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1. TOPIC
BIOMECHANICS OF
TEMPOROMANDIBULAR JOINT

2. PURPOSE
To Give Important Information
About How Temporomandibular
Joint Works And How To
Appreciate It In Clinical Practice

3. Biomechanics Of
Temporomandibular Joint
Part I
Introduction to
Temporomandibular Joint

4. Biomechanics of Temporomandibular
Joint
Part 1 : Introduction to Temporomandibuular Joint
What is Temporomandibular
joint?

5. What is Temporomandibular Joint?
The Temporomandibular Joint (TMJ) Is The Joint Of
The Jaw
www.wikipedia.com

6. What is Temporomandibular Joint?
The name is derived from the two bones which form
the Joint : The temporal bone and the Mandible
Temporal Bone
Mandible
www.wikipedia.com

7. What is Temporomandibular Joint?
There are two TMJs, one on each side, working in
unison.
www.wikipedia.com

8. Biomechanics of Temporomandibular
Joint
Part 1 : Introduction to Temporomandibuular Joint
Differences between
Temporomandibular Joint &
other joints in the body

9. Differences between TMJ & Other
Joints in the Body
1.TMJ has an articular disc which compeletely divides
the joint spaces into upper and lower joint
compartements.
Two Joints are connected
Superior Joint Cavity
Articular Disc
Inferior Joint Cavity
TMJ
Famona.tripod.com

10. Differences between TMJ & Other
Joints in the Body
2.TMJ is a ginglymoarthrodial joint
• Hinge Action (Rotation)
• Slide Action (translation)
Famona.tripod.com

11. Differences between TMJ & Other
Joints in the Body
3. Relationship of teeth affects the
relationship of the articulating components.
Famona.tripod.com

12. Differences between TMJ & Other
Joints in the Body
4. The mandible is the only bone in the body
hinged on both ends that is not capable of
independent movement at one end.
Famona.tripod.com

13. Biomechanics Of
Temporomandibular Joint
Part 2
Introduction to the
Biomechanics of TMJ

14. Biomechanics of
Temporomandibular Joint
Part 2 : Introduction to the Biomechanics of TMJ
Definition Of
Biomechanics

15. ?
Biomechanics is the study of the
structure and function of biological
systems
www.wikipedia.com

16. Biomechanics of
Temporomandibular Joint
Part 2 : Introduction to the Biomechanics of TMJ
Biomechanics of TMJ

17. ?
Biomechanics of
Temporomandibular Joint is a
complex combination activity
Both the left and right joints must
function together in the coordination
of jaw movement
Okeson, 2008

18. ?
Fossa
Articular disc
Condyle
Okeson, 2008

19. Biomechanics Of
Temporomandibular Joint
Part 3
The Joint System

20. BIOMECHANICS OF THE
TEMPOROMANDIBULAR JOINT
Part 3 : The Joint System
One Joint System

21. One Joint System
Tissues that surrounds the inferior synovial
cavity
Articular disc
Condyle
Inferior
synovial cavity
Okeson, 2008

22. One Joint System
Rotation is the only physiologic movement
that can occur between the surfaces
Rotation in the TMJ usually occurs only
during the opening the mouth 20 – 25 mm
Okeson, 2008

23. The condyle is not
sliding out of the fossa
so, only one joint
system is involved =
Rotation Movement
Okeson, 2008

24. BIOMECHANICS OF THE
TEMPOROMANDIBULAR JOINT
Part 3 : The Joint System
Second Joint System

25. Second Joint System
Free sliding movement of the disc between the
surface in the superior cavity, referred to as
translation.
Superior Fossa
synovial cavity
Articular disc
Okeson, 2008

26. Translation occurs when the mouth opening is
more than 25 mm.
Okeson, 2008

27. The condyle slides out of
the fossa to the articular
eminence
so, not only one joint
system is involved =
Translation Movement
Okeson, 2008

28. Biomechanics Of
Temporomandibular Joint
Part 4
Articular Disc

29. BIOMECHANICS OF THE
TEMPOROMANDIBULAR JOINT
Part 4 : Articular Disc
?
Function
Importance

30. BIOMECHANICS OF THE
TEMPOROMANDIBULAR JOINT
Part 4 : Articular Disc
?

31. ?
The articular disc is a fibrous extension of
the capsule in between the two bones of
the joint.
www.wikipedia.com

32. BIOMECHANICS OF THE
TEMPOROMANDIBULAR JOINT
Part 4 : Articular Disc
Function

33. Function
1. Acts as a cushion to absorb stress
2. Isolate synovial fluid
Okeson, 2008

34. Function
3. Divide a joint cavity
• Upper & Lower compartments
Superior Joint Cavity
Inferior Joint Cavity
Okeson, 2008

35. Function
4. Determinant of joint movement
Rotation Translation
Okeson, 2008

36. BIOMECHANICS OF THE
TEMPOROMANDIBULAR JOINT
Part 4 : Articular Disc
Importance

37. The Importance
The spasm in the masticatory muscles is a
direct cause of pressure on the articular
disc inside TMJ
If the disc slips out of place or is displaced, it
can prevent the proper movement of the
condyle and cause dysfunction.
Okeson, 2008

38. Biomechanics Of
Temporomandibular Joint
Part 5
Stability Of The Joint

39. BIOMECHANICS OF THE
TEMPOROMANDIBULAR JOINT
Part 5 : Stability of the Joint
Anatomic structures
Constant activity of the muscle
The ligaments
Interarticular Pressure

40. BIOMECHANICS OF THE
TEMPOROMANDIBULAR JOINT
Part 5 : Stability of the Joint
Anatomic structures

41. Anatomic Structures
Every joint in the human body has anatomic
structures which impart stability during function.
These structures are :
1. The osseous conformation of the
articulating ends of the bones of the
joints
2.Muscle which activate joint and
stabilize the joint
Okeson, 2008

42. Anatomic Structures
Every joint in the human body has anatomic
structures which impart stability during function.
These structures are :
3. Ligaments which help stabilize
the joint by limiting movement
4.Capsule and disc which form a
part of a joint
Okeson, 2008

43. BIOMECHANICS OF THE
TEMPOROMANDIBULAR JOINT
Part 5 : Stability of the Joint
Constant activity of the muscle

44. Constant Activity of the muscles
Stability is maintained
by constant activity of
the muscles that pull
accross the joint
Elevator muscles
• Masseter
• Temporalis
• Medial pterygoid
Okeson, 2008

45. Constant Activity of the muscles
In the resting state, these muscles are in
a mild state of contraction called tonus.
Okeson, 2008

46. BIOMECHANICS OF THE
TEMPOROMANDIBULAR JOINT
Part 5 : Stability of the Joint
The ligaments

47. The Ligaments
Stabilize the joint by limiting
movement
Ligaments do not stretch but
it could be elongated
Elongation of Ligaments could
compromise normal joint function
Okeson, 2008

48. BIOMECHANICS OF THE
TEMPOROMANDIBULAR JOINT
Part 5 : Stability of the Joint
Interarticular Pressure

49. Interarticular Pressure
The pressure between the articular surfaces
of the eminence and the condyle
The Absence of Interarticular pressure will
cause the separation of articular surfaces
and the joint will technically dislocate
Okeson, 2008

50. Biomechanics Of
Temporomandibular Joint
Part 6
Normal Fuctional movement
of Condyle and disc

51. BIOMECHANICS OF THE
TEMPOROMANDIBULAR JOINT
Part 7 : Normal Functional movement of the
condyle and disc
Supporting Structures
Opening
Closing

52. BIOMECHANICS OF THE
TEMPOROMANDIBULAR JOINT
Part 7 : Normal Functional movement of the
condyle and disc
Supporting Structures

53. Supporting Structures
Fossa
Articular disc
Condyle
Superior
Lateral
Retrodiscal Pterygoid
Lamina
Inferior Lateral
Pterygoid
Okeson, 2008

54. BIOMECHANICS OF THE
TEMPOROMANDIBULAR JOINT
Part 7 : Normal Functional movement of the
condyle and disc
Opening

55. OPENING
During
Opening, Superior
Lateral Pterygoid
is not contracting
Inferior lateral
Superior
pterygoid is
retrodiscal
contracting –
lamina
Pulls the head of
stretches &
condyle forward
Rotates the
disc
posteriorly
Okeson, 2008

56. BIOMECHANICS OF THE
TEMPOROMANDIBULAR JOINT
Part 7 : Part 7 : Normal Functional movement of
the condyle and disc
Closing

57. CLOSING
Opposes the force of
retrodiscal lamina Superior lateral
pterygoid pulls the
disc anteriorly
Okeson, 2008

58. Conclusion :
As a clinician, please be familiar with
the structures and function of the
temporomandibular joint.