TMJ /certified fixed orthodontic courses by Indian dental academy

TEMPOROMANDIBULAR JOINT

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INDIAN DENTAL ACADEMY
Leader in continuing dental education


CONTENTS
EVOLUTION
DEVELOPMENT
ANATOMY
PHYSIOLOGY
BIOMECHANICS

BICONDYLAR GINGLIMOARTHROIDAL COMPOUND JOINT

EVOLUTION OF TMJ


THE LIVING VERTEBRATES
CLASS

EXAMPLE

Agnatha

Lampreys

Condrichthyes

Sharks

Osteichthyes

Bony fishes

Amphibia

Frogs, toads

Reptilia

Snakes, turtles, lizards

Aves

Birds

MAMMALIA
Protheria

Platypus

Metatheria

Marsupials

Eutheria

Placental mammals


SCHOOLS OF THOUGHT
Morphological concept

Suspension and suction

Support for ventilation

Genetics

AGNATHA
Vertebrates without jaws
Gill slits- Filtering and feeding
Epiceratobranchial joint in
mordern sharks
Oral opening


filtering

GNATHOSOMES
Ist & IInd gilled arches- Brain
IIIrd & IVth gilled arches- Prehension
CEPHALIZATION
Skin over the edges- Teeth
Simple hinge joint- Quadrate-Articular
Eudiarthroidial joint- True bony fishes

JAW AND THE CRANIUM
A.

Gill Slits

B.

Autostyly

D.

Modified autostyly

C.

Amphistyly

E & F. Hyostyly
G.

Holostyly

AMPHIBIA
Jaws – cartilagenous core with
blanket of dermal bones
Joints- Quadrate-Articular
eudiarthroidial


REPTILIA
Increase in the dentary bone
in backward direction
Increase in muscle size and
their mechanical advantage
Dentary-Squamosal joint replaces
Quadrate-Articular joint
Temporalis- orgin & insertion
Streptostylic suspension www.indiandentalacademy.com

SEQUENCE OF CHANGES
Availability of particular diet
Variations in tooth form
Replacement of the old joint
Adaptation of the musculature
Response of the bone
Coordination activity of the joints

Why there was a need of formation of
new joint
Prey size
Muscle force , mass and direction of muscle pull
Complex pattern of muscle activity
Rigid lower jaw
Greater range of movements


MAMMALIA
EUTHERIA

CARNIVORE

HERBIVORE

RODENT


HUMANS

FUNCTIONAL POWER STROKES
PREHENSION

COMMUNITION
CRUSHING

TEARING
CARNIVORE HERBIVORE

CUTTING

GNAWING GRINDING SLICING

CARNIVORES
Projecting jaws used for grabbing
prey
Long lower jaws with no ramus
Large coronoid process and
large temporalis
Horizontally expanded temporal
fossa
Short zygomatic area

CONDYLE

Firmly fitted joint


HERBIVORES
Long jaws with long cheek teeth
and no canines
Cheek teeth are set well posterior
Jaw joint is fitted for wide, gliding and
horizontal movements
Small coronoid process
decreased temporal fossa
Enormously lengthened masseter
orgin

Lateral movements of the joint


RODENTS
Large sharp edged chisel shaped
incisor teeth
Long gap between incisors and
cheek teeth
Antero-posteriorly directed glenoid
groove
Less lateral movements of joint


HOMINIDS
Upright posture
Bipedal locomotion-Increased
manual dexterity
Shrinkage and retraction of jaws
Change of diet- Omnivores
Increase in brain size

TMJ IN PRIMATES
Unspecialized
Specialized
Universal


D

THE MUSCLES

L

M

inspiratoy
gills
V

expiratoy

III ORDER LEVER
R

F

E


Reptile

Early mammal

Mammal

Shark

Lobe finned fish

Primitive amphibian

Primitive reptile

Primitive marsupial


Primitive primate
Man

Chimpanzee


CONDYLAR CARTILAGE
Membranous bone with periosteum
Pressure on the condyle
Localized ischemic changes
Undifferentiated mesenchymal cells
Chondroblasts proliferation
Cartilage formation

INTERARTICULAR DISK
No separate cartilage
Enlargement of the dentary
Muscle from the pterygoid region

Attachment to the new joint


EVOLUTION & MOLECULAR
BIOLOGY
Homeobox genes (HOX)
Neural crest cells – mid brain
Hox-free default in mandibular arch
Myosin heavy chain (MYH)


Neural crest cells

DEVELOPMENT OF TMJ


MECKELS CARTILAGE
Cartilage of the first arch
Extent of the cartilage


PRIMARY JOINT
6th week- formation
8th week- supports the mandible
Dorsal end is continuous with
the developing ear ossicles
16th week- Ossicles undergo
endochondral ossification
10 WEEKS

CONDYLE
9th week- start
10-11 weeks- chondrifies
12th week- fuses with ramus
20 weeks- completion


9-10 WEEKS

12 WEEKS ONWARDS
14 weeks
11 WEEKS
12 WEEKS

22 WEEKS
16 WEEKS
AT BIRTH

CARTILAGES

PRIMARY
SECONDARY

Differences

….koski et al 1968

CHARACTER

CONDYLAR
CARTILAGE

EPIPHYSEAL
CARTILAGE

GROWTH

APPOSITIONAL

INTERSTITIAL

INTERMIDIATE
LAYER

UNDIFFRENTIATED

CARTILAGE CELLS

ORGANIZATION OF
CELLS

RANDOM

LINEAR

MINERALIZATION

HYPERTROPHIC
ZONE

DEGENERATIVE
ZONE

INTRINSIC GROWTH
POTENTIAL

ABSENT

PRESENT

RESPONSE TO MECH. MORE
STIMULATION

LESS

SPONGIOSA

PRESENT

ABSENT

According to BAUME:
Growth Center:
Is a site of endochondral ossification with
tissue separating force,contributing to the
increase of skeletal mass.
Growth Site:
Regions of Periosteal or suture bone
formation and modeling resorption adaptive
to environmental influences.


GROWTH OF THE CONDYLE
Articular surface
Proliferative zone

Cartilage

Subchondral bone

ENDOCHONDRAL GROWTH OF CONDYLE
Forces are compressive in nature
Direction of growth
Periosteum adapts itself mainly
to tensile forces
Cartilage
Endochondral bone tissue
cortices

CLINICAL CONSIDERATIONS
7-11 weeks morphogenesis- teratogens
Regional adaptive growth
Arrangement of the prechondroblast cells


HENCE Condylar cartilage is –
SECONDARY IN EVOLUTION
SECONDARY IN DEVELOPMENT
SECONDARY IN GROWTH


GLENOID FOSSA
7-8 weeks - Develops earlier than the condyle
10th week- ossification
22 weeks- medial and lateral walls
Shape of the fossa


ARTICULAR CAPSULE
9-11 Weeks- first appearance
17th Week- differentiation
26th Week- completion


ARTICULAR EMINENCE
7TH month- Formation of the trabeculae
8-9 months- Completion


SUMMARY
TMJ is one of the last synovial joints to develop
Develops from two blastema
It has an fibro cartilage covering
Condyle is a primarily a growth site


ANATOMY OF THE TMJ


JOINTS
FIBROUS

CARTILAGENOUS

SYNOVIAL

SYNARTHROSES

SYMPHYSES

SYNDESMOSES

SYNCHONDROSES

GOMPHOSES


SYNOVIAL JOINT
Gross anatomy
Hyaline cartilage
Low friction
Weeping lubrication


THE CONDYLE
Oval shaped structure
15-20 mm M-L & 8-10 mm A-P
Poles of the condyle
Long axis


GLENOID FOSSA
Squamous portion of the temporal bone
23 mm M-L & 15 mm A-P
NOT a stress bearing portion
RELATIONS


ARTICULAR EMINENTIA
Anatomy
Slopes- Anterior & Posterior
Functional area


ARTICULAR DISK
Zones of the disk
Surfaces
Relations & attachments
Significance of fibro cartilage
Functions


RETRODISCAL TISSUE
SUPERIOR

INFERIOR


FIBROUS CAPSULE
Attachments
Layers of the capsule
Functions

capsule


CAPSULE
fossa

capsule
condyle


LIGAMENTS
EXTRINSIC

INTRINSIC
Temporomandibular lig

Sphenomandibular lig

Collateral lig

Stylomandibular lig
Pterygomandibular
raphe


Contra lateral TM
lig

TEMPOROMANDIBULAR
LIGAMENT
Two layers
Functions


FUNCTION OF TM LIGAMENT


COLLATERAL LIGAMENT

SPHENOMANDIBULAR LIGAMENT
ORGIN
INSERTION
RELATIONS
FUNCTIONS

STYLOMANDIBULAR LIGAMENT

BLOOD SUPPLY


NERVE SUPPLY


HISTOLOGY

MACROSCOPIC


ARTICULAR EMINENCE GLENOID FOSSA

MICROROSOPIC


CONDYLE

SYNOVIAL MEMBRANE
Vascular connective tissue
Retrodiscal tissues
Type A cells- macrophages
Type-B cells- synovial fluid (80%)
LUBRICATION
NUTRITION

RADIOGRAPHIC ANATOMY
TRANSCRANIAL
PANORAMIC


ARTHROGRAPHY


CT IMAGING


MRI IMAGING


PHYSIOLOGY OF TMJ


NEUROANATOMY
REFLEXES OF THE JOINT
PSYCHOLOGICAL ASPECTS


NEUROANATOMY
SENSORY INERVATION
Main nerve supply- Auriculotemporal nerve- Posterior & lateral parts
of the capsule
It has the richest innervations
Massetric & Deep temporal – medial parts of the capsule
Center of the disk and the articulating surfaces are not innervated


RECEPTOR INNERVATION OF
TMJ
FOUR TYPES
RUFFINI
GOLGI-TENDON
VATER PACINI CORPUSCLES
FREE NERVE ENDINGS

ANATOMICAL
DESIGNATION

FUNCTIONAL
DESIGNATION

REFLEX ROLE

LOCATION

RUFFINI
ENDING

Static
mechanoreceptor

Posture

Post & posterioro
-lateral aspects of
capsule

VATER-PACINI
CORPUSCLE

Dynamic
mechanoreceptor

Movement
accelerator

TM ligament

GOLGI TENDON

Static
mechanoreceptor

Protection of the
ligament

TM ligament

FREE NERVE
ENDING

Pain receptor

Protection of the
joint

Distributed
throughout the
capsule


CENTRAL PROJECTION


MOTOR INNERVATION
REFLEXES OF TMJ ORGIN

Mandibular
Inhibition in masserteric
closing
discharge
TONUS
facilitation

Opening of
mandible


JAW CLOSING REFLEX
The stretch reflex of jaw closers
When the jaw is tapped muscle spindles of elevators are excited
The A.P generated travel to the mesencephalic nucleus
Travels to motor nucleus
Extra fusal fibers of the elevator muscle



FUNCTION- Maintenance of the jaw against gravity and the
inertial loading



MONOSYNAPTIC


JAW OPENING REFLEX
The flexor reflex of the jaw closers
Reflex is activated biting into hard objects
A.P is carried to the spinal nucleus
Interneurons synapse with motor nucleus
Excitation of the depressors

FUNCTION- protection of the hard and soft tissues
POLYSYNAPTIC


JAW UNLOADING REFLEX
Sudden breakage of the food item
Sudden closing of the jaw
Spindles are unloaded
Elevators are inhibited
Occlusion is prevented

REFLEXES PROTECTING THE TMJ
These reflexes ONLY operate to restrict EXTREME opening
movements
Maximal opening could be increased with anesthesia
Attenuation of discharge on the contralateral muscles
TMJ has no receptors that can monitor loading of the joint


REFLEXES PROTECTING THE
TEETH
Normal postion of the
mandible
Balancing interference
Position of the
mandible
Position of the
mandible

Balancing interference

Normal
closing
Mandibular deviation


TMJ AND THE TONGUE
0 DEG- no change in genioglossus muscle
21 < DEG- increased activity is seen
Infiltration of the anesthetic abolished the reflex
Associated with the receptors monitoring the adequeacy of the
ventilation


PSYCHOLOGICAL ASPECTS OF
THE INERVATIONS
MANDIBULAR POSITION SENSE
Duplication of the mandibular movement
SIZE THRESHOLD- .01 MM of objects


SUMMARY
Auriculotemporal nerve- lateral & posteriorly
Jaw muscle activity probably affects the sensitivity of receptors
Its sensitivity is increased by inflammation and elevated
pressures
Receptors cannot protect against excessive loading
Crucial mass is more important than Crucial mix


BIOMECHANICS


MUSCLES
Microscopic features
Arrangement of the muscle fibers


TYPES OF MUSCLE FIBERS
SLOW MUSCLE FIBERS- TYPE I
MASSETER & MEDIAL PTERYGOID
POST FIBERS OF THE TEMPORALIS
LATERAL PTERYGOID

FAST MUSCLE FIBERS- TYPE II
POST FIBERS OF MASSETER AND MEDIAL PTERYGOID
TEMPORALIS SUPERFICIAL 50%

MUSCLES OF THE MASTICATION
INTERMDIATE FIBERS
TYPE II C


MUSCLES OF MASTICATION


MASSETER


FEATURES

SUPERFICIAL

DEEP

ORGIN

Zygomatic process

Anterior two thirds of
zygomatic arch

INSERTION

Angle and lower
portion of mandible

Upper portion of the
lateral aspect of ramus

ORIENTATION

Oblique downwards

Vertically downwards

FUNCTIONS

Protruding of
mandible

Stabilizing condyle
against the articular
eminence


TEMPORALIS
Fan shaped muscle
ORIGIN- Temporal fossa & the
lateral surface of the skull
INSERTION- Forms a tendon
inserts into coronoid process and
the anterior border of the ramus


DIVISIONSANTERIOR MIDDLE
POSTERIOR -

Directed vertically
Oblique orientation
Horizontally

More concerned with moving and stabilizing the mandible


MEDIAL PTERYGOID
ORIGIN- Medial portion of the lateral pterygoid plate
- maxillary tuberosity
INSERTION- medial portion of the angle of mandible
FUNCTIONS- Elevating and protrusion of the mandible
-Unilateral contraction mediotrusive movement


LATERAL PTERYGOID
Two divisions- INFERIOR LATERAL PTERYGOID
SUPERIOR LATERAL PTERYGOID
INFERIOR HEADORIGIN- outer surface of the lateral
pterygoid plate
INSERTION- neck of the condyle
FUNCTIONS- Protrusion when contracts
simultaneously
- Mediotrusive motion when
contracts unilaterally


SUPERIOR HEADORIGIN- Infratemporal surface of of the
greater wing of the sphenoid
INSERTION- FOUR TYPES


I

Insertion into the condyle by merging into the central tendon

II Insert directly into pterygoid fovea(60 – 70 %)
III Blend with the fibers of the capsule
IV Insert directly into the medial portion of the disk (30 %)

FUNCTIONSActive during the closing especially during the
power stroke

DIGASTRICS
POSTERIOR BELLY –
Origin- Mastoid notch
Fibers- Downwards forwards and inwards
Attachment- Hyoid bone
ANTERIOR BELLYOrigin- Fossa of the lingual surface of the
mandible
Fibers- Downward and backward
FUNCTION – Depression of the mandible

TYPES OF MOVEMENT
ROTATIONAL MOVEMENT
HORIZONTAL AXIS
FRONTAL AXIS
SAGITTAL AXIS

TRANSLATIONAL MOVEMENT
SINGLE PLANE BORDER MOVEMENTS

HORIZONTAL AXIS

HINGE AXIS


FRONTAL AXIS


SAGITTAL AXIS


TRANSLATION MOVEMENT
Definition
Occurs in the superior joint
cavity
Both hinge and the translation
occurs simultaneously


SAGITTAL PLANE BORDER
MOVEMENTS
FOUR COMPONENTS

Posterior
Anterior
Superior
Functional


HORIZONTAL BORDER
MOVEMENTS

L

R


FRONTAL BORDER MOVEMENTS


ENVELOPE OF MOTION


BENNETT MOVEMENT & ANGLE


ARTICULAR DISK


ELEVATION

SUMMARY

TEMPORALIS

RETRACTION

MASSETER &
MEDIAL PTERYGOID

PROTRACTION

DIAGASTRIC
&
GENIOHYOID

LATERAL
PTERYGOID

DEPRESSION

ARTHROSCOPY OF TMJ
Kenji Takagi Japan first introduced this technique
Insertion of an rigid endoscope into the joint compartment for
observation and therapeutic purpose
Arthrography is mandatory before this procedure- Joint space


INSTRUMENTATION
TV camera and video
Scopes - 2.4, 1.9, 1.7 mm
Sheath - 2.7, 2.4 , 2 mm
Light source – xenon arc
illuminator


TECHNIQUE


NORMAL JOINT


REFERENCES
LASKIN- Temporomandibular joint
CARLSSON, SESSLE, MOHL,ZARB- Temporomandibular And
masticatory muscle disorders
BERKOVITZ- Oral anatomy
J.P OKESON- Temporomandibular disorders


IDE NAKAZAWA –Anatomical atlas of TMJ
TENCATE – Oral histogy
Koski et al , 1968 AJO-DO
MAJOR M ASH-Wheelers dental anatomy, Physiology and
occlussion


T.M GRABER ,T RAKOSI, A G PETROVIC- Dentofacial
orthopedics with functional appliances




Ct fig


MRI fig

Thank you
Leader in continuing dental education


TMJ /certified fixed orthodontic courses by Indian dental academy

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