TMJ

Question 1

What are the fibrous joints?

Answer 1

• Very little movement*
• Sutures - Skull
• Tooth socket - Gomphosis
• Syndesmosis - Immovable CT holding bones together (tibia and fibula)

Question 2

What are cartilaginous joints?

Answer 2

• Little movement*
• Primary (Synchondroses) - Bone and cartilage in direct apposition (Sternocostal junction)
• Secondary (Symphyses) - Fibrous tissue internally in the joint

Question 3

What are synovial jts?

Answer 3

Capsule filled with synovial fluid contained w/in a synovial membrane

Question 4

T/F - The TMJ is a synovial jt.

Answer 4

TRUE

Question 5

What is the TMJ specifically?

Answer 5

Synovial sliding-ginglymoid joint

Question 6

General structure of the TMJ?

Answer 6

-Condyle
—Able to rotate and translate in various ways

• Glenoid fossa
• Articular eminence

Question 7

The TMJ synovial capsule is bound to what 2 things?

Answer 7

Condyle

Glenoid fossa

*Articular disc separates the 2

Question 8

What is the extension of the articular capsule?

Answer 8

ARTICULAR DISC

Question 9

Origins of the mandible?

Answer 9

Intramembranous ossification, except for ramus, and associated with Meckel’s cartilage

Question 10

What forms the primary joint?

Answer 10

Meckel’s cartilage forms the malleus and articulates with the incus

This is how a fetus opens it’s mouth

*This is prior to the development of the condyle and temporal bone

Question 11

What is the secondary joint?

Answer 11

Articulation b/t condylar head and glenoid fossa

Question 12

T/F - The TMJ articular surfaces are covered with fibrous CT, NOT hyaline.
-It’s a dense fibrous coating.

-Why is this an issue?

Answer 12

TRUE

Slow healing

Question 13

What is the dense fibrous tissue on the condyle?

Answer 13

Lamina splendens

Question 14

Tell me about the lamina splendens.

Answer 14

Avascular type I collagen w/ fibroblasts

Question 15

Look at picture on slide 10.

Answer 15

Do it

Question 16

What are the 4 mm of mastication?

Answer 16

Masseter

Med pterygoid

Lat pterygoid

Temporalis

Question 17

T/F - The jt capsule is a dense collagneous sac.

Answer 17

TRUE

Question 18

What do the ligaments associated with the TMJ do?

Answer 18

Stabilizes the jt

Restrict mal-movements

Question 19

What are the 3 ligaments to know about the TMJ?

Answer 19

TMJ ligament - Thickened regions that branch out

Sphenomandibular - Connects sphenoid to mandible

Stylomandibular - Connects styloid process to mandible

Question 20

T/F - Articular disk is continuous with the jt capsule.

Answer 20

TRUE

Question 21

What is the articular disc?

Answer 21

Dense fibrous structure

-Collagen fiber network overlaying fibroblast cells

Question 22

T/F - Posteriorly and anteriorly, the disc is thicker, and the condyle rests on the thinner middle section when jaw is closed

Answer 22

TRUE

Question 23

What are the 2 layers of the synovial membrane?

Answer 23

• Subintima

- Intima

Question 24

What is the subintima?

Answer 24

Loose CT

-Elastin and vasculature

Question 25

What is the intima?

Answer 25

Innermost layer with cells

Question 26

What are the cells of the intima?

Answer 26

-A cells
—Resemble MACROPHAGES

-B cells
—Resemble FIBROBLASTS and contribute PROTEINS in synovial fluid

Question 27

What is the synovial fluid?

Answer 27

Basically blood plasma, containing extra proteins and proteoglycans

Question 28

Tell me about the layers of cartilage.

Answer 28

Progenitor cells->chondroblasts (in a proliferative layer) these secrete ECM w/ type II collagen around themselves

->Once entombed, they form hypertrophic chondrocytes
—THESE UNDERGO ENDOCHONDRAL OSSIFICATION

Question 29

T/F - Mandible is formed by intramembranous ossification, but it is fair to say the articular part of the TMJ is formed by endochondral ossification also.

Answer 29

TRUE

Question 30

T/F - B/c of the endochondral ossification at the articular part, then there is potential for remodeling of the joint in the cases of wear and/or pathologies.

Answer 30

TRUE