oral function and dental development p253 Flashcards
masseter
origin
zygomatic arch
masseter
insertion
lateral surface and angle of mandible
masseter
action
elevates mandible
masseter
exam
place one finger intre orally adn other on the cheek
temporalis
origin
floor of temporal fossa
temporalis
insertion
coronoid process and anterior border of ramus
temporalis
action
elevates and retracts the manidible
temporalis
exam
tender in bruxist
palpate origin and get pt to clench
digital palpation between superior and inferior temporal lines
just above the ear
extend forwards towards supra-orbital region
lateral pterygoid
origin
lateral surface of the lateral pterygoid plate
lateral pterygoid
insertion
inferior head - anterior border of the head of the condyle
superior head - intra articular disc of the TMJ
lateral ptergygoid
action
protrudes and laterally deviates the mandible
inferior head acts with madnibular depressors to open mouth
lateral ptyegoid exam
n/a for palpation
can exam resisted movement
resist lateral and vertical movement
medial pterygoid
origin
deep head - medial surface of lateral pteygoid plate
superifical head - maxillary tuberosity
medial pterygoid insertion
medial surface angle of the mandible
medial pteygoid action
elevates and assists in protrusion of the mandible
medial pterygoid exam
n/a no reliable way to perform
if hit by LA causes trismus
role of buccinator and orbicularis oris
prevent spillage of bolus and control its placement in the mouth
strap muscles a.k.a
infrahyoid muslces
infrahyoid muscles
TOSS
thryohyoid
omohyoid
sternohyoid
strenothyroid
suprahyoid muscles
mylohyoid
digastric
geniohyoid
stylohyoid
My Dog Gets Shy
intrisic tongue muscles
longitudinal
vertical
transverse
extrinsic tongue muscles
hyoglossus
styloglossus
palatoglossus
movement in upper compartment of TMJ
gliding
movement in lower compartment of TMJ
rotating
neurons
afferent
sensory
carry message to CNS
going towards brain or spinal cord
neuorns
efferent
motor
carry message to muscle, gland or other effector
carry message away from CNS
interneurons
connecting
one neuron to another
multiple interneurons in reflexes
connect sensory to motor
CN involved in gag reflex
V
IX
X
XI
XII
gag reflex
acts to prevent material entering the pharynx
gag reflex evoked by
mechanical stimulation of
- fauces
- palate
- posterior tongue
- pharynx
gag reflex has efferent response from
CN V, IX, X, XI, XII
visceral nerves of salivary glands
how to manage gag reflex in RPD
CoCr mesh at post dam region to reduce mucosal coverage
reduce the weight of a large connector
signs of Bells palsy
- inability to wrinkle brow
- drooping of eyelid
- inability to close eye
- inability to puff cheeks - no muscle tone
- drooping of mouth, food stuck in cheek
branches of facial nerve
temporal
zygomatic
buccal
mandibular
cervical
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facial nerve is
CNVII
causes of bells palsy
infections (HSV/Cold sores)
otitis media (inflammation of middle ear)
diabetes
trauma
toxins
temporarilu by infiltration of LA to facial nerve branches
- inject to far distally
- parotid gland is penetrated
- allows diffusion of LA through loose glandular tissue
- affects 5 terminal branches of facial nerve
oropharyngeal dysphagia
pt has feeling of things being stuck in throat
difficulty swallowing
often associated with achalsia (faily of parasymp ganglion for oesphageal wall) -> failure of peristalsis
aetiology of dysphagia
stroke
brain injury
multiple sclerosis
GORD
tumors
5 types of receptors
mechanoreceptors
thermoreceptos
nociceptors
proprioceptors
chemoreceptors
mechanoreceptors
Have a low thresholds, allowing the senses of touch and pressure (0.5mN)
Adapt to constant stimulus- they are slow and adapting types
TMJ receptors, Muscle receptors, PDL receptors
Periodontal Mechanoreceptors
- Sensitive 10-100mN
- They display directionality > Can percieve direction of pressure
- Used in food texture discrimination
- Tooth contacts
- functional loading
DETECTION OF HIGH SPOTS!* - can detect down to half the thickness of a human hair
*remember scenario that shows benefits of keeping teeth in rpd for mechanorecptive use
> loss of periodontal mechanoreception precludes to
= poorer jaw control
= poorer precision of bite force magnitude
= poorer perception of direction
= rate of occlusal load application
thermoreceptors
Cold Thermoreceptors
- increase firing with a decrease in temperature [Aδ and C fibres]
- located at dermal-epidermal junction
Hot Thermoreceptors
- increase firing with an increase in temperature [C fibres]
- located in dermis
nociceptors
Free nerve endings with high thresholds
respond to intense stimuli associated with pain
- > Aδ fibres - Noxious mechanical and heat stimuli
- > C fibres - Polymodal
Carry receptor proteins responsive to different noxious stimuli
proprioceptors
‘Self sense’
Awareness of position and orientation of body parts
Types include
- Joint receptors
- Joint position (mouth open/closed)
- joint movement (opening/closing)
- useful in controlling movements e.g chewing
- Muscle receptors
- Golgi Tendon organs
- Muscle spindles
- Periodontal receptors
chemoreceptors
e.g. taste buds, olfactory
Sense of smell stimulates salivary glands – smelling disorders often affect the sense of taste
In Nasopharyngeal infection a loss of smell (Anosmia) may be present
Patients have a difficulty discerning between taste and olfaction
4 stages in feeding sequence
ingestion
transport
mechanical processing
food processing
ingestion
Movement of food from external environment > mouth
Accomplished by biting (anterior teeth) and/or using ‘tools’ (cutlery, cups, etc)
Lips provide anterior oral ‘seal’
- Orbicularis Oris
- Buccinator
transport in feeding sequence
Moving material from the front of the mouth to the level of the posterior teeth
- Food is gathered on tongue tip
- Tongue retracts pulling the material to the posterior teeth (pull back processs) > takes 1 second
- Hyoid bone retracts > oropharynx narrows
mechanical processing in feeding sequence
Some solid foods must be broken down and mixed w/ saliva before they can be swallowed
Moist solid foods (e.g fruits) have to have fluid removed before transport and swallowing
Food masticated by pre-molars and molar teeth
some soft foods are squashed by tongue against hard palate
food processing in feeding sequence
Involves co-ordination of muscles
- Muscles of mastication
- Tongue Muscles
- Lips and cheeks
- Supra hyoid muscles
tongue role in food processing
- controls the bolus
- gathers food and rotates to reposition the bolus on the occlusal table
- along with cheeks it keeps the bolus on the chewing surfaces
- moves the bolus side to side of the mouth
- gatehrs bolus for transport
during occlusal and inital opening phases of eating the tongue contacts the hard palate
- contact point moves progressively backwards squeezing bolus through fauces
- SQUEEZE BACK MECHANISM
squeeze back mechanism
tongue
during occlusal and inital opening phases of eating the tongue contacts the hard palate
- contact point moves progressively backwards squeezing bolus through fauces
key difference between ingestion of solids and liquids
Solids
- accumulate on pharyngeal tongue until swallowing (with the mouth being continues with the oropharynx)
Liquids
- posterior oral seal acheived during ingestion i.e because liquids are swallowed from the mouth
chewing
Jaw joint = Nutcracker hinge
Anterior teeth = Near nutcracker handles
Posterior teeth = Near hinge
if Nut far away from hinge it will require extra force to crack if it cracks at all
If the nut is close to the hinge it cracks easily
- Hence why first molars have the maximum bite force (due to position and PDL attachment)
natural prevention of reflux
Elevation of soft palate
Tongue (sides) contacts pillars of fauces
Tongue (dorsum) contacts posterior pharyngeal wall
Upper oesophageal sphincter
- Reflux from oesophagus into pharynx
Lower oesophageal sphincter
- Reflux from stomach into oesophagus
*If not prevented tooth erosion can result
airway protection
Upward and forward movement of larynx
Closure of laryngeal inlet
- aryepiglottic muscles – epiglottis
Adduction of vocal folds
Stop breathing (apnoea)
dysphasia
specific language disorfer
involving damage to particular parts of brain (Broca’s area; Wernicke’s area)
dysphagia
swallowing problems
dysarthria
difficultuy speaking caused by muscles used in speech
language and speech defects due to
neuromuscular defects
Lesions in descending neural pathways
➡ Cranial nerves
➡vocal muscles
➡neuromuscular junctions
oral causes of language and speech issues
Anterior Open Bite
- Tongue thrusting
- Digit sucking
- skeletal origin
- Loss of teeth
- Cleft Lip
- Cleft Palate
- Nasal quality
- Oral and Nasal cavities not separated
Tongue Conditions
- Tongue tie
- Partial atrophy
- Tongue stud
Xerostomia
- Impeded speech due to inadequate saliva
- not solved by simply swallowing then speaking
Torus palatinus and Torus Mandibularis
- Bony protrusion either on palate or floor of mouth
Denture related
- Restricted tongue space!!
- Denture base too thick?
- artificial Teeth not set properly (tilting lingually?)
- Wrong occlusal planes > produces fricative!
consontants sounds produced by
partial or complete stoppage of airflow
fricatives sounds made
escape through air constriction
missing maxillary incisors can impair fricative soudns, edge should touch vermillion border of lower lip
plosives sounds made
sudden release after complete stoppage of airflow (‘stop’ consonants)
nasals sound made
air flows through nose
vowels sound made
continous airflow
shape of mouth varies
tongue position main factor
tooth origin
Ectoderm - Enamel Organ
Ectomesenchyme (Part of the Neural Crest) forms between the ectoderm and neural tube -
- Dental Papilla (Dentine and Pulp)
Mesenchyme - Dental Follicle
- Cementum
- PDL
WHOLE STRUCTURE OF - EO, DP and DF = TOOTH GERM
ectoderm ->
enamel
ectomesenchyme ->
dental papilla (denine and pulp)
mesenchyme ->
dental follicle (cementum and PDL)
5 stages in tooth development
initiation
morphogenesis
cytodifferentiation
matrix secretion
root formation
initiaion in tooth development
Maxillary process formed
Stomodaeum formed
mandibular process formed
- Primary Epithelial band forms at 6w IUL on the stomodeum
- This then progresses into the Dental Lamina at 7w IUL it splits into the
- Vestibular lamina from which the buccal sulcus develops
- Dental lamina from which the enamel organ develops
morphogenesis in tooth development
Bud’ stage
- Dental Lamina thickens (A) - Enamel Organ
- ectomesenchymal condensation (B) - Dental Papilla
‘Cap’ stage
- Enamel organ forms a cap over the papilla
- External Enamel Epithelium
- Internal Enamel Epithelium
- Meet at cervical loop
cytodifferentiation in tooth development
‘Early ‘Bell stage’
- More cell layers differentiate to form a complex enamel organ
- IEE
- EEE
- Stratum intermedium
- Stellate reticulum
Tooth shape is more defined
matrix secretion in tooth development
Late ‘Bell stage’
- Crown stage well defined
- Apposition of enamel and dentine begins
Dental Papilla cells adjacent to the IEE differentiate into odontoblasts
Odontoblasts lay down dentine matrix which is later mineralised
Once dentine formation has begun IEE differentiates into ameloblasts to form enamel
‘Induction’
- Dentinogenesis
- Odontoblast differentiation from IEE
- Deposition of the Dentine matrix (mainly collagen)
- This unmineralised dentine is predentine
- Mineralised dentine is by HAP
- Amelogenesis
- Ameloblast differentiation
- Dentine induces IEE cells to differentiate into ameloblasts
- They elongate becoming columnar
- The nucleus then migrates to the basal end of the cell
- Secretory phase
- Ameloblasts become secretory cells
- They synthesis and secrete enamel matrix proteins (amelogenins)
- Matrix is then partially mineralised (30% mineral)
- Ameloblast differentiation
- Maturation phase
- Most of the matrix proteins are removed
- Leaving room to increase the mineral content of enamel
- Mature enamel is 95% enamel
- Protection phase
- Ameloblasts regress to form a protective layer (the reduced enamel epithelium)
- Involved in eruption
- Formation of epithelial attachment
dentinogenesis
- Odontoblast differentiation from IEE
- Deposition of the Dentine matrix (mainly collagen)
- This unmineralised dentine is predentine
- Mineralised dentine is by HAP
amelogenesis
Ameloblast differentiation
- Dentine induces IEE cells to differentiate into ameloblasts
- They elongate becoming columnar
- The nucleus then migrates to the basal end of the cell
Secretory phase
- Ameloblasts become secretory cells
- They synthesis and secrete enamel matrix proteins (amelogenins)
- Matrix is then partially mineralised (30% mineral)
Maturation phase
- Most of the matrix proteins are removed
- Leaving room to increase the mineral content of enamel
- Mature enamel is 95% enamel
Protection phase
- Ameloblasts regress to form a protective layer (the reduced enamel epithelium)
- Involved in eruption
- Formation of epithelial attachment
root formation in tooth development
Crown formation must be fully completed before root formation
Then enamel organ maps out the shape of the crown
The EEE and IEE meet at the cervical loop
Migration of the cervical loop maps the crown shape
The root shape is defined by apical growth of the cervical loop which is now called hertwig’s epithelial root sheath
- It is a 2 cell type layered structure not 4 like the enamel organ
Process
- Hertwig’s Epithelial root sheath (HERS) induces formation of root dentine
- Then once the initial layer of root dentine is made HERS breaks up (as there is no enamel in the root)
- Remnants of HERS persist as the Epithelial cell rests of Malassez
- Mesenchymal cells from the follicle contact the dentine and differentiate into cementoblasts which form cementum
- Fibres from the developing PDL are embedded in the cementum ‘Sharpey’s Fibre’s’
