anatomy and physiology of TMJ for orthodontics.

1. ANATOMY AND PHYSIOLOGY OF
TEMPOROMANDIBULAR JOINT
PRESENTED BY - DR. AKSHAY KARVE 1ST YEAR MDS

2. CONTENT -
• DEFINATIONS AND TYPES OF JOINTS
• INTRODUCTION OF TMJ
• DEVELOPMENT OF TMJ
• ANATOMY OF TMJ
- bony components
- soft tissue components
- muscles related to TMJ
- blood supply of TMJ

3. - Nerve supply of TMJ
• PHYSIOLOGY OF TMJ
- joint systems
- movement of articular disk with movement of TMJ.
- functional movements of TMJ.
- envelop of the motion
• Conclusion

4. DEFINATIONS AND TYPES OF JOINTS -
WHAT IS JOINT ?
- A joint is a junction between two or more bones or cartilages . It is a device to permit
movement.
Classification of joints –
- Joints are classified basis on - 1.structure.
2.function.
3.regional.
4. articulating bones.

5. STRUCTURAL CLASSIFICATION OF JOINTS
Fibrous joints Cartilaginous joints Synovial joints
sutures
syndesmosis
gomphosis
Primary cartilaginous joints
Secondary cartilaginous joints
Plane synovial joints
Hing joints
Pivot joints
Condylar joints
Ellipsoid joints
Saddle joints
Ball and socket joints

6. Fibrous joints
Cartilaginous joints

7. Synovial joints

8. FUNCTIONAL CLASSIFICATION
• Synarthrosis (immovable) – like sutures of the skull and epiphyseal plates of young
bone
• Amphiarthrosis (slightly movable) – like secondary cartilaginous joints e.g. inter-
vertebral joint
• Diarthrosis (freely movable) – like synovial joints

10. REGIONAL CLASSIFICATION
1. skull type – immovable
2. Vertebral types – slightly movable
3. Limb types – freely movable

11. NUMBER OF ARTICULATING BONES -
• Simple joint – when only two bones articulates e.g. interphalangeal joint
• Compound joint – when more than two bones articulate in one capsule. e.g.
radiocarpal joint
• Complex joint – when joint cavity is divided by an intra-articular disc . E.g.
temporomandibular joint .

13. INTRODUCTION OF TEMPOROMANDIBULAR JOINT
• The temporomandibular joint is a synovial joint
between the mandibular fossa of squamous part
of the temporal bone above and the mandibular
condyle below.
• It also called as -1. ginglymoarthrodial joint
2. Hilton joint.
3. craniomandibular joint

14. GINGLYMOARTHRODIAL JOINT

15. HILTON JOINT.
• Hilton’s law - the muscle acting on joint
having same nerve supply as the joint
- In temporomandibular case
that is auriculotemporal, deep temporal and
masseteric nerves.

16. DEVELOPMENT OF TEMPOROMANDIBULAR JOINT
• The temporomandibular joint is a secondary development in both evolutionary
and embryological history
• In the human foetus, the primitive joint with in Meckel’s cartilage (before malleus
and incus form ) functions briefly as a jaw joint .
• In contrast to other diarthrodial joints TMJ is last joint to start develop in about
7th week in utero.

18. • Three phases of development of TMJ –
1. the bastematic stage (week 7-8)
2. cavitation stage (week 9-11)
3. maturation stage (after week 12)
7 week
• Condylar and temporal blastemata
8 week
• Anlage articular disc and capsule formation
9 week
• Initiation of inferior joint cavity formation
10 week
• Organization of inferior joint cavity complete.
11 week
• Organization of superior joint cavity and maturation
further

19. DEFECT IN DEVELOPMENT OF TMJ CAUSES
• Failure of cavitation procedure of one or both joints compartments results in uni-
or bilateral ankylosis.
• Functionless joint can result in mandibular maldevelopment, with masticatory
distress of varying severity
• Absence of articular disk is extremely rare, but its perforation is fairly common.

20. ANATOMY OF TEMPOROMANDIBULAR JOINT
• The temporomandibular joint is made up
of the following –
1. bony components –
a. condylar head
b. glenoid fossa
c. articular eminence
2. soft-tissue components
a. joint capsule
b. articular disk
condyl
e
Glenoid fossa
Articular
eminanc
e
Articular disc

21. c. ligaments
3. muscles associated with the TMJ
a. muscles of mastication
b. muscles attached to the joint

22. CONDYLAR HEAD
• strong upward projection from the posterosuperior part of the
ramus
• mediolateral length of condyle is 15-20mm and antero-posterior
width is 8-10mm
• it has a ‘Rugby ball’ or ‘Date stone’ shape.
• from the anterior view it has a medial and a lateral projection,
called the poles. Medial pole is generally more prominent than
lateral pole

24. • the head is covered by fibrocartilage
• the posterior articulating surface is grater
than the anterior surface
• the articulating surface of the condyle is
quite convex anteroposteriorly and only
slightly convex mediolaterally

25. 2. GLENOID FOSSA
• portion of temporal bone is made up of concave
mandibular fossa in which the condyle is situated and
which is also called the articular or glenoid fossa.
• the posterior roof of the mandibular fossa is quite
thin indicating that this area of the temporal bone is
not designed to sustained heavy forces.

27. 3. ARTICULAR EMINENCE
• immediately anterior to the glenoid fossa is a convex bony
prominence at the base of the zygomatic process of the
temporal bone called the articular eminence.
• covered by fibrocartilage the slopes are considered to be a
functional part of the joint
• articular eminence consists of thick dense bone and is
better equipped than the glenoid fossa to tolerate heavy
forces

29. 4. JOINT CAPSULE /ARTICULAR CAPSULE /CAPSULAR
LIGAMENT :
• The join capsule is the fibrous, non-elastic
sheet of connective tissue that encloses the
entire TMJ.
• capsule consists of two layers internal layer
and external layer

30. attachment of the capsular ligament on superior
aspect
a. anteriorly - articular eminence
b. posteriorly- above to squamotympanic
fissure
c. laterally – margins of glenoid fossa
- attachment of capsular ligament on inferior aspect
a. mediolaterally – to the condyle below the
pole
b. posteriorly – posterior aspect of the condylar
neck.

31. • Function of capsule
a. Act to resist any medial lateral and inferior forces that tends
to separate or dislocate the articular surfaces.
b. Encompass the joint and provide passive stability
c. it seals the joint space thereby retaining the synovial fluid
and providing lubrication.
d. capsular ligaments is well innervated and provides
proprioceptive feedbacks regarding position and movement of the joint which
provide active stabilization

32. SYNOVIAL MEMBRANE AND SYNOVIAL FLUID –
• The capsule is lined on its inner surface by a synovial membrane
• Along with the specialized synovial fringes located at the anterior boarder of the
retrodiscal tissues produces synovial fluid , which fill both the joint cavities

33. • 2 purposes
1. Medium for providing metabolic requirements to the non
vascular articular surface of the joint.
2. Lubricant between articular surfaces during function.
• 2 mechanisms by which synovial fluid lubricates are
a. Boundary lubrication
b. Weeping lubrication

34. ARTICULAR DISK
• Consists of dense fibrous connective tissue
that is avascular and devoid of nerve tissues in
the central area but has vessels and nerves in
the peripheral area.
• size is 19mm long and 13mm wide

36. • shape of the disc
a. Anterior view – disc thicker medially than
laterally.
b. Shape of disc is determined by
morphology of condyle and mandibular fossa.
c. the disc has a concavo-convex Superior
surface and a concave inferior surface

37. ATTACHMENTS OF THE DISC
A. Posterior
a. the articular disc is attached
posteriorly to the region of loose connective tissue
that is highly vascularized and innervated. This is
known as retrodiscal tissue.
b. The remaining body of the
retrodiscal tissue is attached posteriorly to a large
Venus plexus, which fills with blood as the condyle
moves forward.

38. B. Medial and lateral –
a. the articular disc contact to the
condyle medially and laterally through discal/
collateral ligaments or joint capsule.
C. Anterior -
- joint capsule
- muscles inserted into the anterior aspect
of the disc have been observed. fibres of the
superior head of the lateral pterygoid have been
observed to inserted into anteromedial 2/3rd of
the disc.
- inferiorly to articular region of condyle.

39. - upper compartment
the passive volume of
upper compartment is estimated to be
1.2mL.
- lower compartment
the passive volume of the
lower compartment is estimated to be
0.9mL.

40. POSITION OF THE ARTICULAR DISK
- As with most muscles, the lateral pterygoid is constantly maintained in a mild state of
contraction or tonus, which exerts a slight anterior and medial force on the disc.
- In the resting closed joint position , this anterior and medial force will normally
exceed the post. elastic retraction force provided by the non-stretched retrodiscal
lamina
Therefore, in the resting closed joint when the interarticular pressure is low and the disc
space widened,
the disc will occupy the most anterior rotary position on the condyle permitted by the
width of the space ( in contact with intermediate and posterior zone of the disc)

42. LIGAMENTS
• ligaments of the joints are made up of collagenous connective tissue
• They do not enter actively into joint function but instead act as a passive
restraining devices to limit and restrict border movements
TMJ has two types of ligaments –
A. 3 functional ligaments support the TMJ
B. 2 accessory ligaments

43. A. 3 functional ligaments support the TMJ :
1. Collateral ligaments/ discal ligaments
2. Capsular ligament
3. TM ligament/ lateral ligaments
B. 2 accessory ligaments :
1. Sphenomandibular ligament
2. Stylomandibular ligament

44. COLLATERAL (DISCAL) LIGAMENTS
• Attach the medial and lateral borders of the articular
disc to the poles of the condyle
• Medial discal ligament – attaches the medial edge of
the disc to the medial pole of the condyle.
• Lateral discal ligament – attaches the lateral edge of
the disc to the lateral pole of the condyle,

45. TEMPOROMANDIBULAR/LATERAL/CHECK
LIGAMENT
• lateral aspect of capsular ligament is
reinforced by tight fibers which make up
temporomandibular ligament
• This composed of two parts –
a. outer oblique portion
b. inner horizontal portion

46. SPHENOMANDIBULAR LIGAMENTS
• Arises from spine of sphenoid bone extends downward towards medial surface of
ramus of mandible, attaches to small bony prominence on the medial surface of
ramus called lingula
• important landmark during surgery as maxillary artery and auriculotemporal
nerve lies between it and mandibular neck

48. STYLOMANDIBULAR LIGAMENT
• This is a second accessary ligament which arises from the styloid process and
extend downward and forward to the angle and posterior border of the ramus of
the mandible
• Function
a. It becomes taut when mandible is protruded, but is most relaxed when
mandible is opened.
b. It limits excessive protrusive movement of mandible

49. MUSCLES ASSOCIATED WITH THE TMJ
• Muscles of mastication –
1. Masseter
2.Temporalis
3.Medial pterygoid
4.Lateral pterygoid

50. muscle origin fibers insertion Nerve supply action
masseter a. Superficial layer –
2/3rd of lower border
of zygomatyic arch
and zygomatic
process of maxilla
b. Deep layer –deep
surface of zygomatic
arch
c. Middle layer – lower
border of post. 1/3rd
of zygomatic arch
a. superficial-
downward and
backward
45degree
b. Deep- vertically
downward
c. Middle-
vertically
downward
Into the lateral
surface of the
ramus of the
mandible
Masseteric
nerve branch
ant. Division of
mandi. nerve
a. Elevate
mandible to
close the
mouth .
b. Superficial
fibres cause
protrusion

51. muscle origin fibres insertion Nerve supply action
temporali
s
a. Temporal
fossa
excluding the
zygomatic
bone
b. Temporal
fascia
Anterior fibers –
vertically
Middle – oblique
Posterior - horizontal
Coronoi
process
Two deep
temporal
branches from
anterior division
of mandibular
nerve .
a. Elevate the
mandible
b. Side to side
grinding
movements
c. Post. Fibres
retract the
protruded
mandible

52. muscle origin fibres insertion Nerve supply action
Lateral
pterygoi
d
a. Upper head (small) –
from infratemporal
surface and crest of
greater wing of
sphenoid
b. Lower head (larger)
from lateral surface
of lateral pterygoid
plate
Fibres run
backward
laterally and
converge
from
a. Pterygoid
fovea on
anterior
surface of the
neck of the
mandible
b. Anterior
margin of
articular disc
and capsule
TMJ
Branch from
the anterior
division of
mandibular
nerve
a. Depress
to open mouth,
with suprahyoid
muscle it is
indispensable for
opening of the
mouth
b. Protruding
mandible
c. Right lateral
pterygoid turs
chin to left

53. muscle origin fibres insertion Nerve supply action
Medial
pterygoi
d
a. Superficial head –
tuberocity of
maxilla
b. Deep head –
medial surface of
lateral pterygoid
plate
Fibers runs
downward
backward
and laterally.
Roughened area
the medial surface
of angle adjoining
ramus of mandible
below and behind
the mandibular
foramen and
mylohyoid groove
Nerve to the
medial
pterygoid
branch of main
trunk of
mandibular
nerve
a. Elevate
mandible
b. Helps protrude
the mandible
c. Right medial
pterygoid with
right lateral
pterygoid turn
the chin to left
side.

54. MUSCLES INVOLVED IN MOVEMENT.
Depression Lateral pterygoid, Digastric,
Geniohyoid,
Mylohyoid.
Elevation Temporalis, Masseter, Medial
pterygoid
Protrusion Medial pterygoid, lateral pterygoid.
Retraction Posterior fibres of temporalis.

55. BLOOD SUPPLY OF TMJ
• superficial temporal branch of external carotid
artery from posterior
• middle meningeal artery from anterior
• internal maxillary artery from inferior
• other important arteries are deep auricular,
posterior auricular and masseteric branches
of maxillary artery

56. VENOUS DRAINAGE OF TMJ
• superficial temporal vein
• maxillary plexus
• pterygoid plexus

57. NERVE SUPPLY TO TMJ
• like all joints, tmj is innervated by same nerve that
provides motor and sensory innervation to the muscles
that control it
• supplied by mandibular branch of trigeminal nerve along
with auriculotemporal, masseteric, deep temporal nerves
• it is also supplied by nonspecific articular branches of
related muscle nerves of these joint receptors of group 1-
4

58. PHYSIOLOGY OF TMJ
• What is physiology?
- it is an branch of biology which deals with the normal function of living organism or
body part.
• Physiology of TMJ includes –
- joint systems
- movement of articular disk with movement of TMJ.
- functional movements of TMJ.
- basic sgital plane position of the mandible .

59. TWO JOINT SYSTEMS ARE THERE IN TMJ
ONE JOINT SYSTEM THE SECOND SYSTEM

60. MOVEMENT OF ARTICULAR DISK WITH MOVEMENT
OF TMJ.
• The mechanism by which the disk is maintained with the translating condyle is
dependent on the morphology of the disc and the interarticular pressure.
• Three important mechanisms involved in position of disc maintaining –
1. discal ligaments
2. shape of disc
3. interarticular pressure increased, the discal space narrows, which more
positively seats the condyle on the intermediate zone

61. 1. IN RESTING CLOSED JOINT POSITION
• anterior and medial force normally exceed the posterior
elastic traction provided by superior retrodiscal lamina.
• resting closed joint position when the interarticular
pressure is low and disc space is widen .
• This relationship will be maintained during minor
passive rotational and translational movement.

62. • When the condyle is moved forward enough to cause the retractive force of the
superior retrodiscal lamina to be grater than muscle tonus force of the superior
lateral pterygoid, the disc rotate posteriorly to the extent permitted by the width
of articular space

63. • Function of lateral pterygoid during chewing –
when resistance is made during mandibular closure, such as when biting on hard
food,
the interarticular pressure on biting side decrease. This occur because the force of
closure is not applied to joint but instead applied to the food
Jaw is fulcrumed around the hard food cause in increased in interarticular pressure
in contralateral joint and sudden decrees in interarticular pressure in the ipsilateral
side
This can lead to separation of articular surfaces, resulting in dislocation. To avoid
this , superior lateral pterygoid become active during the power stroke

64. It causes rotation of the disc forwarded to the condyle .thick posterior border of the
disk maintain the articular contact and joint stability is maintained during the power
stroke of chewing.
As the teeth passes through the food the interarticular pressure is increased which
decrease the disc space and disc is mechanically rotated posteriorly so the thinner
intermediate zone fill the space.

65. FUNCTION OF LATERAL PTERYGOID DURING CHEWING –
when resistance is made during mandibular closure, such as when biting on hard
food,
the interarticular pressure on biting side decrease. This occur because the force of
closure is not applied to joint but instead applied to the food
Jaw is fulcrumed around the hard food cause in increased in interarticular pressure
in contralateral joint and sudden decrees in interarticular pressure in the ipsilateral
side

66. This can lead to separation of articular surfaces, resulting in dislocation. To avoid
this , superior lateral pterygoid become active during the power stroke
It causes rotation of the disc forwarded to the condyle .thick posterior border of the
disk maintain the articular contact and joint stability is maintained during the power
stroke of chewing.
As the teeth passes through the food the interarticular pressure is increased which
decrease the disc space and disc is mechanically rotated posteriorly so the thinner
intermediate zone fill the space.

67. FUNCTIONAL MOVEMENTS OF TMJ
• Basic movements –
1. rotation
2. translation
• Excursive movement –
1. protrusive and retrusive
2. lateral excursion
Jaw opening

68. • Border movements –
1. sagittal plane
2. horizontal plane
3. frontal plane

69. HINGE MOVEMENT –
• initial opening movement
• contraction of the inferior head of the lateral
pterygoid muscle causes the condyle to rotate on
the inferior surface of the articular disc.
• until the TM ligament become tight

70. TRANSLATION
• to open the mouth wide the condyle with the disc has
to glide/translate downward and forward across
eminence
• the superior retrodiscal lamina – increasingly stretched
– creating increase force to retract the disc
• in full forward position of mandible- retractive force on
disc by superior retrodiscal lamina is maximum.

72. JAW CLOSING
• primary action of closing movement is bilateral
contraction of the elevator muscle
• stretch is superior retrodiscal lamina created during
the opening movement , retract the articular disc,
which in turn glides posteriorly along the articular
eminence.
• lateral pterygoid with controlled relaxation provide
smooth activity.

73. HING
MOVEMENT
CLOSING
MOVEMENT
TRANSLATION
MOVEMENT

74. PROTRUSION –
• The condyle translate downward and forward in the glenoid fosssa depending on
the degree of protrusion.
• to protrude the mandible lateral and medial pterygoid muscles contraction is in
unison and in conjunction with controlled stabilizing relaxation of the opening
muscles.
• Christensen’s phenomenon and protrusive condylar guidance angle/inclination.

75. RETUSION –
• retrusion largely accompanied by contraction of posterior fibres of temporalis
muscle with some assistance from geniohyoid, digastric and mylohyoid muscles

76. LATERAL MOVEMENTS –
• working bite –This lateral movement is
initiated by combine movement of
lateral pterygoid and temporalis on one
side with controlled relaxation on the
other side
• if mandible is being moved to the right
contraction of left lateral pterygoid and
controlled relaxation of the left
temporal muscle and on the right side
there is definite contraction of the right
temporalis and controlled relaxation of
the same side lateral pterygoid.

77. • In the lateral shift of the mandible, the
working side articular disk moves toward
the side of the working bite. This is known
as the laterotrusion/mandibular lateral
translation/bennet movement
• working side - slightly laterally and rotate.
• balancing side – condyle move forward
,downward and medially.

78. • The medial movement called as mediotrusion and average path of this advancing
condyle forms an angle with the saggital plane called bennet angle or lateral
condylar guidance angle.range from 2-44 maen value 16

79. BORDER MOVEMENTS IN SAGITTAL PLANE

80. BORDER MOVEMENTS IN HORIZONTAL PLANE

81. BORDER MOVEMENTS IN FRONTAL PLANE

82. ENVELOP OF MOTION -
• This is the three dimentional combination of all the
border movements .
• It was described by Posselt.
• every tooth in mandible has its envelop on motion,
which determines outer limits to which each lower
tooth can be moved, these limits are imposed on
mandible

83. • these limits are directly related to limits imposed by ligaments, bone and muscle
on tmj
• envelop of motion can be altered by teeth that interfere with physiologic
masticatory function

84. CONCLUSION -
• Proper Anatomy and physiology of the TMJ is very important for functioning of
the temporomandibular joint. Any deviation in it may cause defect formation .
• TMJ is very important joint fro orthodontic point of view as component of TMJ
play important role during mandibular advancement procedures by functional
appliances.