The following seminar cover anatomy, attachment and biomechanics of TMJ (Contains 2 video inside).

1. Anatomy of TMJ &
its applied
anatomy
Prepared by: Vishal Trivedi
Guided by : Dr. Mrugnayani Patel

2. Contents
Introduction
Development of TMJ
Anatomy of TMJ
Vascularization and Innervations
Biomechanics of TMJ

3. Temporomandibular Joint
 Connects the jaw bone to the skull.
 It is a Compound, Synovial,
Ginglymo diarthroidal joint.
 It's the articulation between the
squamous portion of the temporal
bone and the condyle of the
mandible.

4. Compound Joint
 Functionally, articular disc serves as a non ossified bone
which permits complex movement of joint

5. Ginglymo
diarthroidal
Ginglymoid Hinging
Arthodial Gliding

6. Development of TMJ
 Last joint to start its development, in about 7th week in utero.
 Meckel's cartilage provides skeletal support.
 Development of TMJ begins with condensation of the developing
mesenchymal matrix around the Meckel's cartilage - 6th to 7th week of IU.

7. Embryonic development of TMJ
Blastemic
stage
(7-8 wks IU)
Cavitation
stage
(9-11 wks IU)
Maturation
stage
(12th week IU)

8.  Temporal blastema forms articular surface of temporal bone.
 Condylar blastema forms condylar cartilage, aponeurosis of lateral
pterygoid muscle, articular disc & TMJ capsule.
 Inferior joint space is formed by cavitations that develops between the
condylar blastema & the mesenchymal connecting band of Meckel's
cartilage.
 Superior joint space is formed by cavitation between fibrous band &
articular fossa.
 Condylar process of mandible develops by endochondral ossification.
 Glenoid fossa & articular eminence form by intra membranous ossification.

9. Anatomy of TMJ
TMJ
Articular
surface
Articular Disc Ligament

10. Articular surface
Cranial
Component
Articular
Eminence
Articular Tubercle
Entoglenoid
process
Lateral border of
mandibular fossa
Posterior auricular
ridge and post
glenoid process
Preglenoid plate
Mandibular
Component

12. Histology of TMJ
 Fibrocartilaginous covering of condyle is composed of 4
layers :-
Articular layer
Proliferative layer
Fibrocartilaginous zone
Calcified cartilage zone

13. Articular zone
1)Dense fibrous
connective tissue
2)Collagen fibres
arranged parallel
to articular surface
3)Better
ability to repair.
Proliferative zone
1) Mainly cellular
zone.
2) Undifferentiated
mesenchymal cells.
3) Proliferation
&regeneration
throughout life.
Fibrocartilaginous
zone
1) Crossing pattern
of bundles.
2) Providing a three-
dimensional network
that offers resistance
against compressive
and lateral forces.
Calcified cartilage
zone
1) Deepest zone.
2) Chondrocytes ,
chondroblasts
3) Extracellular matrix
scaffolding provides an
active site for
remodeling activity

14. Articular disc
 Composed of dense fibrous connective
tissue
 In sagittal plane it is divided into 3 regions
according to thickness
1. Intermediate zone : thinnest part
2. Posterior border : thickest part
3. Anterior border
 Articular surface of condyle is located on the
intermediate zone.

15. SC – Superior Joint cavity IRL – Inferior Retro discal lamina
IC - Inferior Joint cavity SC – Superio Joint cavity
RT – Retrodiscal tissues ACL – Anterior Capsular ligament
SRL – Superior Retro discal lamina

16. The Superior and Inferior
attachments of the anterior
region of the disc are to the
capsular ligament
 Superior attachment : articular surface of
the temporal bone
 Inferior attachment : articular surface of the
condyle
 Both attachments are composed of
collagenous fibres.

17. The articular disc is attached posteriorly to a region
of loose connective tissue which is known as
Retrodiscal tissue.
Highly vascularized and innervated
Superiorly : Superior retrodiscal lamina
Inferiorly : Inferior retrodiscal lamina

18. The articular disc is also attached to the capsular
ligament on medially and laterally which divides the
joint cavity into upper and lower cavity
Upper cavity is bordered by mandibular fossa and superior
surface of the disc.
Lower cavity is bordered by the mandibular condyle and
inferior surface of the disc.

19. Synovial Joint
 Synovial – Freely movable
 Synovial fluid :-
 1) Acts as a medium for providing metabolic requirements.
 2) It also serves as lubricant which helps to minimize friction
between articular surfaces.

20. Synovial fluid lubricates the articular
surfaces two mechanisms
1. Boundary lubrication
2. Weeping lubrication

21. Boundary lubrication
Primary mechanism of joint lubrication.
occurs when the joint is moved and the synovial fluid is
forced from one area of the cavity into another.
Synovial fluid is located in the border or recess area.
Prevents friction in the moving joint.

22. Weeping lubrication :
Refers to the ability of the articular surfaces to absorb
a small amount of synovial fluid.
During function of a joint, forces are created between
the articular surfaces. These forces drive a small
amount of synovial fluid in and out of the articular
tissues.
By this mechanism metabolic exchange occurs.
Helps eliminate friction in the compressed but not
moving joint.

23. Ligaments
 Ligaments are made up of collagenous connective tissue
fibers that have particular lengths.
 Do not stretch
 Ligaments do not enter actively into joint function but instead
act as passive restraining devices to limit and restrict border
movements.

24. Ligaments of
TMJ
Functional
ligaments
Collateral
ligaments
Capsular
ligament
Temporomandibula
r ligament
Accessory
ligaments
Sphenomandibular
ligament
Stylomandibular
ligament

25. Collateral Ligament
 Also known as Discal
Ligament.
 True ligaments - composed
of collagenous connective
tissue fibers therefore they
do not stretch.
 Collateral ligaments attach
the medial and lateral
borders of the articular disc
to the poles of the condyle.

26.  Divide the joint mediolaterally into the superior and inferior
joint cavities.
 Functions:-
 To restrict movement of the disc away from the condyle.
 Responsible for the hinging movement of the TMJ.

27. Capsular ligament
 TMJ is surrounded and
encompassed by the
capsular ligament
 Fibres of capsular ligament
are attached
 Superiorly : to the
temporal bone, borders
of the articular surfaces
of the mandibular fossa
and articular eminence
 Inferiorly : to the neck of
the condyle

28. Functions :
To resist any medial, lateral, or inferior forces that tend to
separate or dislocate the articular surfaces.
Retaining the synovial fluid by encompassing the joint.
Provides proprioceptive feedback regarding position and
movement of the joint.

29. Temporomandibular ligament
 Also known as lateral
ligament.
 Lateral aspect of the capsular
ligament is reinforced by
strong, tight fibers that make
up the temporomandibular
ligament .
 Composed of two parts :
Outer oblique portion
Inner horizontal portion

30. Outer oblique portion
 Origin :- extends
from the outer
surface of the
articular tubercle
and zygomatic
process
posteroinferiorly
 Insertion :- outer
surface of the
condylar neck

31. Functions
 Resists excessive dropping of the condyle, therefore limiting the extent
of mouth opening.
 Influences the normal opening movement of the mandible.
 When the ligament is taut, the neck of the condyle cannot rotate further
 The jaw will easily rotate open until the anterior teeth are 20 to 25 mm
apart.
 This limitation of rotational opening is unique feature of TM ligament.

33. The Inner horizontal portion
 Origin : extends from the outer surface of
the articular tubercle and zygomatic
process
 Insertion : lateral pole of the condyle and
posterior part of the articular disc
 Functions :
 force applied to the mandible displaces the
condyle posteriorly, this portion of the
ligament becomes tight and prevents the
condyle from moving into the posterior
region of the mandibular fossa therefore
protects the retrodiscal tissues from
trauma.
 Protects the lateral pterygoid muscle from
overlengthening or extension.

34. Accessory Ligaments

35. Accessory ligament
Sphenomandibular ligament
• Arises from the spine of the
sphenoid bone and extends
downward to lingula
• Does not have any significant
limiting effects on mandibular
movement.
Stylomandibular ligament
• Arises from the styloid process
and extends downward and
forward to the angle and
posterior border of the ramus of
the mandible
• Becomes taut when the
mandible is protruded, but is
most relaxed when the mandible
is opened
• Limits excessive protrusive
movements of the mandible

36. Innervation of the TMJ
 Innervated by Mandibular division (V3) of the trigeminal
nerve.
 Three branches from the mandibular nerve send terminals to
the joint capsule.
 The largest is the auriculotemporal nerve which supplies the
posterior, medial and lateral aspects of the joint.
 Massetric nerve
 A branch from the posterior deep temporal nerve, supply the
anterior parts of the joint.

37. Vascularization of the TMJ
 Anterior : Middle meningeal artery
 Posterior : Superficial temporal artery
 Inferior : Internal maxillary artery
 TMJ is also supplied by deep auricular, anterior tympanic, and
ascending pharyngeal arteries.
 Condyle receives its vascular supply from inferior alveolar
artery.

39. Biomechanics of the
Temporomandibular Joint

40.  Structure and function of TMJ can be divided into two
distinct systems:
 Tissues that surround inferior synovial cavity :
Disc is tightly bound to the condyle by the lateral and medial
discal ligaments.
Responsible for rotation of the disc.
 Condyle-disc complex functioning against the surface of the
mandibular fossa :
Responsible for translatory movement.

41.  Stability of the joint is maintained by constant activity of the
muscles that pull across the joint, primarily the elevators.
 Even in the resting state, these muscles are in a mild state of
contraction called “tonus” .
 As muscle activity increases, the condyle is increasingly
forced against the disc and the disc against the fossa,
resulting in an increase in the interarticular pressure.

42.  When the pressure is low, the disc space widens slightly, a
thicker portion of the disc is rotated to fill the space.
 When the pressure is high, as during clenching of the teeth,
the disc space narrows, the condyle seats itself on the thinner
intermediate zone of the disc.

43.  Posterior border of the articular disc is attached to the the
retrodiscal tissues.
 In the closed mouth position superior retrodiscal tissue is
somewhat folded over itself.
 During mandibular opening, when the condyle is pulled
forward down the articular eminence, the superior retrodiscal
lamina becomes increasingly stretched, creating increased
forces to retract the disc.
 As the mandible moves into a full forward position and during
its return, the retraction force of the superior retrodiscal
lamina holds the disc rotated as far posteriorly on the condyle.

44. Function of Lateral Pterygoid
 Anterior border of the articular disc is attached to the the
superior lateral pterygoid muscle
 When this muscle is active, the fibers that are attached to the
disc will pull the disc anteriorly and medially. Therefore it is a
protractor of the disc
 Protraction of the disc does not occur during jaw opening

45.  When the inferior lateral pterygoid is protracting the condyle
forward, the superior lateral pterygoid is inactive and therefore
does not bring the disc forward with the condyle.
 The superior lateral pterygoid is activated only in conjunction
with activity of the elevator muscles during mandibular closure
or a Power stroke.

46.  During translation, the combination of disc morphology and
interarticular pressure maintains the condyle on the intermediate
zone and the disc is forced to translate forward with the condyle.
 Proper morphology plus interarticular pressure results in an
important self-positioning feature of the disc.
 Only when the morphology of the disc has been greatly altered
does the ligamentous attachment of the disc affect joint function.

49. References
 Management of temporomandibular joint disorders and
occlusion, 8th edition, by Jeffrey P. Okeson
 Gray’s anatomy, The Anatomical Basis of Clinical Practice ,
41st edition
 Human Embryology, 8th Edition, Inderbirsingh
 Anatomy of the Temporomandibular JointX. Alomar, MD,* J.
Medrano, MD,† J. Cabratosa, MD,† J.A. Clavero, MD,* M.
Lorente, MD,‡I. Serra, MD,§ J.M. Monill, MD,* and A.
Salvador, MD*

50. Thank You !