tendon (located w/in the tendon in series with muscle fibers). they generate signals that are proportional to the amount of force generated by the extrafusal (working) muscle fibers
how does a GTO respond to increasing forces
the more force applied/done by the extrafusal fibers, the more tension applied to the GTO and theremore the more a.p produced by the GTO
what are free nerve endings in joints activated by….what doe they respond to
mostly activated by PAIN, but some activated by mechanical stimuli (to sense joint position)
what is an EMG
non invasive gathering of info that records and analyzes muscle activation patterns. they don’t reflect forces generated across a joint (bc antagonist muscles can create a net 0 force).
how can an EMG be clinically relevant?
see what muscles are activated or no longer activated after unilateral damage/surgery has been perfomed (i.e a unilater marginal madiblectomy…aka mandible removed on one side)
depending of food consistency, mandibular movements during mastication are both ____ and _____
highly rhythmic and specific (controlled by the CNS!)
what are the 4 phases of CHEWING
- slow opening2. fast opening3. fast closing4. slow closing (to protect teeth/soft tissues)**this is highly CONSISTENT across species (even if they have different feeding behaviors)
the type of ____ differs b/w species with different feeding behaviors
myosin!carnivores–> masticatory herbivores–> alpha cardiac (rhythmic) omnivores–> unspecialized
what are the 3 phases of MASTICATION
- preparatory2. reduction3. pre-swallowing**variable activities of the openers and closers in ALL phases
characteristics of the preparatory phase
NAME?
characteristics of the reduction phase
NAME?
characteristics of the pre-swallowing phase
NAME?
what are the primary sites of control for mastication
- brainstem2. cerebral cortex3. and a little bit of the cerebellar cortex**these both include: nuclei, afferent fibers, and efferent fibers
the sensory nuclei that control mastication include
- trigeminal sensory nucleus2. trigeminal mesencephalic nucleus
what is the role of the trigeminal sensory nucleus
fibers extending from here INNERVATE the face and oral cavity (sensory) and then PROJECT to the cerebellar and cerebral cortexs
what is the role of the trigeminal mesencephalic nucleus
fibers extending from here are coming from the:1. spindle afferents of jaw closers2. mechanoreceptors in the PDL/ gingiva/palate
the motor nuclei involved in the control of mastication include
- trigeminal motor nucleus2. hypoglossal motor nucleus3. facial motor nucleusCN V, XII, and VII
what is the role of the trigeminal motor nucleus
includes alpha and gamma MOTOR fibers that innervate the jaw muscles. TOPOGRAPHIC organization
what is the role of the hypoglossal motor nucleus
includes the MOTOR fibers that innervate the tongue muscles
what is the role of the facial motor nucleus
includes the MOTOR fibers that innervate the facial muscles. TOPOGRAPHIC organization
the motor nuclei and sensory nuclei that control mastication are located where
brainstem
what is the role of the brainstem in mastication
fn autonomously. may contain a pattern generator. doesn’t require (although normally does) input from higher centers.
describe the jaw closing reflex
- afferent fibers from muscle spindles send a signal to…2. trigeminal mesencephalic sensory nucleus which sends fibers to the…. 3. trigeminal motor nucleus to synapse here on…4. alpha motor neurons which innervate…5. extrafusal fibers of the jaw muscles (to close the mouth!)
the jaw closing reflex is
monosynaptic…making it very fast (w/ very little modulation)
describe the jaw opening reflex
- a stimulus in the oral cavity activates afferents that send a signal to….2. spinal trigemnal tract nucleus which sends fibers to the…3. interneurons that are located within the CNS which then send fibers to the…4. trigeminal motor nucleus to synapse here on…5. alpha motor neurons which innervate6. extrafusal fibers of the jaw muscles (to open the mouth)
the jaw opening reflex is
polysynaptic…bc it is highly modulated for specific stimuli (depending on the stimuli size/consistency/etc)…causing it to take longer to execute
what is the role of “higher centers” in mastication
modulation of mastication
what is the role of afferents in mastication
modulation of mastication (depending on stimuli/food consistency). variable receptors involved with the input/food stimuli type. afferents give input to brainstem and higher centers (cortex)
what are the phases of swallowing (4)
- prepartory2. oral 3. pharyngeal 4. esophageal
preparatory phase of swallowing is the same as the…
pre-swallowing phase of mastication
the prep phase of swallowing is a fn of the
glossopalatal sphincter
what is the glossopalatal sphincter and what is it composed of
a temporary sphincter composed of the posterior tongue and the soft palate (when they contact). it prevents food bolus from entering the pharynx.
describe the prep phase of swallowing
- bolus formed and resting on tongue2. tip of tongue presses against max incision/ant hard palate3. region of tongue where food positioned rises laterally against pos teeth and palate4. palatoglossal sphincter forms
what is the oral phase of swallowing
movement of the bolus from the oral cavity to the pharynx….but food still in the oral cavity
describe the oral phase of swallowing
- formation of oral seal (as incisors and lips move close together)2. bolus is pushed toward the pharynx (ant tongue touches max alveolar ridge and ant hard palate)**3-5 occur TOGETHER!3. expansion of the hypopharynx to open “chute” to pharynx (tongue base moves down and forward)4. glossopalatal sphincter opens (palate moves up)5. food is prevented from going into nasal cavity (side walls of nasopharynx are close as palate contacts the pos pharyngeal wall)
what are the muscles involved in the prep and oral phases of swallowing
- jaw closers2. facial muscles (formation of oral seal and stabilizes mandible)** FACULTATIVE GROUP of muscles (variable bc depends on food consistency)
what is the pharyngeal phase of swallowing
movement of bolus from oropharynx to esophagus
describe the pharyngeal phase of swallowing
- food is propelled by the posterior tongue from the oropharynx to the hypopharynx 2. food moves through pharynx by contraction of pharyngeal constrictors3. bolus enters the esophagus as upper esophageal sphincter relaxes4. opening to larynx closes as the epiglottis moves to a horizontal position
is the epiglottis required to prevent aspiration
no
what components allow for the movement of the epiglottis
hyoid bone (up), larynx (up), thryohyoid (contraction)
what muscles are involved in the pharyngeal phase of swallowing
OBLIGATE group of muscles ….sequential in order of contraction
what is the esophageal phase of swallowing
movement of food along entire esophagus
describe the esophageal phase of swallowing
- peristaltic waves of contraction to move bolus2. lower esophageal sphincter opens3. food enters stomach
the esophageal sphincters are ____ active
tonically active! they are are “inactivated” by BASAL ACTIVITY normally…but the basal activity stops before food enters the esophagus
describe the contraction/relaxation of the upper esophageal sphincter
the upper is relaxed/opened before the pressure waves pass through the pharynx (to allow for food to pass through). then the upper contracts/closes after the bolus enters the esophagus. here, its pressure rises well above resting for a few seconds (to force food down)
describe the contraction/relaxation of the lower esophageal sphincter
the lower is relaxed/open before the peristaltic waves reach it and remain relazed until the last series of swallows is complete. the lower then contracts/closes after last swallow. here, its pressure rises well above resting for a few seconds.
what are the mechanisms the prevent aspiration
NAME?
which phases of swallowing are involuntary
pharyngeal (3) and esophageal (4)
which phases of swallowing are voluntary
preparatory (1) and oral (2)….but normally subconcious
what are the 3 components of the brainstem swallowing center
- sensory nuclei2. interneuronal network nuclei3. motor nuclei
what are the 2 sensory nuclei of the brainstem involved in swallowing
- nucleus of the solitary tract2. trigeminal sensory nucleus**this is where the info comes in that says what/where/and what consistency the food is
what are the 2 motor nuclei of the brainstem involved in swallowing
- nucleus ambiguous2. facial/trigeminal/hypoglossal nuclei (same as mastication)
what is the interneuronal network of swallowing for
to mediate the interactions b/w the sensory and motor components of swallowing.
where is the interneuronal network for swallowing located
distributed in the ventral and dorsal regions of the medulla
what are the dorsal interneurons of the interneuronal network for swallowing for
initiation and programming/time of swallowing….can occur in the absence of sensory input. normally receives input from the nucleus of the solitary tract.
what are the ventral interneurons of the interneuronal network for swallowing for
distribution of the excitation to the swallowing motor nuclei (nucleus ambiguous and CN V, VII, XII nuclei)
cervical motor neurons are involved in what
control of swallowing…although not part of the brainstem swallowing center
where does sensory info originate from during swallowing
pharynx, larynx, esophagus….afferents are sent to:-nucleus of solitary tract
stimuli during swallowing can
activate afferent fibers to activate motor neurons or activate afferent fibers to INACTIVATE motor neurons (i.e the esophageal motor neurons are inactivated during oral and pharyngeal phases of swallowing)
role of cortex in swallowing
can initiate swallowing if stimulated…but, not required for smooth, efficient swallowing
describe the programming of infantile swallowing
NAME?
describe the programming pattern of facultative muscles of infantile swallowing BEFORE tooth eruption
NAME?
describe the programming pattern of facultative muscles of infantile swallowing AFTER tooth eruption
NAME?
what is the consequence if infantile swallowing before tooth eruption is maintained even after tooth eruption
malocclusion…anterior open bite (from tongue thrust). controversial
can infants swallow without interrupting respiration
no
describe infant suckling mechanism
- lips around nipple-mandible lowered-negative pressure in infants mouth-elevation of tongue and mandible =milk**so here, jaw opener and closer muscles are IMPORTANT
is respiration maintained during infant suckling
yes!
when does infant suckling programming begin
in utero
describe the adult sucking mechanism
-driven by inspiratory muscles (think of sucking on a water bottle and get your heads out of the gutter)-lips form seal, but jaw opener/closer mm DON’T have a role in generating forces
what is emesis
vomiting
stimuli for vomiting
- physiological stimuli (**wine at psi thanksgiving dinner)2. disease-related stimuli
what are the phases of vomiting (3)
- pre-ejection2. ejection3. post-ejection
pre-ejection phase of vomiting
relaxation of proximal stomach (along with licking, salivation, tachycardia). duration can be min–>days
ejection phase
2 phases (retching and ejection)
describe the retching phase of the ejection phase of vomiting
glottis closed and inspiratory mm contract to…1. decrease thoracic pressure and 2. increase abdominal pressure3. upper esophageal sphincter relaxes during a “retch” but contracts b/w each one (1-2 sec apart)
describe the expulsion phase of the ejection phase of vomiting
antrum of stomach relaxes, ab mm. contract, upper esophageal sphincter relaxes 1. thoracic pressure rises2. abdominal pressure rises 3. lower esophageal sphincter pressure is LOWvomit can travel from high pressure to low pressure…lovely.
post-ejection phase of vomiting
cycle terminates of repeats
what controls vomiting
medulla nuclei….info is brought in from (physiological or disease-related) stimuli via afferents to the sensory nuclei in the medulla
bruxism causes
sleep phases….aka has a CNS origin… correlated with stress levels…excitation of jaw-closer motor neurons
why is bruxism NOT due to occlusion interferences
tooth stimulation (caused by malocclusion) causes inhibition of jaw-closers
