1. TMJ

2. TMJ?

3. TEMPOROMANDIBULAR JOINT

4. The only joint in the head?

5. No

6. Type of the joint?

7. Synovial

8. Bone
Muscle
Ligaments
Innervation
Function

9. LEARNING OBJECTIVE Describe the anatomical structures of the joint
Explain the articulating surfaces of the bones
Describe the embryology of the joint
Identify: capsule, synovial membrane, ligament and articulating disc
Describe the muscles and the movements that take place in the joint
Describe the nerve and blood supply to the joint
Explain how dislocation of the joint can occur

10. TMJ Joint/ articulation?
Connection between two separate parts of skeleton
Mandible and the two temporal bones
Craniomandibular joint
Bilateral articulation
the only visible movable joint in the head

11. Exercise
Palpate the TMJ

12. Three articulating parts:
Articular eminence (or tubercle)
Articular fossae
Mandibular condyle
Enclosed by fibrous connective tissue capsule

15. Mandibular condyle
Surface covered by thickened layer of fibrous connective tissue

17. Articular fossa and articular eminence
Articular fossa – non functioning portion
Articular eminence
functioning portion
Just anterior to the articular fossa
Lined by thicker layer of fibrous tissue

19. Articular disc Tough oval pad of dense ficrous connective tissue
Surface – smooth
Thinner in the centre than around the edges
Concave anteriorly to fit under the articular eminence
Convex posteriorly to conform to the shape of articular fossa
Flattened disc  problems

20. Articular disc Function:
Partitioning the complex condylar movement into upper and lower functional components
Lubricating with synovial fluid
Stabilising condyle
Cushioning the loading
Reducing physical wear and strains
Helping regulate movements of the condyle

22. How does TMJ differ from other synovial joints?
TMJ develops between 8 – 14 weeks compared to 5-8 weeks for other synovial joints
TMJ – initially widely separated temporal and condylar blastema that grow towards each other
Limb joint develops to adulthood by cavity fromation within single blastema
Fibrous cartilagerather than hyaline cartilage

23. Embryology
10 – 12 weeks pc
Ossification of the temporal components begins independently of the events in the mandible
the condylar cartilage is present at the most superior aspect of the ramus.
the embryonic connective tissue (mesenchyme) between the growing condyle and temporal bone condenses to form the articular disc
Inferior compartment form first (10 weeks) , upper (11.5)
cavitation forms the lower joint compartment and then the upper compartment

24. 14 weeks
Joint development completed

25. Development Infants: During development
Articular fossa, articular eminence and condyle – flat
About the same level as occlusal plane
Why?
During development
Articular fossa deepens
Articular eminence - > prominent – when?
Condyle becomes rounded

26. Accelerates until 12th year of life
Growth
Structure grow laterally – widening of the neurocranium
Mature disc – changes shape, more compact, less cellular, more collagen
Condyle contains cartilage
After eruption of permanent dentition, articular tubercle becomes prominent
Accelerates until 12th year of life

27. Fibrous capsule Sheet/sac/tube of tissue Encloses the joint
Fairly thin
Lateral – temporomandibular ligament
Attachment – upper – circumference of articular fossa
Lower – neck of the condyle

28. Two layers: Inner layer (synovial membrane) Outer layer
Lines fibrous capsule
Covers the bone
Secretes synovia – lubricates and nourishes
Outer layer
Thicker layer of fibrous tissue
Accessory ligaments

30. Ligaments Capsular ligament – restricts posterior movement of condyle
Temporomandibular ligament
Attachment – upper – zygoma arch, lower – side and back of condyle neck
keeps condyle close to the fossa
Helps prevent lateral and posterior displacement
Stylomandibular ligament
Posterior to the joint
Attached at the _____ and _____
Sphenomandibular ligament
Medial to the joint
Limit maximum opening
Attached to ______ and _______

32. Articular disc Dense fibrous connective tissue
Between mandibular condyle and articular fossa/eminence
Thinner – center
Anteriorly and laterally
Act as a buffer

33. Muscles Muscles of mastication Masseter Temporalis Medial pterygoid
Lateral pterygoid

34. Masseter Most superficial, powerful Quadrilateral
Origin: Zygomatic arch – inferior and medial surface and temporal process of zygomatic bone
Insertion: lateral surface of the ramus
Function: closes jaw, crushing

35. Temporalis muscle Fan shaped, large but flat muscle
Origin: entire temporalis fossa (part of frontal and parietal bone, squamous part of temporal and greater wing of sphenoid)
Directed downward (anterior), downward, anteriorly (posterior part) – passing medial to zygomatic arch
Insertion: coronoid process, anterior border of ramus and temporal crest
Action: elevator, retractor

36. Medial pterygoid Medial to ramus
Origin: medial surface of lateral pterygoid plate and pterygoid fossa, pyramidal process of palatine bone
Pass downward, laterally towards the angle of mandible
Insertion: medial surface of mandible in triangular region
Action: elevator

37. Lateral pterygoid Horizontal fibres Short, thick
Located in the infratemporal fossa
Prime mover of mandible except closing
Origin: 2 heads – upper head – infratemporal surface on great wing of sphenoid
Lower head – lateral side of pterygoid plate on sphenoid bone
Insertion: upper head – neck of condyle and anteroposterior surface of capsular ligament, into disc
Lower head – roughened pterygoid fovea on anterior surface of neck of condyle

38. Action: opening the jaw
Pulling articular disc and condyle forward down onto articular eminence

40. Innervation Proprioceptive neurons in capsule and disc
Trigeminal nerve (cranial nerve V) – auriculotemporal branch of ______
Branches of mandibular division of the TN (auriculotemporal, deep temporal and masseteric) supply the joint

41. Blood supply branches of external carotid artery
Ascending pharyngeal and superficial temporal branches
Anterior tympanic
Massteric
Middle meningeal branch of maxillary artery -

43. Stuck in front of articular eminence
Problem
Dislocation
Extreme opening of the jaw – laughing, dental treatment
Condyle moves too far
Stuck in front of articular eminence
Muscle spasm

45. RECAP

46. Name the bony components of TMJ?
Muscles that close the jaw
Nerve innervate the joint