pete smith senior lecturer in oral biology /...

Pete Smith

Senior Lecturer in

Oral Biology / Physiology

1st BDS Teaching Lead

School of Dentistry

www.petesmif.org.uk

Ingestion of a meal

• Mastication

• Salivary glands and salivation

• Deglutition

• Salivary gland pathology

Muscles of Mastication

temporalis

Masseter: arises from the zygomatic process of the maxilla and inserts into the angle and ramus of the mandible

Temporalis: arises from the temporal fossa and inserts onto the coronoid process of the mandible

mandible

hyoid

maxilla

temporal

Muscles for closing the mouth

Muscles of Mastication

temporalis

lateralpterygoid

Digastric: posterior: arises from the mastoid notch; anterior arises from lower border of the mandible. Insert onto the hyoid

Lateral pterygoid: arises from the sphenoid and inserts onto the condyloidprocess of the mandible

Infrahyoid: (4 pairs if muscles) arise from hyoid insert onto clavicle (ish). All of the muscles of

mastication are innervated by the mandibular branch of the trigeminal nerve

mandible

hyoid

maxilla

temporal

Muscles for opening the mouth

Control of Mastication

• Voluntary

• Reflexes: Jaw opening reflex; Jaw-jerk reflex

• Brain stem pattern generator

• Fine tuning via sensory feedback through periodontal ligaments and proprioceptors

• A change in occlusion (e.g. following dentistry) will alter the chewing pattern.

• There are 3 main movements of mastication

Movements of Mastication

The temperomandibular joint (TMJ) allows three movements of mastication:

open/close; protrusion/retraction; lateral

Salivaryglands

submandibularsublingual

parotid

Salivation

SalivaryNuclei

mastication

+VII

IX

tastesmell

anticipation

-

fear

Superior (pons)

Inferior (medulla)

• Tooth maintenance

• Lubrication

• Antibacterial/antifungal

• Digestive

Functions of Saliva

: salivary amylase; lingual lipase

: allows speech, mastication and deglutition

rampant caries

candida infection

• Tooth maintenance

Functions of Saliva

: dilution, clearance and buffering

0 20 40

Time (seconds)

Pla

qu

e p

H

5

5.5

6

6.5

7

Stephan Curve

Critical pH

teeth demineralise

rampant caries

• Lubrication

Functions of Saliva

: salivary glycoproteins are sticky

• Antibacterial/antifungal

Functions of Saliva

: protective barrier; IgA; lysozyme etc.

Saliva and Oral Health

4th Edition

ISBN: 9780956566836

Paperback: £25.00

Saliva and Oral Health

3rd Edition

Many copies available in the library

Much more detail available in:

Salivary Secretion

Parotid

submandibular

sublingual

serous

mucous

mixed

All salivary glands secrete both protein and fluid.The constituency of saliva is determined by the nature of the secreted protein

minor glandsmucous

myoepithelia cell

Striated duct

Excretory duct

Mucous acinus

Serous acinus

Intercalated duct

Serous demilune

endoplasmic reticulum

nucleus

secretory vesicles

apical or lumenal side

basolateral or blood side

noradrenalin

fluidprotein

cyclic

adenosinemonophosphate

cAMP Ca2+

acetylcholine

sympathetic nervous system parasympathetic nervous system

Stimulus-

Secretion

Coupling

b adrenergic receptor

G-protein

adenylate cyclase

CHOH CH NH. .2 2

OH

OH noradrenaline

OH

C

PO4

NH2

cyclic AMP

Protein

Secretion

cAMP stimulates

gene transcription,

glycosylation and

formation of

secretory vesicles

and exocytosis

RR

Polymeric immunoglobulin receptor

PIgR

R

IgA

Transcellular translocation of serum IgA

M3 muscarinic receptor

G-protein

phospholipase C

acetylcholine

inositol 1,4,5 trisphosphate

IP3

N CH CH O CO CH. . . . .2 2 3

CH3

CH3

CH3

Fluid

Secretion

Na+Cl-

K+N CH CH O CO CH. . . . .

2 2 3

CH3

CH3

CH3

Ca2+ release

osm

otic

gra

die

nt

NaCl

receptor

activationIP3

increased

[Ca2+]i

ion channel

activation

fluid & electrolyte

secretion

Deglutition

• Oral/buccal: voluntary: the bolus is pushed to the back of the mouth by the tongue. The teeth are brought together. The soft palate elevates to close the nasal cavity. The larynx rises to close the airways (inspiration is inhibited)

• Pharyngeal: involuntary (reflex): cricopharyngeal sphincter relaxes to open the oesophagus. The epiglottis steers the bolus over the trachea and the peristalsis starts

• Oesophageal: peristalsis; all of the above reverse….

: an autoimmune condition that causes salivary gland dysfunction and atrophy

• What causes xerostomia?

• Drugs

• Disease• Sjogren’s syndrome

Salivary gland pathology

rampant caries

www.petesmif.org.uk

Much more detail available via: