Temporomandibular Joint (TMJ)

Question 1

Ruffini Corpuscles

Answer 1

Proprioception

Question 2

Pacinian Corpuscles

Answer 2

Dynamic Mechanoreception

Question 3

Golgi Tendon Organs

Answer 3

Static Mechanoreception

Question 4

Free Nerve Endings

Answer 4

Pain

Question 5

The TMJ is classified as a synovial sliding-ginglymoid

hinged) joint: (5

Answer 5

 Synovial joints permit movement between two bones.

 Each bone is covered by hyaline cartilage.
 The two bones are united and surrounded by a fibrous
capsule thereby creating a joint cavity.
 The joint cavity is filled with synovial fluid (approximately
1mL) that is derived from villus cells which line the internal
surface of the capsule.
 Also present is a fibrous disc which separates the bones

Question 6

Both the condylar neck and head develop by

Answer 6

endochondral ossification.

Question 7

The condylar head develops by —, and has multidirectional growth capacity. Unlike long bones of the body, which
also develop by —, the cartilage cells in the condylar head and neck do not exhibit

Answer 7

endochondral ossification
endochondral ossification

ordered columns (a characteristic of the epiphyseal growth plates in long bones)

Question 8

Bones of the TMJ are the (2)

Answer 8

glenoid fossa and the mandibular condyle.

Question 9

Fibrous capsule
Superior and inferior heads of the lateral pterygoid muscle
• Superior head attaches to the
• Inferior head attaches to the

Answer 9

joint capsule and articular disc (a.k.a. meniscus)

condylar neck in the pterygoid fovea

Question 10

The articulating surfaces are covered with a layer of fibrous tissue. With increasing age, the deeper portions of the fibrous covering may exhibit

Answer 10

islands of cartilage.

Question 11

Retrodiscal Connective Tissue (a.k.a. bilaminar zone):

Answer 11

Comprised
of collagen and elastic fibrous connective tissue, fat cells, and is
highly vascular. Elastic fibers from this bilaminar zone insert into
the petrotympanic fissure.

Question 12

The disc is attached to the medial
and lateral surfaces of the
condyle, but not the temporal
bone. Thus,

Answer 12

when the mandible
moves, the disc moves as well,
traveling over the anterior
surface of the articular fossa.

Question 13

All articulation is on the — portion of the disc.

Answer 13

fibrous

Question 14

All articulation is on the fibrous portion of the disc. This dense area also restricts the (2)

Answer 14

posterior movement of the mandible, and maintains

the condyle in the anterior part of the glenoid fossa.

Question 15

The vascular retrodiscal area allows the mandible to move freely in an

Answer 15

anterior

direction.

Question 16

The — membrane lines the inner surface of

the fibrous capsule

Answer 16

synovial

Question 17

The TMJ synovial membrane consists of three

distinct layers of tissue: (3)

Answer 17

• The most peripheral (external) layer is the fibrous capsule of the joint
• The intermediate layer is the vascular subintima
• The most internal layer is termed the intimal layer

Question 18

The intimal layer contains two cell types:

Answer 18

Type A Synovial Cells:

Type B Synovial Cells:

Question 19

Type A Synovial Cells:

Answer 19

 Macrophage-like cells that exhibit phagocytic functions
and are capable of producing inflammatory cytokines,
e.g., IL-1, IL-6, IL-8, and TNF-α

Question 20

Type B synovial Cells:

Answer 20

 Fibroblast-like cells that synthesize hyaluronate which
is a major component of the synovial fluid in both the
superior and inferior compartments of the joint.

Question 21

Inflammatory joint disease

Answer 21

Chronic or acute joint trauma may cause the Type A synovial cells
to undergo a syncytial (fusing) transformation into multinucleated
giant cells that exhibit osteoclastic-like functions (i.e. resorption
of bone and cartilage). Thus, the articular surfaces, including the
joint meniscus, are subjected to cellular mediated surface
resorption as long as levels of IL-1, IL-6, IL-8, and TNF- are
elevated.

Question 22

If the inflammatory response is of sufficient intensity and

duration,

Answer 22

bone and cartilage resorption can also take place within
the spongiosa of the condylar head and subjacent condylar neck.
Thus, resorption can actually occur simultaneously on both the
external and internal surfaces of the condyle.

Question 23

With these chronic inflammatory changes, — are noted on the condylar heads. Also, a decreased vascularity is found in the
retrodiscal area, leading to

Answer 23

osteophytes

pain on function.

Question 24

Internal Derangement:

Answer 24

the disc is trapped in the antero-medial position,

causing limited opening, pain, and “clicking” upon opening