Oral functions Flashcards
What is the origin, insertion and action of the masseter muscle
Origin - zygomatic arch
Insertion - lateral surface and angle of mandible
Action - elevates mandible
How do you examine the masseter muscle
Place one finger
intra-orally and the
other on the cheek
When would a patients masseter muscle be tender
In patients who have a clenching habit
What is the origin, insertion and action of the temporalis
Origin - floor of temporal fossa
Insertion - coronoid process and anterior border of ramus
Action - elevates and retracts mandible
What muscle is affected by a bruxist habit
Temporalis
How is the temporalis examined
Palpate its origin by asking the
patient to clench the teeth
together.
What is the origin, insertion and action of the lateral pterygoid
Origin: from the lateral surface of the lateral pterygoid plate
Insertion: anterior border of the condyle and intra-articular disc via two independent heads
Function: protrudes and laterally deviates the mandible and the inferior head functions with the mandibular depressors during openings.
Where does the inferior and superior belly of the lateral pterygoid attach to th condyle
The inferior belly of the lateral pterygoid
attaches to the head of the condyle.
The superior belly inserts into the intra articular disc
How is the lateral pterygoid examined
Best examined by recording its response to
resisted movement. (ask patient to push jaw against pressure)
There is a good correlation between the
resisted movement test and the muscle being
tender to palpation.
What is the origin, insertion and action of the medial pterygoid
Origin - deep head: medial surface of lateral pterygoid plate ; superficial head: tuberosity of maxilla
Insertion - medial surface of angle of mandible
Action - elevates and assists in protrusion of the mandible
How is the medial pterygoid examined
There is no reliable way of examining this muscle
Following a LA injection if a patient cannot fully open their mouth the next day what muscle was hit
Medial pterygoid
What is trismus
Lockjaw, chewing muscles become contracted and inflamed
What are the movements of the TMJ
Rotation - initial opening Translation - wider opening
What TMJ movement is needed for protrusive and retrusive movements
Translation
What is the movement of the condyles during protrusion and retrusion
As the mandible moves during
protrusion, both condyles leave their
fossae and move forward along the
articular eminences.
When the mandible retrudes, both
condyles leave the eminences and
move back into their respective fossae
Who discovered the extent of the mobility of the mandible
Ulf Posselt
What is the maximum biting and clenching forces
Varies between teeth
* Maximum between
molars (200-700N)
What is the world record biting force
4300N
What factors affect max bite force
Psychological
-fear of breaking teeth
Muscle mass
-bigger muscles
Muscle fibre types
Type I– Slow, low forces
Type II– Fast, stronger forces,
Sub-types (IIA, IIX, IIB)– Predominant fibre type
varies, depending on jaw morphology, diet
Evidence that people with ‘squarer’ jaws, have more
Type II fibres and can generate stronger bite forces
Tooth type and position
-Position relative to TMJ (molars are nearer the force so can appy more force)
What is the different between muscle fibre types in the mandible
Type I– Slow, low forces
Type II– Fast, stronger forces,
Sub-types (IIA, IIX, IIB)– Predominant fibre type
varies, depending on jaw
morphology, diet
Where is the greatest bite forces generated
Between 1st molars
What are the suprahyoid muscles
- Digastric
- Mylohyoid
- Geniohyoid
- Stylohyoid
What are the infrahyoid muscles
-Sternohyoid
–Omohyoid
–Thyrohyoid
–Sternothyroid
What is another name for infrahyoid muscles
‘Strap’ muscles
What muscles act as jaw depressors when the hyoud bone is fixed
– Digastric
– Mylohyoid
– Geniohyoid *
What are the intrinsic tongue muscles and their function
Alter shape
-longitudinal
-vertical
-transverse
What are the extrinsic tongue muscle and their function
Alter shape and position
Genioglossus
Hyoglossus
Palatoglossus
Styloglossus
What facial muscles helpmaintain food in the oral cavity
Orbicularis oris
Buccinator
What cranial nerve provides sensory innervation to the mandible
Trigeminal nerve
What branch of the trigeminal nerve innervates the molars
Mandibular division
Inferior alveolar nerve
Where does the trigeminal nerve stem from
Brainstem
What nerve supplies sensory function to anterior mandibular teeth
Mental nerve (stems from inferioralveolar nerve)
Where does the mental nerve exit the mandible
Mental foramen
What is the ID nerve
Inferior alveolar nerve (inferior dental nerve)
Where does the inferior alveolar nerve enter the mandible
Lingula
What is paraesthesia
an abnormal sensation, typically tingling or pricking (pins and needles)
What is dysaesthesia
an abnormal unpleasant sensation felt when touched, caused by damage to peripheral nerves
What is the Gagging reflex and how is it brough about
Acts to prevent material entering pharynx
Evoked by mechanical stimulation of fauces, palate, posterior
tongue, pharynx
Similar to vomiting, but there is no ejection of material
Some patients gag when instruments and/or materials are placed in
the mouth
When is gagging reflex a clinical problem
When patients have an oversensitive gag reflex
What nerves are involved in the gagging reflex
Motor (efferent) response from V,IX,X,XI,XII
Sensory (afferent) response from IX
The motor visceral nerves of the salivary glands are also stimulated
By name which cranial nerves are involved on the gagging reflex
Trigeminal
Glossopharyngeal
Vagus
Accessory
Hypoglossal
How is a RPD designed to reduce risk of gagging in oversensitive patients
Constructed with a retaining mesh tofacilitate the attachment of acrylic extension which can be adjusted more easily
Magnets can be used to hold it in place
When is facial paralysis classed as bell’s palsy
Bell’s palsy is coined for any type of facial paralysis that does not have any other associated causes such as tumors, trauma and salivary gland inflammation
What facial muscles are particularly impacted with bell’s palsy
Orbicularis oris
Buccinator
What are some causes of Bell’s Palsy
Infections(HSV/Cold sores)
Otitis media (middle ear infection)
Diabetes
Trauma
Temp infiltration of LA to the facial nerve branches
How can injection of LA cause Bell’s Palsy
occurs when the injection is given too far distally and the parotid gland is penetrated,
allowing the diffusion of the LA through loose glandular tissue, which then affects all
five terminal branches of the facial nerve.
How should temporary palsy be treated after injection causes the complication
Tell the patient and reassure it is temporary and give an eye patch to protext the cornea until protective blink reflex returns
Why is extraction of viable teeth to make a full denture not recommended
While the roots and their periodontal ligaments remain, periodontal mechanoceptors allow finer discrimination of food texture, tooth contacts and levels of functional loading
A better a appreciation of food and
a more precise control of mandibular movements than is provided by full dentures.
What is the alternative for a patient wanting full dentures but still has a few viable teeth
Periodontal machenorecptors overdentures
-Keep periodontal ligaments with remaining teeth so more precisse control of mandibular movements and finer discrimination of food texture
What does the loss of periodontal mechanoreceptors influence
the control of jaw function
the precision of magnitude
direction
rate of occlusal load
application
What oral functions do periodontal mechanoreceptors contribute to
Mastication (food consistency) Salivation
Interdental discrimination
What is interdental discrimination
- Ability to gauge extent of mouth opening
- Coordination of masticatory movements
- Monitoring size of food particles
- Detection of ‘high’ spots
- Foil thresholds 8-60μm
What can cause dysphagia
- stroke
- brain injury
- multiple sclerosis
- gastroesophageal reflux disorder
- tumours
Why do smelling disorders often affect the sense of taste
The sense of smell stimulates salivary glands
