Introduction, Development of TMJ , Part of TMJ, Articular surfaces, Glenoid Fossa, Articular eminence, Condyle, Capsule, Articular disc, Synovial fluid, Ligaments, Blood Supply, Nerve supply, Movements of TMJ, Muscles acting on TMJ, Clinical Anatomy

1. ANATOMY OF
TEMPOROMANDIBULAR JOINT
PRESENTED BY:
DR GAYATRI MEHROTRA

2. INTRODUCTION
 TMJ is the articulation between the head of
the mandible and the mandibular fossa and
articular tubercle of the temporal bone.

3.  Also known as:
 Bicondylar joint
 Ginglymodiarthroidal joint
Provides hinging
movement in one
plane, thus
considered as
ginglymoid joint
Provides for
gliding
movements,thus
considered as
arthroidal joint
Ginglymodiarthroidal
joint

4.  It is considered as a synovial joint of the
condylar variety.
 It is classified as a compound joint because it
is made up of 3 bones:
 Anterior part of mandibular fossa and articular
tubercle of temporal bone.
 Head of the mandible.
 Articular disc ( serves as a nonossified bone ).

7. DEVELOPMENT OF TMJ
 At approximately 10 weeks the components of
future joint become evident in the mesenchyme
between the condylar cartilage of mandible and
temporal bone
 Two slitlike joint cavities and an intervening
disk make their appearance in this region by 12
weeks.
The mesenchyme around the joint begins to
form the fibrous joint capsule.

8.  Mandibular fossa is flat at birth and there is
no articular eminence, this becomes
prominent only following the eruption of the
deciduous dentition.

9.  The developing disc is highly cellular and
vascular.
 All components of the joint mature by 14th
week of gestation.
The fetal disc contains nerve fibres and blood
vessels in its periphery.
 They disappear from the disc proper but
remain at the disc attachment after birth.

10. PARTS OF TMJ
1) Articular
Surfaces
2) Glenoid Fossa
3) Articular
Eminence
4) Articular Disc
5) Capsule
6) Condyle
7) Ligaments

11. ARTICULAR SURFACES
 Upper articular surface is formed by :
 Articular eminence
 Anterior part of mandibular fossa
 The inferior articular surface is formed by the
head of mandible.

13. GLENOID FOSSA
 The glenoid or mandibular fossa is the concave
depression on the inferior surface of the petrous
part of the temporal bone.
 It is bounded posteriorly by the petrotympanic
fissure and anteriorly by the articular eminence.

14. ARTICULAR EMINENCE
 It is present anterior to the glenoid fossa.
 It is covered by dense,compact,fibrous tissue
 The fibrous covering is thickest at the
descending slope of the eminence.
 Underlying the fibrous
tissue covering is
chondroid bone
and then compact bone.

15. CONDYLE
 The adult condyle is elliptical in shape with
mediolateral width more than anteroposterior
width.
 mediolateral width= 15-20mm
 anteroposterior width= 8-10mm
 The components of the condylar covering vary
with age and with the region of the condyle.
 In the centre of the condyle, cartilage develops
and works as secondary cartilage.

16.  The cartilage contributes to enlargement of
condyle in adulthood as part of adaptive
changes in response to overloading.
 The condyle is vascular at birth and vessels
anastomose over the articular surface, but
these disappear by the age of 3 yrs.

18. CAPSULE
 The joint is surrounded by a capsule which is
attached beyond the limits of the articular
surface.
 The capsule attaches inferiorly to the priosteum
of the neck of the condyle.
 Lateral aspect attaches to the zygomatic
tubercle, lateral rim of glenoid fossa and
postglenoid tubercle.

19.  Medially, the capsule attaches to the medial
rim of the glenoid fossa.
 The articular surface of condyle is covered by
fibrocartilaginous tissue and not hyaline
cartilage.
Spine of sphenoid
Spenomandibular
ligament
Middle meningeal
artery
Closely related
to the medial
capsule

21. ARTICULAR DISC
 The articular disc is composed of dense fibrous
connective tissue , devoid of blood veesels or
nerve fibers.
 In sagittal plane,it can be divided into three
regions:
1) Intermediate zone
2) Anterior band
3) Posterior band

23.  The disc is thinnest in its center and thickens to
form anterior and posterior bands.

24.  During movements the disc is somewhat flexible
and can adapt to the functional demands of the
articular surfaces.
 The disc maintains its morphology unless
destructive forces or structural changes occur in
the joint .
 If these changes occur, the morphology of disc
can be irreversibly altered, producing
biomechanical changes during function.

25.  The articular disc is attached posteriorly to a
region of loose connective tissue that is highly
vascularized and innervated known as retrodiscal
tissue or posterior attachment.
Superior
Retrodiscal
Lamina
Inferior
Retrodiscal
Lamina

26. Articular disc
Retrodiscal
lamina
Posterior
attachment

27. Superior lamina Inferior lamina
Origin Arises from the posterior
band of the disc
Arises from the
posterior band of the
disc
Insertion It inserts to the
squamotympanic fissure
and tympanic part of the
temporal bone
Inserts into the
inferior margin of the
posterior articular
slope of the condyle
Composition Consists primarily of
elastic fibers
Consist mainly of
collagen fibers

29.  The disc and its attachment divide the joint into
upper and lower compartment.
Upper
Compartment
Passive Volume
Of Synovial
Fluid=1.2ml
Roof Is The
Mandibular Fossa
Floor Is The
Superior Surface
Of The Disc

30. Lower
Compartment
Passive Volume
Of Synovial Fluid
= 0.9ml
Roof Is Inferior
Surface Of Disc
Floor Is The
Articulating
Surface Of
Mandibular
Condyle

33. SYNOVIAL FLUID
 Joint cavity is filled with synovial fluid, thus TMJ
is referred to as synovial joint.
 Synovial fluid is a filtrate of plasma with added
mucins and proteins.
 Its main constituent is hyaluronic acid.

34.  Functions Of Synovial Fluid:
 Act as a medium for providing metabolic
requirement since the articular surfaces are
nonvascular.
 Also serves as a lubricant between articular
surfaces during function, thus helps to minimize
friction.

35.  Joint lubrication is achieved by 2 mechanisms:
1) Boundary Lubrication
2) Weeping Lubrication
Moving joint
Synovial fluid forced from one area to
other of cavity
Boundary lubrication comes into action
Prevents friction in moving joint

36. During funtion of a joint
Forces are created between articular
forces
Synovial fluid is released
Weeping lubrication comes into action
Helps eliminate friction in
compressed joint

37. HISTOLOGY OF ARTICULAR SURFACES
 The articular surfaces of the mandibular
condyle and fossa are composed of 4 distinct
layers or zones:
1) Articular
2) Proliferative
3) Fibrocartilaginous
4) Calcified cartilage

38. LIGAMENTS
The ligaments of the joint are made up of
collagenous connective tissues.
 If extensive forces are applied the ligament
can be elongated altering the joint function.
 3 functional ligaments:
1) The collateral ligament
2) The capsular ligament
3) The temporomandibular ligament(lateral
ligament)

39.  There are also two accessory ligaments:
1) The sphenomandibular ligament
2) The stylomandibular ligament

40.  The Collateral Ligament:
 These ligaments attach the medial and lateral
borders of the articular disc to the poles of the
condyle
 Commonly called discal ligaments
1) medial discal ligament
2) lateral discal ligament

41.  Collateral ligaments are true ligaments and do
not stretch.
 They are responsible for the hinging
movement of the tmj.
 The Capsular Ligament:
 The entire TMJ is surrounded and
encompassed by the capsular ligament.
 Superiorly, it is attached to margins of
Articular disc and Articular fossa.

42.  Inferiorly, it is attached to the neck of the
condyle.
 A significant function of the capsular ligament
is to encompass the joint, thus retaining the
synovial fluid.

43.  The Temporomandibular Ligament Or Lateral
Ligament:
 The lateral aspect of the capsular ligament is
reinforced by strong,tight fibers that make up
TM ligament.
IHP = Inner Horizontal
Portion
OOP= Outer Oblique
Portion

44.  Attached above to the tubercle of the root of
the zygoma.
 Below to the lateral surface and posterior
border of the neck of mandible.

46. Force is applied to mandible
Inner horizontal portion of ligament becomes tight
Prevents the condyle from moving into posterior region
of mandibular fossa
Thus, protects the retrodiscal tissues from trauma
Also, protects lateral pterygoid muscle from over-
lengthening or extension

47.  The Sphenomandibular Ligament:
 It is one of the accessory ligament.
 Attached above to the spine of sphenoid.
 Below to the lingula of the mandible.

48.  The Stylomandibular Ligament:
 It is the thickened part of the deep part of the
capsule of the parotid gland derived from deep
cervical fascia.
 Attached above to the styloid process of
temporal bone.
 Below to the angle of mandible and adjacent
part of the posterior part of the ramus of
mandible.

49.  It limits the excessive protrusive movements
of the mandible.

50. RELATIONS OF TMJ

51. BLOOD SUPPLY
 TMJ is richly supplied by a variety of vessels
that surround it.
Includes following:
1) Superficial Temporal Artery from posterior
2) Middle Meningeal Artery from anterior
3) Internal Maxillary Artery from inferior

53.  Other important arteries are:
1) Deep auricular artery
2) Anterior tympanic artery
3) Ascending pharyngeal artery
 Condyle receives its vascular supply through
its marrow spaces by way of inferior alveolar
artery and “feeder vessels” that enter directly
into condylar head.

55. NERVE SUPPLY
 TMJ is innervated by the Trigeminal Nerve that
provides sensory and motor innervation to
muscles that control it.
 Branches of mandibular nerve
 Auriculotemporal nerve
 Deep temporal nerve
 Masseteric nerves

57. MOVEMENTS OF TMJ
 Protraction of mandible:
 The articular disc glides forward over the upper
articular surface, the head of the mandible
moving with it.
 Retraction of mandible:
 Reversal of protraction.

58.  Depression of mandible:
 The head of mandible moves on the
undersurface of the disc like a hinge.
 In wide opening, this hinge like movement is
followed by gliding of the disc and the head of
mandible.
 Elevation of mandible:
 The movements are reversed in this as they
were in depression of mandible.

59.  Side to side movements:
 Head of one side glides forward along with
the disc as in protraction, but the head of
other side rotates on a vertical axis.

61. MUSCLES ACTING ON TMJ
1) Depression:
 Lateral pterygoid
 Platysma
 Mylohyoid
 Geniohyoid
 Anterior belly of digastric

62. 2) Elevation:
 Temporalis
 Masseter
 Medial pterygoid
3) Protraction:
 Medial pterygoid
 Lateral pterygoid
 Superficial fibres of the
masseter

63. 4) Retraction:
 Temporalis posterior horizontal fibres
 Masseter deep fibres
5) Side to side:
 Medial pterygoid
 Lateral pterygoid

65. CLINICAL ANATOMY
 Dislocation Of Mandible:
 During excessive opening of mouth or during a
convulsion, the head of the mandible of one or
more sides may slip anteriorly into the
infratemporal fossa, as a result of which there is
inability to close the mouth.
 Reduction is done by depressing the jaw with
the thumbs placed on the last molar, and at the
same time elevating the chin.

67.  Deflection And Deviation Of Mandible:
The difference between deviation and
deflection is represented by the deviated joint
returns to center and the deflected TMJ stays to
one side.

68.  Derangement Of The Articular Disc:
 It may result from any injury like overclosure or
malocclusion.
This give rise to clicking and pain during
movements of the jaw.

71.  Trismus:
 It is defined as a prolonged , tetanic spasm of
the jaw muscles by which normal opening of
the mouth is restricted (locked jaw).
 Causes :
 Infection
 Trauma
 Tetany
 Tetanus
 Neurological disorders
 Drug induced

72.  Ankylosis:
 Ankylosis means abnormal immobility of a
joint.
 Causes:
 Trauma
 Infection
 Autoimmunedisease
 Long standing
immobilization

73.  Jaw Jerk Reflex And Jaw Opening Reflex:

74.  In Operations On The Joint, the seventh cranial
nerve that is facial nerve should be preserved
with care.

75. REFERENCES
 Management Of Temporomandibular
Disorders And Occlusion- 5 Edition- By Jeffrey
P. Okeson
 B D Chaurasia Human Anatomy- 4 Edition-
Vol3
 Principles Of Anatomy And Oral Anatomy- By
M.E.Alkinson And F.H.White
 Human Anatomy For Dental Students-2
Edition By M V Ramasay
 Burkets Oral Medicine-11 Edition-by
Greenberg And Glick And Ship

76.  Textbook Of Oral And Maxillofacial Surgery-by
S M Balaji
 Textbook Of Oral And Maxillofacial Surgery- 2
Edition- Neelima Anil Malik

77. QUESTIONS
 Ligaments of tmj?
 Movements of tmj?
 Tmj capsule is formed by?
Muscle acting on Tmj?

78.  Various projections for imaging tmj?
 Other names for tmj?
 Nerve supply for tmj?