Oral preparatory phase

Question 1

what happens in the oral preparatory phase?

Answer 1

Food:

• enters the oral cavity
• is sealed within the oral cavity
• is ground up and mixed with saliva to form a bolus

This phase is under voluntary control, but can be performed automatically

Question 2

anterior and lateral borders of the oral cavity

Answer 2

the alveolar process of the maxilla and the upper teeth superiorly, the mandible and the lower teeth inferiorly

Question 3

Facial muscles - which are used, and what CN are they innervated by?

Answer 3

Obicularis oris and risorius - close and tense the lips

Buccinator - maintains tension in the cheeks

Innervated by the facial nerve (CNVII)

Question 4

What is dental occlusion, and what can problems with dental occlusion cause?

Answer 4

The way the upper and lower teeth meet when the jaws bite together

Problems can cause difficulty with biting and chewing food (could be caused by poorly fitting dentures, overbite, underbite, crossbite, open bite)

Question 5

The TMJ: what is it and what movement does it enable?

Answer 5

The temporomandibular joint (synovial joint between the condylar process of the mandible and the mandibular fossa of the temporal bone

Rotation of the condylar process in the mandibular fossa (lower joint compartment) causes the mouth to open and close

Gliding movements of the mandibular condyle (upper joint compartment) causes the jaw to protrude and retract

Lateral movement of lower jaw relative to upper jaw enables chewing and grinding

Question 6

Masseter

Answer 6

Masseter: elevates and protrudes mandible (closes mouth)

Question 7

Which muscles close the mouth?

Answer 7

Masseter (up and forward), temporalis (up and back) and medial pterygoid (up and forward)

Question 8

Key constituents of saliva

Answer 8

Water (99.5%)
Electrolytes (salts)
Digestive enzmes (e.g. amylase)
Antimicrobial enzymes that kill bacteria

Question 9

Key functions of saliva

Answer 9

• moistening consistency of food to aid bolus formation and transit
• lubrication of oral mucosa to prevent damage
• initiating digestion of food components
• providing liquid medium to transport food molecules to taste receptors
• maintenace of oral hygiene

Question 10

Intrinsic muscles of the tongue - vertical, transverse and longitudinal (superiro and inferior)

Answer 10

Vertical: flatten and widen tongue
Transverse: elongate and narrow tongue
Superior longitudinal: tip of tongue upwards
Inferior longitudinal: tip of tongue downwards

Question 11

Extrinsic muscles of the tongue and innervation

Answer 11

palatoglossus, styloglossus, hyoglossus, genioglossus

All inervated by hypoglossal nerve except palatoglossus which is innervated by the vagus nerve

Question 12

palatoglossus

Answer 12

elevates posterior part of tongue and depresses soft palate

Question 13

styloglossus

Answer 13

elevates and retracts tongue

Question 14

hyoglossus

Answer 14

depresses and retracts tongue

Question 15

Genioglossus

Answer 15

protrudes the tongue

Question 16

What does the tongue do in the oral preparatory phase?

Answer 16

moves the food around the mouth during mastication, e.g.

- directing between grinding surface of teeth, clearing ressidue from buccal cavity and around teeth

Question 17

roof of the oral cavity

Answer 17

hard and soft palate, uvula

Question 18

floor of the oral cavity

Answer 18

some of they suprahyoid muscles, largely occupied by tongue

Question 19

posterior boundary of the oral cavity

Answer 19

the fauces (arched folds of tissue at the anterior end of the oropharynx)

Question 20

Temporalis

Answer 20

anterior fibres elevate the mandible, posterior fibres retract the mandible (closes the mouth)

Question 21

Medial pterygoid

Answer 21

bilateral contraction elevates and protrudes the mandible (closes the mouth)

unilateral contraction of medial and lateral pterygoid moves the mandible sideways for chewing

Question 22

Lateral pterygoid

Answer 22

Lateral pterygoid: bilateral contraction depresses and protrudes the mandible (opens the mouth)

unilateral contraction of medial and lateral pterygoid moves the mandible sideways for chewing