Temporomandibular joint/ fellowships in orthodontics

1
TEMPOROMANDIBULAR JOINTTEMPOROMANDIBULAR JOINT
INDIAN DENTAL ACADEMY
Leader in continuing dental education
www.indiandentalacademy.com

2
Temporomandibular joint
Types of joints
Embryology
Functional anatomy
Muscles of mastication
Biomechanics of TMJ
Evolution

3
Types of jointsTypes of joints
Depending on the types of tissues involved
1. Fibrous joints
2. Cartilaginous joints
3. Synovial joints

5
Fibrous jointsFibrous joints
1. Sutures
2. Gomphosis
3. syndesmosis

6
Cartilaginous jointsCartilaginous joints
1. Primary
2. secondary

7
Synovial jointsSynovial joints
Permits significant movement
Synovial cavity
Synovial membrane
 Synovial fluid
hyaline cartilage
capsule

8
Synovial jointsSynovial joints
• Uniaxial/biaxial /multiaxial
• Planar /ginglymoid
/pivot/condyloid/saddle/ball and socket
• Hiltons law
• Muscles acting upon a joint have same
nerve supply as joint

9
TMJTMJ
GINGLYMOID
DIARTHROIDAL
SYNOVIAL
TRUE COMPOUND

10
TMJ OTHER SYNOVIAL
JOINTS
2 BLASTEMA
-Temporal
-Condylar
Cavity formation within a
single blastema
Fibrous cartilage at the
articular surfaces
Hyaline cartilage at the
articular surfaces.
Cartilage acts as growth
centre
Does not

11
Types of joints
Embryology
 Evolution

12
EmbryologyEmbryology
 Primary Jaw joint
Homologous reptiles.
 -maeckels cartilage
functions as the primary
joint.mouth opening
begins
 Persists till 4 months IUL
6 weeks iu.-Membranous
bone forms lateral to
meckels cartilage at-body
and ramus

13
 10th
week-the joint forms both
malleo- incudal and Definite
jaw joint move together in
synchrony for 8 weeks in
fetal life. The accessory
mandibular condylar
cartilage develops as 1st
blastema..
 Grows towards the later
developing temporal
blastema.

14
 -Lateral pterygoid develops medial to future
condyle and causes movement at through the
primary meckelian joint.
 Fossa
 Interposed connective tissue becomes thinner.
 Two clefts develop in the fibrous connective
tissue forming two joint cavities.

15
1st
inferior compartment
2nd
superior compartment.
Invading synovial membrane compartment.
Cavitation.
Early immobilization
Early functional activity

16
Clefting and
formation of
joint cavity
Formation of
condylar +
temporal
blastema and
ossification

17
Articular disc-biconcave.
Ventarally –lpm
Dorsally –the superior laminae,inferior
laminae

18
Fossa – flat
Articular tubercle
 Absent condyle,no
fossa/tubercle

19
Types of joints
Embryology
Evolution

20
3 components that make up the masticatory
system
1. Maxillae
2. Mandible
3. Temporal bone

21
TMJTMJ
GINGLYMOID
DIARTHROIDAL
SYNOVIAL
TRUE COMPOUND

22
FUCTIONAL ANATOMYFUCTIONAL ANATOMY
SQUAMOUS PART OF TEMPORAL
BONE
ARTICULAR DISC
CONDYLE

23
condylecondyle
 Poles of condyle
 Convex
articulating
surface
 Articulating
surface –ant and
post

24
Temporal boneTemporal bone
 Squamous part
 Concave-Glenoid fossa
 Squamotympanic fissure
 Articular eminence
 Roof - thin

25
ARTICULAR DISCARTICULAR DISC
ANTERIOR
BORDER
INTERMEDIATE
ZONE
POSTERIOR
BORDER
SAGITTAL
VIEW
ANTERIOR
VIEW

26
Devoid of blood vessels and nerve
Flexible and adaptable to functional
demands

27
Attachments of the articular disc-Attachments of the articular disc-
Retrodiscal tissue-
 Loose connective tissue
 Rich blood and nerve
supply
 Bilaminar zone
Superior retrodiscal
lamina(elastic fibres)
Inferior retrodiscal
lamina(collagenous fibres)

28
Retrodiscal
tissue
Temporal bone
condyle
Capsular
ligament +
superior
LPM
Medially + laterally attached to the capsule which divides
joint cavity
Attachments of the articular discAttachments of the articular disc --

29
 Articulating surfaces are covered with fibrous
tissue
 Synovial lining /fluid
Upper joint
cavity
Lower
joint cavity

30
Functions of synovial fluidFunctions of synovial fluid
I. Nutrition
II. Lubrication
1. Boundary lubrication (moving joint)
2. Weeping lubrication(compressive
forces)
• Minimizes friction

31
Ligaments of TMJLigaments of TMJ
 Limit joint movement
1. Collateral ligaments
2. Capsular ligaments
3. Temporomandibular ligaments
4. Sphenomandibular ligaments
5. Stylomandibular ligaments
Functional
ligaments
Accessory
ligaments

32
Collateral (discal) ligamentCollateral (discal) ligament
1. Medial discal
2. Lateral discal
 Divide joint medio laterally
 Allows passive movement of
the disc
 Permits anterior + posterior
rotation of disc on condyle
 Blood vessels + nerves
 Proprioception

33
Capsular ligamentCapsular ligament
Surrounds the TMJ
Resists forces that
separate the
articulating
surfaces
proprioception

34
Temporomandibular ligamentTemporomandibular ligament
1. Outer oblique portion
2. Inner horizontal portion
 Reinforces capsular
ligament
 OOP- Prevents
excessive dropping of
condyle / limits extent
of mouth opening
IHP

35
Temporomandibular ligament-Temporomandibular ligament-
actionaction
• Limits rotational
opening
• Seen only in
humans – erect
posture
• Prevents damage
to submandibular /
retromandibular
structures

36
Temporomandibular ligamentTemporomandibular ligament
 IHP-
 Limits posterior
movement of
condyle and disc
 Prevents damage
to the retrodiscal
tissue

37
Sphenomandibular ligamentSphenomandibular ligament
Extents from
spine of
sphenoid to
lingula
No significant
limiting effects
on mandibe

38
Stylomandibular ligamentStylomandibular ligament
Extends from the
styloid process to
the angle + post
border of ramus
Limits excessive
protrusive
movement

39
Types of joints
Embryology
Evolution

40
Muscles of masticationMuscles of mastication
Masseter
Temporalis
Medial pterygoid
Lateral pterygoid
Digastric
Muscles of masticationMuscles of mastication

41
The masseterThe masseter
Origin insertion &
direction
Function –elevation

42
The temporalisThe temporalis
Origin & insertion
Function –
elevation
retrusionwww.indiandentalacademy.com

43
The medial pterygoidThe medial pterygoid
 Origin & insertion
Function - elevation
Protrusion
Muscle sling with Masseter
U/l - mediotrusive

44
The lateral pterygoid- inferiorThe lateral pterygoid- inferior
portionportion
Origin & insertion
Function-protrusion
U/l – mediotrusive
With depressors – downward+forward

45
The lateral pterygoid- superiorThe lateral pterygoid- superior
portionportion
Infratemporal surface
of greater wing of
sphenoid – capsule
,disc ,neck
Active during
power stroke
Closure with
elevators

46
The lateral pterygoidsThe lateral pterygoids
Exert medial pull on disc & condyle

47
The digastricusThe digastricus
Function– b/L contraction depression of mandible
with fixed hyoid bone
Raises hyoid –swallowingwhen mandible is fixed

48
Other muscles coordinatingOther muscles coordinating
Mandibular movementsMandibular movements
Coordinated
movements of-
Supahyoid
Infrahyoid
Posterior neck muscles

49
Summary ofSummary of
mandibularmandibular
movements &movements &
musclesmuscles
involvedinvolved

50
Types of joints
Embryology
Evolution

51
Biomechanics of TMJBiomechanics of TMJ
 Based on structure and function can be divided
into 2 systems
 First joint system
-Inferior joint cavity
• Second joint system
-Superior joint cavity

52
 Articular disc as meniscus
1. Not a determinant of joint movement
2. Attached on one side and unattached on
the other.
3. Freely extends into the joint space

53
TMJ - no attachment
Yet stable due to muscles
Resting stage – tonus
Increase muscle activity - increase
interarticular pressure
Absence of pressure - dislocate

54
Disc space varies with
pressure
 Increased – disc space
narrows
 Decreased – space widens
Condyle on anterior /
posterior zone

55
Mandibular opening and closingMandibular opening and closing
SRL –retract the
disc
Closed joint
position – relaxed
Stretched – during
opening

56
Mandibular opening and closingMandibular opening and closing
 SLP – protractor of the
disc
 ILP – protractor of
condyle
 So forward movement
– articular cartilage –
disc morphology.
opening
closing

57
closed mouth restingclosed mouth resting
positionposition SLP - tonus
 SLP > SRL
 Resting position-interarticular pressure
reduced,disc space wide. Disc rotated anteriorly
 Condyle contacts intermediate & post zone
 Open mouth –SRL stretches , SRL > SLP Disc
rotated posteriorly

58

59
Power stroke / chewingPower stroke / chewing
 pressure reduced on biting side
 Fulcrum around food
 Pressure increased on contralateral side
 Same side – separation – dislocation
 SLP - active ,positions disc anteriorly on condyle
 Stabilizes joint
 Teeth approach intercuspation –pressure increases
 Mechanical post rotation – intermediate zone-
resting positionwww.indiandentalacademy.com

60
 Points to remember
1. Ligaments do not actively participate in
function of TMJ
2. Ligaments do not stretch
3. Articular surfaces must maintain constant
contact

61
Types of joints
Embryology
Evolution

62
Adaptive morphology is dependent upon-
 Locomotion
 Feeding

63
EVOLUTION OF T.M.JEVOLUTION OF T.M.J
Primitive vertebrates
Collection of food led to dev of jaws along
with fins
Amphibians and reptiles
 Greater demand on jaw mechanics to adjust
to new habitat

64
Mammals
 Greater benefit from food source
 Modification in jaws, joint, dentition
Humans
 Upright posture
 Bipedal locomotion
 Shrinkage of human face

65
1.Prehension
2.Control size of mass of food entering
alimentary tract
-sharp cusps
-force in a direction effective
-sharp cutting edges
Earliest functional activity ofEarliest functional activity of
TMJTMJ

66
Jaw joint has been classified into-Jaw joint has been classified into-
1.Primitive jaw jointreptilian jaw
jointquadrate-articular occlusion
2.Mamalian type of jaw jointdentary
squamosal articulationearly TMJ

67
Primitive jaw joint –reptilian
joint
Maxillae
 Palatoquadrate bar
Mandible
 Hyomandibular(stapes)
 Quardate(incus)
 Articulare(malleus)
 Dentary
Dentary –squamosal
joint/mammalian jaw
joint

68
Most primitive jaw
Flexible plate of fibrocartilage connects the
upper and lower cartilagenous jaws(shark)
-1st
arch no longer forms the gill and grows under
the brain as palatoquadrate bar.It extends front
to back under the base of the skull to join the
lower jaw(maeckels cartilage )at the
epiceratobranchial joint.
The second arch modified to support the first
arch in its function-hyomandibular cartilage.

69
AMPHISTYLIC SUSPENSION
Upper jaw connected to cranium-2 places
Behind
eye
Hyomandibular cartilage attached to
cranium
Relationship of primitive jaw andRelationship of primitive jaw and
cranial basecranial base

70
HYOSTYLIC SUSPENSION
. Hyomandibular element was the only
articulation between the jaws and the
cranial base

71
Autostylic suspension
Upper jaws are firmly fused to the cranial base.eg
chimera

72
STREPTOSTYLIC SUSPENSION
Great degree of movement between jaws
and cranial base
Assists in swallowing
 Reptiles and modern snakes
The pterygopalatine component can remain
clamped onto the animal while other parts
shifted their grip

73
Amphibians and higher vertibrates
Maxillary palatine , pterygoid elements
attached to the cranium,but hyomandibular
(stapes) ,quadrate (incus) and articulare
(malleus) continued to form movable joint.
Mobility of upper and lower jawsMobility of upper and lower jaws

74
Bones dentine and enamelBones dentine and enamel
Bones dentine and enamel first appeared in
fossil records as-dermal plates of primitive
creatures.
In primitive sharks the denticles extend into
the jaws to give rise to teeth. The dermal
bones sank into the skin . They gained
attachment to muscles.

75
``
 Pre maxillae-with ant teeth
 Maxillae – with marginal teeth
 Jugal bone-lower orbit
 Quadrato-jugal
 Quadrate
 Squamosal bone
The bones at the margin of upper jaw-

76
Maeckels cartilage(core of the lower
jaw)became invested in 8 separate dermal
bony plates.
 Dentary(with marginal row of teeth)
 2 spenials
 Angular
 Surangular
 Prearticular
 2 coronoid bones
Lower jawLower jaw

77
Development of musclesDevelopment of muscles
Advanced reptiles – capitii
mandibularis and
pterygoid muscles.
Well divided muscles
Increased functional
activity
Size of dentary
bone,heterodont dentition

78
Development of musclesDevelopment of muscles
Alteration in orientation of jaw
muscles
Forces directed away from the
joint

79
Development of inter-articularDevelopment of inter-articular
discdisc
 Primitive joint did not have any cartilage.
Lateral part of the muscle that extended
from the pterygoid region to the maeckels
cartilage gives rise to the cartilage.

80
Functional activity of theFunctional activity of the
mamalian TMJmamalian TMJ
Prehension
Tearing
Crushing

81
Prehension
 Condyle clamped by
glenoid processes
 Reptiles have enlarged
teeth at corners

82
PrehentionPrehention
1. Speed
-temporalis muscle
2. Constant reproduction of jaw closure
-interlocking canines
-hinge like tmj

83
TearingTearing
 Combination of –
muscles controlling
the dentition and
movement of the jaws
–neck muscles
 Carnivore dentition
 Grazing activity of the
ungulate

84
CrushingCrushing
1. Slicing (carnivores)
2. Gnawing (rodent incisors)
3. Grinding (herbivores)

85
Slicing in carnivoreSlicing in carnivore
 Well dev canines
 Condyle encircled in fossa
at level of occlusal surface
of mandibular teeth
 Coronoid – large
 Disc present
 Right and left halves are
not united at the
symphysis.

86
Slicing in carnivoreSlicing in carnivore
 Masseter +temporalis
–well dev
 Zygomatic arch-strong
 No forward
 Minimum lateral

87
Rodent - gnawingRodent - gnawing
Incisors chisel
shaped
Continuous erruption
Differential wear
Ant –post oriented
glenoid fossa
No side to side
movement

88
 Well dev molars
 Ascending ramus increased
height
 Condyle oval
 No articular eminence
 Slight post glenoid process
 Capsule is present.
 Anisognathous-do not
occlude simultaneously.
Herbivore - grinding

89
 Disc & capsule present
 Masseter + temporalis well dev
but not as much as the
carnivores.
 Lat pterygoid
 Lateral movements prominent
Herbivore - grinding

90
ReferencesReferences
JEFFEREY P OKESON
GUNNAR E CARLSSON
 RICHARD TEN CATE
GRAYS ANATOMY

www.indiandentalacademy.com 91

Temporomandibular joint/ fellowships in orthodontics

Recommended

Recommended

More Related Content

What's hot

What's hot (20)

Viewers also liked

Viewers also liked (20)

Similar to Temporomandibular joint/ fellowships in orthodontics

Similar to Temporomandibular joint/ fellowships in orthodontics (20)

More from Indian dental academy

More from Indian dental academy (20)

Recently uploaded

Recently uploaded (20)

Temporomandibular joint/ fellowships in orthodontics