PHYSIOLOGY STOMATOGNATHIC SYSTEM

PART-5
CONTENTS

 INTRODUCTION

 FUNCTIONAL ANATOMY OF ORAL CAVITY

 SALIVARY GLANDS

 PHYSIOLOGY OF SALIVA SECRETION

 MASTICATORY SYSTEM

 PAIN PHYSIOLOGY

 DEGLUTITION

 SPEECH

 CONCLUSION

 REFERENCES

INTRODUCTION

PHYSIOLOGY

Concerned with the functioning of organism and the processes , function of all or part of an organism

STOMATOGNATHIC SYSTEM

Structures of the mouth and jaws considered collectively as they subserve the function of mastication ,
deglutition ,respiration and speech

FUNCTIONAL ANATOMY OF ORAL CAVITY

Oral cavity also known as buccal cavity. Oral cavity opens anteriorly to the exterior through the lips
and posteriorly through fauces into PHARYNX.digestive juice present in the mouth is saliva which is
secreted by salivary glands

FUNCTIONS OF ORAL CAVITY

1. Ingestion of food materials

2. Chewing of food and mixing with saliva

3. Appreciation of taste of the food

5. Speech

6. Smiling and other expressions

SALIVARY GLANDS

 SALIVA

Saliva is the clear mucoserous secretion formed mainly in salivary glands and has lubricative,
cleansing & anti microbial, excretory and digestive functions.

Oral fluid also known as whole saliva or total saliva is composed primarily of saliva secreted by
major and minor salivary glands.

Classification of salivary glands

Based on size and location

MAJOR SALIVARY GLAND MINOR SALIVARY GLANDS

Parotid Labial & buccal glands

Submandibular Palatine glands

Sublingual Glossopalatine glands

Anterior lingual/Glands

of

Blandin & Nuhn

Posterior lingual

Glands of Von Ebner

BASED ON THE HISTOCHEMICAL NATURE OF THE SECRETORY PRODUCT

MUCOUS

Labial & buccal glands

Palatine

Anterior lingual

SEROUS

Parotid

Glands of von Ebner

MIXED

Submandibular (serous predominant)

Sublingual (mucous predominant)

Based on the duct system

SIMPLE Minor Salivary Glands

COMPOUND Submandibular

Parotid

Sublingual

STRUCTURE OF THE SALIVARY GLAND

The working parts of the salivary glandular tissue

consists of secretory end pieces (acini),

myoepithelial cells and the branched ductal

system.

Serous glands – roughly spherical

Mucous glands – tubular configuration

DUCTAL SYSTEM :

1.Intercalated duct

2.Striated duct

3.Excretory duct

NERVE SUPPLY OF SALIVARY GLANDS

-Salivary glands are purely under nervous control .

-Nerve supply is from the sympathetic and parasympathetic branches of autonomic nervous
system.

-Stimulation of sympathetic supply – release of amylase and vasoconstrictor

-Parasympathetic nerves are secretomotor

FORMATION OF SALIVA
TWO STAGE HYPOTHESIS
OF SALIVA FORMATION
PROPERTIES OF SALIVA

• VOLUME-1000-1500 ML/DAYPH

• PH-6.35-6.85

• TONICITY-SALIVA IS HYPOTONIC TO PLASMA

• SPECIFIC GRAVITY-1.002-1.12

Applied Aspects

The main causes of hyposalivation are

1) Ageing

2) Iatrogenic

Drugs

Irradiation

1) Disease

• Salivary gland disease

Salivary aplasia (agenesis)

Infections

1) Dehydration

2) Psychogenic (anxiety, stress)

SALIVARY GLAND HYPERFUNCTION

Drugs

-cevimiline

-physostigmine

-pilocarpine

Other conditions

-parkinson’s disease

-heavy metal poisoning

Composition of saliva
 PHYSIOLOGY OF GUSTATION
TRANSMISSION OF TASTE SIGNALS TO CN

TASTE PAPILLAE
TASTE BUDS

 Taste buds are group of 30-100 individual elongated neuroepithelial cells

 Which are 50-60 microns in height and 30-70 microns in width which are embedded in
epithelium

MECHANISM OF STIMULATION OF TASTE BUD

Stimulating substance or tastant

Binding to microvilli ( protein receptor molecule)

Stimulates exocytosis and release of neurotransmitter from vesicles

Opening of ion channels and entry of Na ions

Depolarisation of cell membrane

PRIMARY SENSES OF TASTE

SALIVA-TASTE INTERACTION

Gustatory function at the peripheral level requires 3 factors-

 A molecule that elicits taste

 A taste receptor cell

 An aqueous environment provided by saliva

Saliva contributes the tasting ability by-

 First as a solvent of food

 Second as a carrier of taste eliciting molecules

 Third through its composition

Hence when the salivary output is affected adversely , taste function can concomitantly affected

TASTE DYSFUNCTION

Loss or impairment of taste can occur in degrees

NORMOGEUSIA

HYPOGEUSIA

DYSGEUSIA
 ALIAGEUSIA

PHANTOGEUSIA

AGEUSIA

APPLIED ASPECTS
 MASTICATORY SYSTEM

Masticatory system includes

-Hard tissue components

-Soft tissue components

STRUCTURE OF SKELETAL MUSCLE

MUSCLE FIBER

The end of the muscle fiber fuses with a tendon fiber

Tendon fibers in turn collect into bundles to form the muscle tendon that inserts into the bone

Muscle fiber contains several hundred to several thousand myofibrils

Each myofibril in turn lying side by side, about 1500 myosin filaments and 3000 actin filaments, which
are large polymerized protein molecules that are responsible for muscle contraction.

CLASSIFICATION OF MUSCLE FIBRES

Muscle fibers can be characterized by type according to the amount myoglobin

 FAST MUSLE FIBERS OR TYPE 2 MUSLE FIBERS OR PALE MUSCLES

Based on functional and histological appearance

 TYPE S or Slow , fatigue resistant fibres

 TYPE FR or fatigue resistant fibres

 TYPE FF or fast fatigable fibres

TYPES OF MUSCLE CONTRACTION

 ISOTONIC CONTRACTION

 ISOMETRIC CONTRACTION

MUSCLES OF MASTICATION

FUNCTIONS OF MASSETER MUSCLE

As fibers of the masseter contract, the mandible is elevated and the teeth are brought into contact.

Its superficial portion may also aid in protruding the mandible.

When the mandible is protruded and biting force is applied, the fibers of the deep portion stabilize the
condyle against the articular eminence.

FUNCTION OF TEMPORALIS MUSCLE

When the temporal muscle contracts, it elevates the mandible and the teeth are brought into contact.

When the anterior portion contracts, the mandible is raised vertically

Contraction of the middle portion will elevate and retrude the mandible.

Posterior fibers below the root of the zygomatic process contraction will cause elevation and slight
retrusion.

FUNCTION OF MEDIAL PTERYGOID

Along with the masseter, it forms a muscular sling that supports the mandible at the mandibular
angle.

When its fibers contract, the mandible is elevated and the teeth are brought into contact.

This muscle is also active in protruding the mandible

Unilateral contraction will bring about a mediotrusive movement of the mandible.

FUNCTIONS OF INFERIOR LATERAL PTERYGOID

When the right and left inferior lateral pterygoids contracts simultaneously

condyles are pulled down the articular eminences and the mandible is protruded.

Unilateral contraction creates a mediotrusive movement of that condyle and causes a lateral movement
of the mandible to the opposite side.

When this muscle functions with the mandibular depressors,the mandible is lowered and the condyles
glide forward and downward on the articular eminence

Functions of superior lateral pterygoid

Although the inferior lateral pterygoid is active during opening, the superior remains inactive .Becoming
active only in conjunction with the elevator muscles.

The superior lateral pterygoid is especially active during the power stroke and when the teeth are held
together.

The powerstroke refers to movements that involve closure of the mandible against resistance, such as in
chewing or clenching the teeth together.

DIGASTRIC MUSCLE

FUNCTION-elevates the hyoid and depresses mandible

Mylohyoid muscle

FUNCTION-elevates hyoid and floor of the mouth

and Depresses the mandible

FUNCTION OF BUCCINATOR MUSCLE

 Purpose is to pull back the angle of the mouth and to flatten the cheek area –which aids in
holding the cheek during chewing

 This action causes the muscle to push back the food on the occlusal surface of posterior teeth

 It aids whistling and smiling

 In neonates it is used to suckle

CONTROL OF MANDIBULAR REST POSITION

HEAD IS MOVING VIGOROUSLY UP AND DOWN DURING RUNNING AND JUMPING STRETCH
REFLEXES

• CHEWING CYCLE

• Preparatory phase

• Food contact phase

• Food crushing phase

• Tooth contact phase

MECHANISMS THAT MODULATE JAW MUSCLE ACTIVITY DURING CHEWING

 MUSCLE SPINDLE RECEPTORS

 MECHANORECEPTORS

BITE FORCES DURING NORMAL MASTICATION

 Maximum biting force is upto 350 N

 When chewing western diets,jaw closing muscles exert only 30-40% of their maximum force

 The maximum bite force of who have lost all their natural is decreased by 50% ,even when they
wear well fitting dentures

MASTICATORY MUSCLE VS NORMAL MUSCLES

The extraordinary force exerted by masticatory muscles is due to-

 fiber composition

 Biomechanics

 Most muscles act via long tendons and insert onto bones - poor mechanical advantage

Eg-elbows ,knees

 Where jaw muscles act directly across the temporomandibular joint - good mechanical
advantage and with no need of tendon

APPLIED ASPECTS

MUSCLE PATHOLOGY

MUSCULAR DYSTROPHY –
DUCHENNE’S MUSCULAR DYSTROPHY

-Becker muscular dystrophy

MYOSITIS - inflammation of the muscle that results from local causes such as traumatic injuries,muscular
strain,orodental infections

Myofascial pain syndrome - it is a pain disorder in which unilateral pain is referred from the trigger
points in myofascial stuctures to the muscles of the head and neck

Causes-

sudden mouth opening

Phyisiological stress

Bad posture

Muscular tension

Bruxism

NEUROMUSCULAR JUNCTION DISEASES

-MYASTHENIA GRAVIS

-LAMBERT-EATON SYNDROME

DEGLUTITION

DEGLUTITION

-The process or act of swallowing which is carried by stomatognathic system

Phases of deglutition –

 INFANTILE SWALLOW

 MATURATION SWALLOW

 Oral preparatory phase

 Pharyngeal phase

 Oesophageal phase

 INFANTILE SWALLOW
  Swallowing pattern is purely reflex in nature in newborn(involuntary)

 The ability to feed from the breast is present in the newborn child by negative pressure

 The milk is directed continuously to the pharynx by an autonomous peristalitic movement of

During swallowing-

the entrance to infant larynx is elevated

Then epiglottis placed behind the soft palate

Which is then possitioned in the vallecular space just infront of the epiglottis

Functionally continues tube from the nose through the larynx to the bronchi

This enables uninterrupted breathing even during swallowing

DISTINGUISING FEATURES BETWEEN MATURE AND INFANTILE SWALLOW

 The jaws are apart and the tongue is placed between the upper and lower gum pads

 The mandible is stabilised by the contraction of the muscles of facial expression(innervated by

 The swallow is guided and to large extent controlled by the sensory interchange between lips
and tongue

Mature swallow

Oral preparatory phase

 It is voluntary stage
 The anterior of the tongue is raised and pressed against the hard palate by superior
longitudinal and transverse muscles
 The movement takesplace from anterior to posterior side
 This pushes the food bolus into the posterior part
 The soft palate closes down on to the back of the tongue and helps to form bolus
 Next the hyoid bone is moved upwards and forwards by the suprahyoid muscles
 The posterior part is supported by styloglossi
The palatoglossal arches are approximated by palatoglossi

This pushes the bolus through the oropharyngeal isthmus to the oropharynx

Now next stage begins

PHARYNGEAL PHASE
 It is an involuntary stage

During this stage food is pushed from the oropharynx to the lower part of the laryngopharynx

Nasopharyngeal isthmus is closed by the soft palate by levator veli palatani and tenser veli palatani

This prevents the food bolus from entering the nose

PHARYNGEAL MUSCLE CONTRACTION:

 Soft palate is pulled upward and prevents the reflux of food to nasal cavity

 Palatopharyngeal folds are pulled medially to approximate each other – form a saggital slit

 Vocal cords are approximated

 Larynx is pulled upward & anterior by neck muscles

 Epiglottis swing backward over the opening of larynx

Upward movement of larynx & enlargement the opening of esophagus

Upper 3-4cm of esophagus relaxes

Muscular wall of pharynx contracts to push the food downward (propulsive contraction)

OESOPHAGEAL PHASE

This phage commences as soon as the food passes the cricopharyngeal sphincter

Peristalitic activity of the oesophageal walls occur to pass the food into the stomach

Tongue and palate return to their original position to start the next cycle

ESOPHAGEAL STAGE OF SWALLOWING

 Conducts food rapidly to the stomach

 Two types of peristaltic movements:

1° peristalsis:

– continuation of a peristaltic wave

– begins in pharynx & spreads into esophagus

– passes in 8-10 sec

2° peristaltic waves:
– results from the distention of esophagus

– begins if the 1° wave failed to push the food down

Esophageal reflux can be prevented by

 Gastro-esophageal sphincter

 Valve-like mechanism: short portion of the esophagus that extends beneath the diaphragm
before opening into stomach

Applied aspects

BULIMIA NERVOSA

ANOREXIA NERVOSA

GASTRO-OESOPHAGEAL REFLEX DISEASE

PLUMMER-VINSON SYNDROME

Speech vs language

LANGUAGE

Language comprises the central function associated with Processing of linguistic information in the brain

SPEECH AND HEARING

It denotes the peripheral processes that are needed to produce spoken language and to receive spoken
utterances

SLEEP APNEA

Central sleep apnea - which occurs when the brain fails to send important signals to the breathing
muscles

Obstructive sleep apnea - which occurs when air cannot flow through the nose or mouth even though
the body is still trying to breathe.

Obstructive sleep apnea is far more prevalent and easily treatable by the dentist.

This disorder causes significant morbidity, particularly in terms of daytime functioning and its impact on
quality of life.

Upper airway space

 Clinical oral physiology- timothy et al

 Clinical oral sciences– malcolm harris, edgar and meghji

 Human anatomy volume -3 b.d chaurasia th edition

 Atlas of anatomy-netter 3rd edition

 Grays anatomy

 Human physiology-a.k.jain

 GUYTON-PHYSIOLOGY- 11 TH EDITION

 OKESON - MANAGEMENT OF TEMPOROMANDIBULAR JOINT DISORDERS AND OCCLUSION -

 Salivary diagnostics , DAVID T.WONG