TMJ Anatomy

Question 1

Which articulation forms the TMJ?

Answer 1

An articulation between the condyle of the mandible and the mandibular fossa of the temporal bone.

Question 2

What type of joint is the TMJ?

Answer 2

A synovial joint (modified hinge joint)

Articulating surfaces are lined with fibrocartilage (not hyaline as usual with synovial joints) - to withstand mastsication forces

Question 3

Describe the articular disc including its functions

Answer 3

Disc is made up of dense connective tissue with a high collagen content.

Separates the TMJ into two cavities - a superior cavity (between disc & mandibular fossa of temporal bone) and inferior cavity (between disc and mandibular condyle)

the disc;

• maximises joint congruency
• reduces contact pressure and cushions the large repetitive forces of mastication
• helps guide the gliding movement of the mandibular condyle against the temporal fossa

Question 4

What are the cavities of the TMJ?

Answer 4

Superior - between disc & temporal bone

Inferior - between disc & mandibular condyle

Question 5

What are the 3 ligaments of the TMJ?

Answer 5

Lateral / temperomandibular

• lateral to TMJ
• short and thick
• primary ligament of TMJ
• gives lateral stability & guides movemnet of condyle during mouth opening
• oblique & horizontal fibres
• both insert onto articular eminence & zygomatic arch of temporal bone
• oblique PA: neck of mandible
• horizontal PA: mandibular condyle

Sphenomandibular:

• medial to TMJ
• accessory ligament
• from spine of sphenoid to ramus of mandible

Stylomandibular:

• posterior to TMJ
• accessory ligament
• from styloid process to angle of mandible

Question 6

Describe the joint capsule of the TMJ

Answer 6

From rim of mandibular fossa
Forms collateral ligaments to attach to periphery of articular disc
And forms tendon of lateral pterygoid

Capsule is firm medially & laterally to provide stability
Capsule is lax anteriorly & posteriorly to allow movement