TEMPOROMANDIBULAR JOINT

Question 1

classification

Answer 1

1. modified synovial hinge joint
2. atypical synovial joint as the joint consists mainly of collagen fibres with few cartilage cells and no hyaline cartilage
3. both bones are covered by a layer of fibrocartilage which is identical in composition to the disc

Question 2

TMJ permits

Answer 2

1. gliding- translational
2. small degree rotation- pivoting
3. flexing - elevation
4. extension- depression

Question 3

fibrocartilaginous disc

Answer 3

separates TMJ into upper and lower cavities

Question 4

TMJ articulation surfaces

Answer 4

1. condyle of the mandible and mandibular fossa

2. articular tubercle of the temporal bone

Question 5

the synovial membrane

Answer 5

lines the inside of the capsule and the intracapsular posterior aspect of the neck of the mandible

Question 6

gliding movements of protrusion and retrusion

Answer 6

occur between the temporal bone and the articular disc(superior joint cavity)

Question 7

hinge movements of depression and elevation and the pivoting movements

Answer 7

occur in the inferior joint cavity

Question 8

major ligaments of the TMJ joint

Answer 8

1. lateral- intrinsic ligament
2. stylomandibular- extrinsic
3. spenomandibular- extrinsic

Question 9

stylomandibular ligament

Answer 9

1. thickening of the fibrous capsule of the parotid gland

2. does not contribute to the strength of the joint

Question 10

spenomandibular ligament

Answer 10

it’s an accessory ligament of the joint

Question 11

lateral

Answer 11

prevents posterior dislocation of the joint

Question 12

nerve supply of the TMJ

Answer 12

from the auriculotemporal nerve

and the nerve to the masserter

Question 13

stability of TMJ

Answer 13

1. most stable when the teeth are in occlusion
2. forward movement of the condyle is discouraged by the prominence of the articular eminence and by the contraction of the posterior fibres of temporalis
3. backward movement is prevented by fibres of the lateral ligament and by contraction of the lateral pterygoid muscle
4. in the open position the joint is less stable as the condyle lies forward on the slope of the articular eminence
5. forward dislocation is normally opposed by the articular eminence and by tension of the lateral ligament as well as by contraction of the masseter, medial pterygoid and temporalis muscle

Question 14

when the condyle is dislocated forward, reduction is prevented by

Answer 14

spasms of the masseter, medial pterygoid and temporalis muscles, which hold the dislocated jaw open with the condyle in front of the eminence

Question 15

anterior dislocation readily occurs in the

Answer 15

edentulous

Question 16

in addition to the loss of stability resulting from the lack of proper occlusion in the elderly, increased postural elevation of the edentulous mandibular body lowers the

Answer 16

mandibular head and neck and elongates the lateral ligament