temporomandibular joint-development and anatomy

tmj-embryology,development and anatomy

1. SEMINAR
ON
DEVELOPMENT & ANATOMY OF T.M.J
by
Dr. Sangeeta Poriya
MDS 1
ST
YEAR
Prosthodontics

2. Temporomandibular joint.
IntroductionIntroduction
DefinationDefination
EvolutionEvolution
EmbryologyEmbryology
Classification of jointsClassification of joints
AnatomyAnatomy
Muscles of masticationMuscles of mastication
References.References.

3. INTRODUCTIONINTRODUCTION
““FUNCTION MUST BE UNDERSTOOD FUNCTION MUST BE UNDERSTOOD
BEFORE DYSFUNCTION CAN HAVE BEFORE DYSFUNCTION CAN HAVE
MEANING”MEANING”
Masticatory system a functional unit of body Masticatory system a functional unit of body
includes TMJ .includes TMJ .
Is responsible for chewing, speaking, swallowing Is responsible for chewing, speaking, swallowing
etcetc
It is most complex joint of body. It is most complex joint of body.
Hence its functions should be understood Hence its functions should be understood
before resulting in its dysfunction.before resulting in its dysfunction.

4. TMJ Defination TMJ Defination
 The articulation between the temporal bone and The articulation between the temporal bone and
the mandible. It is diarthoidal,bilateral ginglymus the mandible. It is diarthoidal,bilateral ginglymus
joint (GPT).joint (GPT).
The area where craniomandibular articulation The area where craniomandibular articulation
occurs is called the temporomandibular joint.occurs is called the temporomandibular joint.
The TMJ provides hinging movement in one The TMJ provides hinging movement in one
plane and is considered as a ginglymoid joint.plane and is considered as a ginglymoid joint.
 It also provides gliding movements, which It also provides gliding movements, which
classifies it as an arthrodial jointclassifies it as an arthrodial joint

5. EVOLUTION OF TMJ.EVOLUTION OF TMJ.
Primitive vertebratesPrimitive vertebrates
Collection of food led to dev of jaws along with Collection of food led to dev of jaws along with
fins.fins.
Amphibians and reptilesAmphibians and reptiles
Greater demand on jaw mechanics to adjust to Greater demand on jaw mechanics to adjust to
new habitat.new habitat.

6. EVOLUTION OF TMJ.EVOLUTION OF TMJ.
Increasing efficiency of the feeding mechanism- Increasing efficiency of the feeding mechanism-
critical factor in vertebrate evolution.critical factor in vertebrate evolution.
Earliest functional activity of TMJ.Earliest functional activity of TMJ.
prehension Control size of mass
of food entering
alimentary tract

7. EVOLUTION OF TMJ.EVOLUTION OF TMJ.
Mammals Mammals
Greater benefit from food source Greater benefit from food source
Modification in jaws, joint, dentitionModification in jaws, joint, dentition
HumansHumans
Upright posture / bipedal locomotionUpright posture / bipedal locomotion
Food collection shifted to jaws.Food collection shifted to jaws.

8. EVOLUTION OF TMJ.EVOLUTION OF TMJ.
Primitive jaw joint – Primitive jaw joint –
reptilian jointreptilian joint
1.1.DentaryDentary
2.2.Quardate(incus)Quardate(incus)
3.3.Articulare(malleus)Articulare(malleus)
Dentary –Dentary –
squamosal squamosal
joint/mammalian joint/mammalian
jaw jointjaw joint

9. EVOLUTION OF TMJ.EVOLUTION OF TMJ.
Relationship of primitive jaw and cranial base.Relationship of primitive jaw and cranial base.
AMPHISTYLIC SUSPENSIONAMPHISTYLIC SUSPENSION
 upper jaw connected to cranium.upper jaw connected to cranium.
HYOSTYLIC SUSPENSIONHYOSTYLIC SUSPENSION
Only lower jaw connected to cranium.Only lower jaw connected to cranium.
Behind
eye
Hyomandibular
cartilage attached
to cranium

10. EVOLUTION OF TMJ.EVOLUTION OF TMJ.
STREPTOSTYLIC SUSPENSIONSTREPTOSTYLIC SUSPENSION
Great degree of movement between upper and lower Great degree of movement between upper and lower
jawjaw
Assists in swallowingAssists in swallowing
Amphibians and reptiles Amphibians and reptiles
Maxillary , pterygoid elements attached to the Maxillary , pterygoid elements attached to the
craniumcranium

11. EVOLUTION OF TMJ.EVOLUTION OF TMJ.
Development of muscles.Development of muscles.
Advanced reptiles – capitii Advanced reptiles – capitii
mandibularismandibularis
Increased functional activityIncreased functional activity
Size of dentary bone,Size of dentary bone,
heterodont dentitionheterodont dentition
Forces directed away from Forces directed away from
the jointthe joint
Alteration in orientation of jaw Alteration in orientation of jaw
musclesmuscles

12. EVOLUTION OF TMJ.EVOLUTION OF TMJ.
Mammal like reptiles - Prehension Mammal like reptiles - Prehension
Condyle clamped Condyle clamped
by glenoid by glenoid
processesprocesses

13. EVOLUTION OF TMJ.EVOLUTION OF TMJ.
Carnivore - cuttingCarnivore - cutting
Well dev caninesWell dev canines
Coronoid – largeCoronoid – large
Condyle encircled in fossaCondyle encircled in fossa
Disc presentDisc present
Masseter +temporalis –Masseter +temporalis –
well devwell dev
No forward No forward
Minimum lateralMinimum lateral

14. EVOLUTION OF TMJ.EVOLUTION OF TMJ.
Rodent - gnawingRodent - gnawing
Incisors chisel Incisors chisel
shapedshaped
Ant –post Ant –post
oriented glenoid oriented glenoid
fossafossa
Forward Forward
+upward +upward
movement movement
Well dev Well dev
MasseterMasseter

15. EVOLUTION OF TMJ.EVOLUTION OF TMJ.
Herbivore - grindingHerbivore - grinding
Well dev molarsWell dev molars
Ascending ramus Ascending ramus
increased heightincreased height
Condyle ovalCondyle oval
No articular eminenceNo articular eminence
Post glenoid processPost glenoid process
Disc & capsule presentDisc & capsule present
Masseter + temporalis Masseter + temporalis
well devwell dev
Lat pterygoidLat pterygoid
Lateral movements Lateral movements
prominentprominent

16. Embryology.Embryology.
Primary Jaw jointPrimary Jaw joint
Between Incus and MalleusBetween Incus and Malleus
Persists till 4 months IULPersists till 4 months IUL

17. Embryology.Embryology.
Secondary jaw jointSecondary jaw joint
Between the condyle and temporal boneBetween the condyle and temporal bone
Differs from other synovial jointsDiffers from other synovial joints

18. Embryology.Embryology.
TMJ - neonateTMJ - neonate
Lax Lax
Stability –capsuleStability –capsule
Fossa – flatFossa – flat
Articular tubercleArticular tubercle
 absent condyle,no absent condyle,no
fossa/tuberclefossa/tubercle

19. DEVELOPMENTDEVELOPMENT
•Meckel’s cartilage provide skeletal support for Meckel’s cartilage provide skeletal support for
development of lower jaw.development of lower jaw.
• The primary jaw joint The primary jaw joint
 - Articulation of Meckel’s cartilage with - Articulation of Meckel’s cartilage with
 Incal cartilage Incal cartilage
 - exists for 4 months till cartilages ossify - exists for 4 months till cartilages ossify
 & are incorporated in middle ear.& are incorporated in middle ear.
Secondary jaw joint-TMJ begins to form at 3 Secondary jaw joint-TMJ begins to form at 3
 months of gestation months of gestation

20. •Most synovial joints have appeared by 7Most synovial joints have appeared by 7
thth
wk in wk in
utero as a cavitation.utero as a cavitation.
•TMJ arises from 2 widely separated centers that TMJ arises from 2 widely separated centers that
grow towards each other.grow towards each other.
•Regions of mesenchymal condensation – Regions of mesenchymal condensation –
temporal & condylar blastemas.temporal & condylar blastemas.
•Meniscus is formed- pair of clefts develop in Meniscus is formed- pair of clefts develop in
interposed condensation of mesenchyma which interposed condensation of mesenchyma which
form upper and lower joint cavities.form upper and lower joint cavities.

21. • 12 wks in utero- condylar blastema differentiates 12 wks in utero- condylar blastema differentiates
into a condylar cartilage.into a condylar cartilage.
• The cartilage is replaced by membraneous bone & The cartilage is replaced by membraneous bone &
it’s posterior part persists in the condyle – site of it’s posterior part persists in the condyle – site of
active growth. active growth.
• Further adaptation of condylar morphology- Further adaptation of condylar morphology-
functional & environmental changes.functional & environmental changes.
• Capsule develops by condensation of Capsule develops by condensation of
surrounding mesenchyma- isolates the joint.surrounding mesenchyma- isolates the joint.

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

24. CLASSIFICATION OF JOINTSCLASSIFICATION OF JOINTS
BASED ON BASED ON
ANATOMICAL ANATOMICAL
CHARACTERISTICS CHARACTERISTICS
(Structural (Structural
classification)classification)
BASED ON BASED ON
FUNCTIONAL FUNCTIONAL
CLASSIFICATION: CLASSIFICATION:
( type of movement)( type of movement)

25. STRUCTURAL CLASSIFICATION:
Based on presence or absence of joint cavity:
FIBROUS JOINT:
CARTILAGENOUS JOINT:
SYNOVIAL JOINT
FUNCTIONAL CLASSIFICATION:
SYNARTHROSIS: Immovable joints
AMPHIARTHROSES: Slightly movable joints
DIARTHROSIS: Freely movable joints:
Types of joints.Types of joints.

26. SUTURE: sutura = seam
Fibrous joint composed of thin layer of dense fibrous
connective tissue that unites bones of the skull
GOMPHOSIS: to bolt together
Cone shaped peg fits into a socket eg tooth into alveolar
bone through periodontal ligament
SYNCHRONDROSIS: syn= together ,
chondros=cartilage
Cartilaginous joint in which connective material is hyaline
cartilage eg epiphyseal plate
SYNARTHROSIS: Immovable joints

27. AMPHIARTHROSES: (Slightly movable joints)
SYNDESMOSIS:band /ligament
fibrous joint in which there is considerably more fibrous
connective tissue than in a suture. The fit of the bones is
not so tight. Some amount of flexible movement. EG
distal articulation between fibula and tibia
SYMPHYSIS:growing together
Cartilaginous joint in which connecting material is broad
flat disc of fibro cartilage EG intervertebral discs.pubic
symphysis

28. DIARTHROSISDIARTHROSIS:: Also known as synovial joints. Presence of Also known as synovial joints. Presence of
Synovial cavity and articular cartilage a characteristic feature.Synovial cavity and articular cartilage a characteristic feature...
(Freely movable joints.)(Freely movable joints.)
Based on types of movement:
GLIDING : eg intercarpal joint
HINGE eg: elbow joint/ ankle
CONDYLOID eg: joint between
radius and carpals
PIVOT eg: joint between atlas and
axis
SADDLE eg : joint between
carpus and thumb
BALL AND SOCKET: eg :
shoulder/ hip joint

29. BILATERAL SYNOVIAL
GINGLYMOID (DIARTHRODIAL )
COMPOUND JOINT

30. Synovial joints.Synovial joints.
Permits significant movementPermits significant movement
Synovial cavity Synovial cavity
Synovial membraneSynovial membrane
 Synovial fluidSynovial fluid
hyaline cartilage hyaline cartilage
capsulecapsule

31. Synovial joints.Synovial joints.
Uniaxial/biaxial /multiaxialUniaxial/biaxial /multiaxial
Planar /ginglymoid /pivot/condyloid/saddle/ball and Planar /ginglymoid /pivot/condyloid/saddle/ball and
socketsocket
Hiltons lawHiltons law
Muscles acting upon a joint have same nerve supply as Muscles acting upon a joint have same nerve supply as
jointjoint

32. SYNOVIAL JOINT:
Specialized endothelial cells form a synovial lining and forms the
synovial fluid which fills both joint cavities and performs two functions:
 Medium for metabolic exchange: as the articular surfaces are
avascular
Lubricant during function:
Two mechanisms by which lubrication occurs:
BOUNDARY LUBRICATION:
primary mechanism;synovial fluid forced from one region to
another by movement of the joint itself.
WEEPING LUBRICATION:
The articular surfaces itself absorb some amount of synovial fluid
which due to the pressure during function is forced in and out of the
articular tissues and provided the medium for metabolic exchange. This
occurs only during compression but not all other movements.

33. Functions of synovial fluid.Functions of synovial fluid.
NutritionNutrition
LubricationLubrication
1.1.Boundary lubrication Boundary lubrication
2.2.Weeping lubricationWeeping lubrication
•Minimizes frictionMinimizes friction

34. COMPONENTS OF THE TMJ:
CONDYLAR HEAD
GLENOID FOSSA
ARTICULAR EMINENCE
MUSCLES OF THE TMJ:
MUSCLES OF MASTICATION
SOFT TISSUE COMPONENTS:
ARTICULAR DISC
JOINT CAPSULE
LIGAMENTS
ARTERIAL AND NERVE SUPPLY TO THE JOINT

35. CONDYLAR HEADCONDYLAR HEAD
The oval condylar head is shaped like a rugby ball The oval condylar head is shaped like a rugby ball
The lateral pole is slightly at a a lower level to the medial poleThe lateral pole is slightly at a a lower level to the medial pole
The long axis makes a line of 140 degrees with the line joining the The long axis makes a line of 140 degrees with the line joining the
external acoustic meatusexternal acoustic meatus
The cartilage layer is thicker
laterally and posteriorly
suggesting the growth
direction is more active in
these areas.
Anteromedially the cartilage
becomes thin early and bone
forms in this region of
attachment of the lateral
pterygoid

36. The glenoid fossa:
Shallow oval depression in the infratemporal area
Bone of the deepest part is quite thin and shows that this part
of the joint is not designed to play an active functional role in
the joint.
The articular
eminence:
The two slopes of the
articular eminence are
considered to be a
functional part of the
joint.
The posterior slope
resorbs with
edentulism

37. Muscles of mastication:
mastication is a a harmonious and skillful activity which requires the
presence and co ordination of not only the muscles of mastication but
also the supra infrahyoid muscles, and the facial muscles

38. Muscles of mastication.Muscles of mastication.
Masseter.Masseter.
Temporalis.Temporalis.
Medial pterygoid.Medial pterygoid.
Lateral pterygoid.Lateral pterygoid.
Digastric.Digastric.

39. The Temporalis.The Temporalis.
The strongest of the
masticatory muscles
Divided into three parts
Well developed in carnivores
and animals requiring a strong
bite force
It elevates the mandible when
it contracts.
Contraction of the anterior
part raises the mandible
Contraction of the middle part
elevates and retrudes the
mandible
Temporalis

muscle
tendon

40. The masseter.The masseter.
Powerful elevator muscle
Superficial muscle helps in
protruding the mandible
Deep portion helps in
stabilizing the condyle against
the articular eminence when
biting in a protruded position.
Unilateral movement helps in
lateral movement of the
mandible
Well developed in ruminants
Deep portion
Superficial portion

41. The medial pterygoid muscle.The medial pterygoid muscle.
Originates from the
pterygoid fossa and extends
downwards backwards and
outwards to insert in the
medial side of the ramus of
the mandible forming a
sling along with the
masseter at the angle of the
mandible.

It assists in closing of the jaw and
contraction of the muscle also causes
protrusion.

42. The lateral pterygoid muscle.The lateral pterygoid muscle.
Superior lateral pterygoid muscle
Originates form the infratemporal
surface of the greater wing of the
sphenoid, extends almost
horizontally backward and outward
to insert on the articular capsule the
disc and the neck of the condyle.
60 to 70% of the fibres attach to the
condyle and the rest to the disc.
Plays an active role not during
opening but during closing (power
stroke)

43. Originates at the outer surface of
the lateral pterygoid plate and
extends backward upward and
outward to insert into the neck of
the condyle.
When there is bilateral contraction
the condyles are pulled down the
articular eminences and the
mandible is protruded.
Unilateral contraction causes a
mediotrusive movement of that
condyle and lateral movement of
the mandible to the other side
. The inferior lateral pterygoid is
active during opening in contrast
to the superior part.

44. Other muscles coordinating Other muscles coordinating
Mandibular movements.Mandibular movements.

45. Summary of Summary of
mandibular mandibular
movements & movements &
muscles involvedmuscles involved

46. Soft tissue components of the TMJ.Soft tissue components of the TMJ.
Articular disc, capsule, ligaments and muscles

47. ARTICULAR DISC. ARTICULAR DISC.
AttachmentsAttachments
Retrodiscal
tissue
Temporal bone
condyle
Capsular
ligament +
superior
LPM
Medially + laterally attached to the capsule which divides
joint cavity

48. Articular disc
Superior head of the
lateral pterygoid
Inferior head of the
lateral pterygoid
Articular Disc.

49. ARTICULAR DISC.ARTICULAR DISC.
ANTERIOR
BORDER
INTERMEDIATE
ZONE
POSTERIOR
BORDER
SAGITTAL
VIEW
ANTERIOR
VIEW

50. ARTICULAR DISC.ARTICULAR DISC.
Articulating surfaces are covered with fibrous tissueArticulating surfaces are covered with fibrous tissue
Synovial lining /fluidSynovial lining /fluid
Upper joint
cavity
Lower
joint cavity

51. ARTICULAR DISC.ARTICULAR DISC.
Devoid of blood vessels and nerveDevoid of blood vessels and nerve
Morphology maintainedMorphology maintained
Flexible and adaptable to functional demandsFlexible and adaptable to functional demands

52. ARTICULAR DISC.
Divides the joint into two compartments
According to Rees divided into 4 parts:
Anterior band –thickened
Intermediate band- narrow and thin
Posterior band – again thick
Bilaminar zone-
upper part having ELASTIC fibres and
attaching to the posterior margin of the glenoid
fossa and the tympano squamous fissure,
forms the posterior border of the upper
compartment.
lower part: mainly collagen fibres and attached
to neck of condyle.
Posterior border of the lower compartment.

53. Articular disc
Joint capsule
Lateral ligament of the
TMJ
Articular disc has the shape of a laterally wide ovoid.
In frontal section the disc is wedge shaped thicker medially
and thinner laterally

54. Articular disc
Joint capsule
The intermediate band: It is the functional zone of the disc
Blood vessels are rarely found here in the intermediate part of
the disc

55. Unlike other synovial joints the TMJ
condyle and temporal bone do not fit
together in the absence of the disc.
The disc fills the wedge like gap and
stabilizes the join during rotation and
translation.
Normally there is no space between the disc and the
articulating bones except the antero- superior and inferior
recesses and the postero -superior and inferior recesses.
These recesses are filled with synovial fluid and movement of
the joint squeezes them into the other recesses so a thin film of
lubricant is obtained on the moving parts.
The disc also acts as a shock absorber.

56. They are made up of collagenous connective tissue which do
not stretch and do not actively participate in the normal function
They act as guide wires restricting certain movements while
permitting certain others.
They restrict movement mechanically as well as through neuro
muscular reflex activity.
Ligaments do not stretch. They can be elongated by traction
forces but once they have been elongated joint activity is usually
compromised.
LIGAMENTS:LIGAMENTS:

57. Ligaments of TMJ.Ligaments of TMJ.
Collateral ligaments(Discal).Collateral ligaments(Discal).
Capsular ligamentsCapsular ligaments
Temporomandibular ligamentsTemporomandibular ligaments
Sphenomandibular ligamentsSphenomandibular ligaments
stylomandibular ligamentsstylomandibular ligaments
Functional
ligaments
Accessory
ligaments

58. The collateral ligaments (discal).
Attach the medial and lateral poles of the articular disc to the
poles of the condyle. They are two in number:- medial and
lateral .
They function in allowing the disc to move passively with the
condyle as it glides anteriorly and posteriorly.
They also allow the disc to be rotated anteriorly and
posteriorly on the articular surface of the condyle..
Thus these ligaments are responsible for the hinging
movements of the condyle which occurs in the lower
compartment.

59. Capsular ligament.
The capsular ligament encompasses the joint retaining the
synovial fluid. It is fibroelastic, very well vascularised and
well innervated and provides proprioceptive feedback
regarding the position and movement of the joint.
.
Capsular ligament
Lateral ligament

60. Temporomandibular ligament.Temporomandibular ligament.
Reinforces the lateral Reinforces the lateral
aspect of capsular aspect of capsular
ligamentligament
Outer oblique portion Outer oblique portion
Inner horizontal Inner horizontal
portionportion
OOP- Prevents OOP- Prevents
excessive dropping of excessive dropping of
condyle / limits extent condyle / limits extent
of mouth openingof mouth opening
IHP

61. TM ligament.
It has two parts outer oblique and an inner horizontal.
The outer part extends from the articular tubercle to the neck of the
condyle
The outer oblique part has the following functions:
 It restricts excessive dropping of the condyle and therefore
limits the normal opening of the mandible.
Secondly during opening of the mouth, the condyle rotates
till this ligament becomes tight as its point of insertion is
rotated posteriorly. When it becomes taut the neck cannot
rotate any further.
This unique feature is found only in humans preventing excessive
rotation for the mandible from impinging on the vital mandibular
and retromandibular structures behind the jaw.

62. the inner horizontal part extends backwards from the
articular tubercle to insert into to the lateral pole of the
condyle and posterior part of the articular disc.
Function:
The inner horizontal portion protects the posterior
retrodiscal tissues from trauma and also prevents the lateral
pterygoid muscle from over lengthening.

63. Accessory ligaments:
Sphenomandibular ligament
Stylomandibular ligament.
It becomes taut
when the mandible is protruded
and thus limits the excessive
protrusive movements of the
mandible.

64. Sphenomandibular ligament.Sphenomandibular ligament.
Extents from spine Extents from spine
of sphenoid to of sphenoid to
lingulalingula
No limiting effects No limiting effects
on mandibeon mandibe

65. Stylomandibular ligament.Stylomandibular ligament.
Extends from the Extends from the
styloid process to styloid process to
the angle + post the angle + post
border of ramusborder of ramus
Limits excessive Limits excessive
protrusive protrusive
movementmovement

66. Vascular supply:
Superficial temporal artery
Middle meningeal artery
Maxillary artery
Innervation:
Auriculotemporal nerve
Deep temporal and
masseteric nerve
Others : deep auricular ,
anterior tympanic,
ascending pharyngeal
VASCULAR SUPPLY
AND INNERVATION
OF THE JOINT

67. Blood SupplyBlood Supply
Branches from superficial temporal and Branches from superficial temporal and
maxillary arterymaxillary artery
Nerve supplyNerve supply
 a. Auriculotemporal nervea. Auriculotemporal nerve
 b. Masseteric nerveb. Masseteric nerve

68. RefrencesRefrences
Jeffrey P .Okeson, Management of Jeffrey P .Okeson, Management of
temporomandibular disorder and occlusion, temporomandibular disorder and occlusion,
55
thth
edition;8-26; 258-74. edition;8-26; 258-74.
Gray’s Anatomy 34Gray’s Anatomy 34
thth
edition;459-61. edition;459-61.
White & Pharoah; Oral radiology principles and White & Pharoah; Oral radiology principles and
interpretation,5interpretation,5
thth
edition;538-49. edition;538-49.
UdoStratmann, et al Journal of Prosthodontic UdoStratmann, et al Journal of Prosthodontic
Dentistry 2000 (3):548-54; Dentistry 2000 (3):548-54; CLINICAL CLINICAL
ANATOMY AND PALPABILITY OF THE ANATOMY AND PALPABILITY OF THE
INFERIOR LATERAL PTERYGOID MUSCLEINFERIOR LATERAL PTERYGOID MUSCLE