Teeth:

The hardest, white outer part of the tooth.

Enamel is mostly made of calcium phosphate, a rock-hard

mineral.

Teeth:

A layer underlying the enamel. Dentin is made of

living cells, which secrete a hard mineral substance.

Teeth:

The softer, living inner structure of teeth, Blood

vessels and nerves run through the pulp of the teeth.

Intrinsic Muscles

Intrinsic Muscles

it shortens the tongue and makes the

dorsum of the tongue concave

Intrinsic Muscles

It also shortens the tongue but it

makes the dorsum of the tongue convex

Intrinsic Muscles

Function: to make tongue narrow and elongated

Intrinsic Muscles

Function: to make tongue narrow and elongated

Extrinsic Muscle

Extrinsic Muscle

Function: to protrude the tongue out by pulling

the posterior part forward (or pag nilabas ang

dila sa mouth)

Extrinsic Muscle

Function: it depresses the tongue

Extrinsic Muscle

Function: pulls the tongue upward and backward

Extrinsic Muscle

Function: brings the palatoglossus arches

together and it shut-offs the oral cavity from the

oral pharynx.

Mechanical process of chewing

Initial chewing action

the incisal edge of incisors is the working edge.

Characteristics:

a) Knife-like edge of the incisors

b) Monorooted condition which is sufficient for their simple function

c) Incisors are supported by the intermaxillary sutures & the symphysismenti

d) Lips are in contact & there is the presence of oral seal

e) Teeth comes in full contact

involves shearing movement of the mandible.

- (Shear - to cut through due to sliding action)

- Characteristics:

a. Includes cuspids & bicuspids.

b. Presence of a more inclined plane or more surface contact.

c. Working side is where the food is & the other side will be the balancing side.

- Working site of the occlusion

- No food – balancing side/ non-functioning occlusion

- complete trituration of the food & this involves

all occlusal surfaces.

Characteristics:

a. Normal oral seal produced by the upper & lower lip.

b. Normal occlusion is present.

c. Normal antero-posterior relationship of the maxilla & mandible.

d. Presence of symmetrical phase.

e. Tongue is kept within the oral cavity.

f. There is harmonious relationship between the cranial & facial structure.

g. Mastication is soundless.

- Separation of teeth

- Condyles move forward and Downward

- During opening, the jaw is about 10-15 mm

- Muscles responsible: mylohyoid, Digastric, inferior lateral

pterygoid

- Rapid jaw closing phase

- Occlusal surfaces are brought together.

- Accomplished by the masseter, internal pterygoid &

temporalis muscle.

- Muscle undergo isotonic contraction or relaxation

- Slow jaw closing phase

- Tooth contact phase

- Power phase

- Food particles are crushed between the occlusal surfaces

- Gradual change to isometric contraction when teeth are in

contact & there is an object between them.

muscle contraction that develops tension

without appreciable shortening or change in distance between its

origin & insertion. Clenching of already occluded jaws is an example

if there is pressure and change in the muscles example flexion of bicep

3 Phases of deglutition

Phases of Deglutition

- Total swallow time from oral cavity to stomach is no more than 20

seconds the process begins with contractions of the tongue and

striated muscles of mastication. In the oral phase, a formed bolus is

positioned in the middle of the tongue. The bolus is then pressed

firmly against the tonsillar pillars, triggering the pharyngeal phase.

Characteristics:

A. Anterior portion of tongue is retracted

B. Hyoid bone is elevated

C. Mastication stops

D. Respiration reflex stops

E. Back portion of tongue is elevated & retracted against the

palate

- The pharyngeal phase of swallowing is the shortest but is

the most complex.

- In this phase the soft palate elevates closing off the

nasopharynx and preventing nasopharyngeal regurgitation

- Then the pharyngeal phase begins, other activities such as

chewing, breathing, coughing and vomiting are

concomitantly inhibited

- Closure of the nasopharynx

- The bolus is propelled about 25 cm from the

cricopharyngeus through the thoracic esophagus via

peristaltic contractions

- The bolus is propelled downwards at a rate of 3–5 cm/s.

- The lower esophageal sphincter relaxes and the bolus

moves into the gastric cardia.

What are the 2 important reflex action: