Oral Functions

Question 0

What happens during the first stage of feeding?

Answer 0

Ingestion stage. Movement of bolus from external environment to internal environment. Accomplished with aid of oral seal.

Question 1

What are the five stages of feeding?

Answer 1

Ingestion, stage one transport, mechanical processing, stage two transport, swallowing pharyngeal phase

Question 2

What happens during the second stage of feeding?

Answer 2

Stage one transport. Bolus is gathered at tongue tip and then pushed back towards posterior teeth. Hyoid bone retracts

Question 3

What happens during the third stage of feeding?

Answer 3

Mechanical processing. Solid foods need to be chewed and mixed with saliva before transport and swallowing. Food is chewed with premolars and molars. Moist solid foods need to have liquid removed before transport and swallowing. Soft foods are squashed against hard palate.

Question 4

What happens during the fourth stage of feeding?

Answer 4

Stage two transport. Bolus moved posteriorly towards fauces through ‘squeeze-back’ (tongue retracts). Liquids are held at pillars of fauces through seal. No seal involved with solid foods.

Question 5

What happens during the fifth stage of feeding?

Answer 5

Swallowing pharyngeal phase. Involuntary movement of bolus from pharynx into oesophagus. Epiglottis closes over trachea to prevent food entering the respiratory tract. UOS relaxes to permit bolus entering oesophagus - it then contracts to prevent any backflow.

Question 6

What type of nerve fibres sense a decrease in temperature (cold)?

Answer 6

A delta and C fibre afferent axons

Question 7

What type of nerve fibres sense an increase in temperature (hot)?

Answer 7

C fibre afferent axons

Question 8

What are the different types of muscle fibres? Describe these.

Answer 8

Type I - slow, weak, resilient (fatigue resistant) - used under normal circumstances
Type II - fast, strong, fatigue easily - used under stress

Question 9

What is the origin, insertion and action of the masseter muscle? How would you examine this muscle?

Answer 9

origin = zygomatic arch
insertion = lateral surface of mandible and angle of mandible
action = elevates mandible
Place one finger intra-orally and the other on the cheek (tender in patients who have a clenching habit).

Question 10

What is the origin, insertion and action of the temporalis muscle? How would you examine this muscle?

Answer 10

origin = floor of temporal fossa
insertion = coronoid process and anterior border of ramus
action = elevates and retracts mandible
Palpate its origin by asking patient to clench teeth (tender in bruxist patients)

Question 11

What is the origin, insertion and action of the lateral pterygoid muscle? How would you examine this muscle?

Answer 11

origin = from the lateral surface of the lateral pteryoid plate
insertion = anterior border of condyle (inferior belly) and intra-articular disc (superior belly) via two independent heads
action = protrudes and laterally deviates mandible; inferior head functions with the mandibular depressors during openings
Best examined by recording its response to resisted movement.

Question 12

What is the origin, insertion and action of the medial pterygoid muscle? How would you examine this muscle?

Answer 12

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
NO RELIABLE WAY OF EXAMINING THIS MUSCLE.

Question 13

Name the suprahyoid muscles. What are their function? What muscles act as jaw depressors?

Answer 13

Digastric, mylohyoid, geniohyoid, stylohyoid
Connect hyoid bone with mandible and skull - elevate the hyoid bone and related structures.
When the hyoid bone is fixed, by contraction of the infrahyoids, the starred () muscles act as jaw depressors.

Question 14

Name the infrahyoid muscles. What do these connect to?

Answer 14

sternohyoid, omohyoid, thyrohyoid, sternothyroid

Connect hyoid bone, thyroid cartilage and shoulder girdle.

Question 15

What are the different types of tongue muscles?

Answer 15

intrinsic (alter shape) - longitudinal, vertical, transverse

extrinsic (alter shape, position) - genioglossus, hyoglossus, palatoglossus, styloglossus

Question 16

What are the different movements of the TMJ? Describe these.

Answer 16

Rotation - initial opening, hinge movement
Translation - wider opening, condyle moves forward onto articular eminence, maximum mouth opening; sliding (protrusive or retrusive movements) - during protrusion, both condyles leave their fossae and move forward along the articular eminences - during retrusion, both condyles leave the eminences and move back into fossae

Question 17

Describe the action of the gag reflex. What cranial nerves are involved in the gag reflex?

Answer 17

Stimulus at receptor; sensory afferent; interneuron; motor efferent; motor response
trigeminal nerve (CNV), glossopharyngeal (CNIX), vagus (CNX), accessory (CNXI), hypoglossal (CNXII) - efferent motor response

Question 18

What is the sensory innervation of the tongue?

Answer 18

anterior 2/3 = lingual nerve - general, chorda tympani - special (CNVII)
posterior 1/3 = glossopharyngeal (CNIX)

Question 19

What is dysphagia? How is it caused?

Answer 19

Inability to swallow.

Can be caused by stroke, brain injury, MS, GORD, tumours.

Question 20

What are the different phases of the chewing cycle? Give examples of foods with different chewing cycles.

Answer 20

occlusal phase - intercuspal position
opening phase - lateral pterygoid and gravity depress mandible
closing phase - masseter, medial pterygoid and temporalis elevate mandible back into occlusal phase

A food with a narrow chewing cycle - brittle food e.g. carrot
A food with a broad chewing cycle - tough food e.g. meat
A food with a small chewing cycle -

Question 21

How do dentures affect mastication?

Answer 21

Biting forces are reduced in complete denture wearers
Biting load carried by mucosa of residual ridge
Support area is reduced (mucosa vs PDL)

Question 22

What is dysphasia?

Answer 22

A specific language disorder causing an inability to communicate.

Question 23

What are the different consonant sounds?

Answer 23

Fricatives - escape of air through constriction - f, v, th
Plosives - sudden release after complete stoppage of airflow (stop consonants) - p, b, t, d, k, g
Nasals - air flows through nose - m, n, ng

Question 24

When are the vocal chords open or closed?

Answer 24

Open for breathing

Closed for speaking

Question 25

How can language and speech defects be caused?

Answer 25

Brain - dysphagia
Neuromuscular - lesions
Oral - malocclusions, dentures, cleft palate, tongue, xerostomia

Question 26

What are the three stages of swallowing?

Answer 26

buccal phase (voluntary, squeeze-back mechanism, duration not dependent on food consistency)
pharyngeal phase (involuntary, duration dependent on food consistency)
oesophageal phase (involuntary, peristalsis)