Oral Biology: TMJ Flashcards
What type of joint is the TMJ?
Synovial
Between which two bones is the TMJ located?
Temporal and Mandible
The TMJ is capable of hinge and slide movements. What other name is given to a joint that is capable of such movements?
A glinglymoarthroidal joint
The TMJ is a unique joint due to it’s 2-compartment joint space - disc. What two things limit it’s movement?
1) The contralateral TMJ
2) Teeth
Which fossa of the skull does the condyle of the mandible sit in?
The glenoid fossa (of the temporal bone)
What is the structure anterior to the glenoid fossa called?
The articular eminence
Which two structures bind in the glenoid fossa?
1) the articular eminence
2) tympanic plate of the temporal bone
Is the glenoid fossa thin bone or thick bone?
The glenoid fossa is thin bone - masticatory forces are transmitted through teeth
What lies anterior to the external acoustic meatus?
The glenoid fossa
How would you describe the condyle? (4)
1) Much variation in shape
2) Usually oval in outline
3) Medial aspect is wider than Lateral aspect
4) Lateral Pole anterior to Medial Pole
What type of cartilage does the condyle have on it’s surface?
Fibrous cartilage
Describe the Joint Capsule of the TMJ (4)
1) Thin
2) Attached to the Glenoid Fossa
3) Continuous with Disc
4) Has two layers: outer fibrous layer and inner synovial membrane
Describe the inner synovial membrane of the joint capsule of the TMJ
1) inner aspect of the joint capsule
2) secretes synovial fluid to fill joint spaces
What is the synovial fluid in the inner synovial membrane comprised of? (3)
1) proteoglycans
2) lubricant
3) nutritive
Describe the Lateral Ligament (2)
1) essentially part of the joint capsule
2) spans from the lateral surface of the articular eminence to the posterior surface of the condyle
What is the function of the Lateral Ligament?
1) restricts posterior, lateral and inferior movement
2) restricts contralateral medial movement
3) limits the extent of a pure hinge movement
Name the three accessory ligaments of the TMJ
1) Stylomandibular Ligament
2) Pterygomandibular Raphe
3) Sphenomandibular Ligament
What are the 5 zones of the articular disc?
1) anterior extension
2) posterior extension
3) anterior band of disc
4) intermediate zone of disc
5) posterior band of disc
What is the articular disc?
The articular disc is a dense, fibrous disc which transmits forces, protects and lubricates the articulating surfaces of the TMJ
How many compartments does the articular disc divide into and what are their movements?
The articular disc divides into two compartments:
1) Upper - facilitates slide movements
2) Lower - facilitates hinge movements
Describe the two parts of the posterior extension of the articular disc
1) upper layer - vascular and elastin (elastin fibres)
2) lower layer - fibrous
Both layers are densely innervated and vascular
Which muscle is the anterior extension of the articular disc continuous with?
The anterior extension is continuous with the superior head of the lateral pterygoid muscle
Which cranial nerve supplies the TMJ?
The mandibular division of the trigeminal nerve (CNVc) supplies the TMJ
Which part of the TMJ is richly innervated, and which is not?
The joint capsule of the TMJ is richly innervated, but the disc is not.
Which two arteries supply the TMJ with blood?
1) superficial temporal artery
2) maxillary artery
Nerve endings in the TMJ:
What do the free nerve endings in the TMJ bring about?
What do the complex nerve endings in the TMJ bring about?
1) FREE NERVE ENDINGS - bring about nociception (the sensation of pain)
2) COMPLEX NERVE ENDINGS - bring about awareness of movement/posture/position
What movement occurs with slight jaw opening?
A simple hinge movement resulting in lower joint space
What movements occur with a wide jaw opening?
Hinge and slide movements resulting in an upper joint space between the condyle and the glenoid fossa
What movements occur with protrusion of the mandible?
The condyle slides anteriorly leaving an upper joint space between the condyle and the glenoid fossa
Describe the bilateral movements of the TMJ when a patient moves their jaw to the right?
Left TMJ: translates laterally
Right TMJ: rotates around vertical axis and therefore moves laterally to the right
Describe the bilateral movements of the TMJ when a patient moves their jaw to the left?
Right TMJ: translates laterally
Left TMJ: rotates around vertical axis and therefore moves laterally to the left
What kind of displacement can cause pain/problems in the TMJ?
Anterior disc displacement
What kind of displacement causes clicking of the TMJ?
Anterior disc displacement with reduction
Anatomically describe the dislocation of the TMJ and its resulting effect on the muscles
A TMJ dislocation is when the condyle is anterior to the articular eminence. it causes surrounding muscles spasm.
