Tmj

Question 1

JOINT CAPSULE

Answer 1

• consists of fibrous tissues that covers or wraps the TMJ • it seals the joint space

Question 2

JOINT CAPSULE

attached to TMJ by 2 anterior and 2 posterior lamella:

Answer 2

• posterior and superior: squamoustympanic fissure
• anterior and superior: articular eminence
• anterior and inferior condyle
• posterior and inferior condyle
• laterally: glenoid fossa

Question 3

JOINT CAPSULE

Answer 3

• all lamellas consists of fibrous tissue except superior lamella (fibrous & elastic)
• the connective tissue between the posterior superior and
• the lateral aspect of the capsule is thickened to form a fan-shaped
temporomandibular ligament-restricts the displacement of the mandible

Question 4

SYNOVIAL MEMBRANE

Answer 4

▪ the capsule is lined on its inner surface by synovial membrane
▪ secretes the synovial fluid that occupies the joint cavities
▪ the membrane consists of folds and villi which protrude into the joint
cavity. • the folds increases with age and are more prominent in joints
affected by pathological conditions

Question 5

SYNOVIAL MEMBRANE

▪ Consists of 2 layers:

Answer 5

Cellular intima

Vascular subintima

Question 6

Cellular intima

Answer 6

Consists of synovial cells

embedded in an amorphous, fiber-free intercellular matrix.

Question 7

Vascular subintima

Answer 7

Loose connective tissue

containing vascular elements and scattered with cells such as fibroblasts, macrophages, mast cells, fat cells.

Question 8

cells in vascular subintima consists some elastic fibers which prevent folding of the membrane

Answer 8

Type A(Macrophage like) cells
Type B(Fibroblast like) cells

Question 9

Type A(Macrophage like) cells

Answer 9

• exhibit phagocytic properties.
• cytoplasm of cells contains mitochondria,
lysosomal elements and Golgi complex.

Question 10

Type B(Fibroblast like) cells

Answer 10

• synthesize hyaluronate found in the
synovialfluid.
• cells contain many rough endoplasmic
reticulum

Question 11

FUNCTIONS OF SYNOVIAL FLUID

Answer 11

• provides a liquid environment for the joint
surfaces
• lubrication to increase efficiency of joint
movement and reduce erosion/.
• nutrition to articular surfaces and disk.

Question 12

Histology of the articulating surface

The articulating surface of both the temporal bone and condyle consistsof:

Answer 12

Fibrous layer

Proliferative zone

Question 13

Proliferative zone

Answer 13

contains chrondoblasts associated with the
formation ofcartilage

Chondroblasts forms the extracellular matrix of proteoglycans
and type II collagen and these cells may become entrapped in the
matrix as chondrocytes. With age, the proliferative activity of the
cells ceases. The cartilage is converted to fibrocartilage and
eventually the cartilage is mineralized.
• The proliferative layer can resume their proliferative activity
when the occasion demands.

Question 14

Fibrous layer

Answer 14

dense, largely avascular layer of type I collagen (thicker at
the articular eminence)

Question 15

In child’s condyle:

Answer 15

• the proliferative zone is large
• presence of hypertrophic chondrocytes
(cartilage forming cells) - the zone where
endochondral ossification occurs).

Question 16

Blood supply

Answer 16

Branches of external carotid artery (superficial temporal, deep auricular, anterior tympanic and ascending pharyngeal arteries).

Question 17

BIOMECHANICS OF TMJ

The muscles act on the TMJ to provide stability and to allow the following movements:

Answer 17

Rotatory, Translatory movement

Question 18

Translatory movement

Answer 18

• opening of the mandible more than 2.5 cm • involves translation of the condyle to the
articular eminence

Question 19

Rotatory

Answer 19

• opening of the mandible less than 2.5 cm
• involves rotation of the condyle in the glenoid
fossa (pure hinge movement)

Question 20

ENVELOPE OF MOTION:

Answer 20

Contact points between the
incisors during opening and closing of jaws
Refers to the space within
which all movements of the
mandible occurs 
Limited by TMJ ligaments

Question 21

Envelope of motion:

Consists of two phase:

Answer 21

Opening of less than 2.5 cm involves rotation of the condyle in the glenoid fossa (pure hinge movement)
Opening of more than 2.5 cm involves translation of the condyle to the articular eminence

Question 22

SUBLUXATION

Answer 22

An incomplete dislocation of the condyle with
maximum opening
the condyle translates anterior to the articular
eminence and is able to return to the fossa
after either self manipulation or spontaneous
voluntary retention.
It usually report a momentarily / short duration
of open dislocation with the jaw ‘sticking’ /
temporarily inability to close the jaw
completely.