Oral functions Flashcards by Niamh Sands

What is the origin, insertion and action of the masseter muscle

Origin - zygomatic arch
Insertion - lateral surface and angle of mandible
Action - elevates mandible

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How do you examine the masseter muscle

Place one finger
intra-orally and the
other on the cheek

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When would a patients masseter muscle be tender

In patients who have a clenching habit

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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

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What muscle is affected by a bruxist habit

Temporalis

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How is the temporalis examined

Palpate its origin by asking the
patient to clench the teeth
together.

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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.

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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

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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.

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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

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How is the medial pterygoid examined

There is no reliable way of examining this muscle

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Following a LA injection if a patient cannot fully open their mouth the next day what muscle was hit

Medial pterygoid

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What is trismus

Lockjaw, chewing muscles become contracted and inflamed

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What are the movements of the TMJ

Rotation - initial opening Translation - wider opening

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What TMJ movement is needed for protrusive and retrusive movements

Translation

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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

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Who discovered the extent of the mobility of the mandible

Ulf Posselt

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What is the maximum biting and clenching forces

Varies between teeth
* Maximum between
molars (200-700N)

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What is the world record biting force

4300N

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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)

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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

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Where is the greatest bite forces generated

Between 1st molars

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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