TMJ

Question 1

What type of joints generally permit very little movement?

Answer 1

Fibrous joints

Question 2

Give three examples of Fibrous joints

Answer 2

1. Suture (in the skull)
2. Tooth socket (gomphosis)
3. Syndesmosis (plural syndesmoses)

Question 3

What is a syndesmosis?

Answer 3

Immovable connective tissue holding bones together (tibia and fibula)

Question 4

Other than fibrous joints, what other type of joint permit very little movement?

Answer 4

Cartilaginous joints

Question 5

What are the two types of cartilaginous joints?

Answer 5

1. Primary

2. Secondary

Question 6

What is a primary cartilaginous joint?

Answer 6

• Synchondroses

- Bone and cartilage in direct apposition (sternocostal junction)

Question 7

What is a secondary cartilaginous joint?

Answer 7

• Symphyses

- Fibrous tissue internally in the joint

Question 8

What type of joints are typically thought of as moving parts?

Answer 8

Synovial joints

Question 9

Synovial joints consists of what?

Answer 9

A capsule filled with synovial fluid contained in a synovial membrane

Question 10

What type of joint is the TMJ?

Answer 10

• Synovial

- Specifically a synovial sliding-ginglymoid joint

Question 11

The TMJ articulation is composed of what?

Answer 11

1. Condyle
2. Mandible
3. Glenoid fossa

Question 12

More than opening and closing, the TMJ can perform what other types of movements?

Answer 12

Combinations of:

1. Protrusive
2. Extrusive
3. Retrusive

Question 13

What provides the track that the condyle slides along?

Answer 13

The glenoid fossa

Question 14

What binds the condyle in the fossa anteriorly?

Answer 14

Articular eminence

*Condyle moves in front of it when the jaw opens

Question 15

The ______ is able to rotate and translate in various ways

Answer 15

Condyle

Question 16

The synovial cavity is divided into two compartments by what?

Answer 16

the articular disk

Question 17

What are the two compartments of the TMJ?

Answer 17

1. Upper joint cavity (adjacent to glenoid fossa)

2. Lower joint cavity (adjacent to the condyle)

Question 18

T/F The articular disc is a distinct structure in the TMJ

Answer 18

False, it is effectively an extension of the synovial capsule

Question 19

The articular disk runs between two bones, then flares outwards in sheets, attaching to both the ___ and the ______, and thus envelopes the joint.

Answer 19

1. Condyle

2. Glenoid fossa

Question 20

Mandible forms by _________ ossification and is associated with what type of cartilage?

Answer 20

1. Intramembranous

2. Meckels

Question 21

Meckel’s cartilage forms the _______ directly and articulates with the ________. This forms a primitive _________ joint before the development of the condyle and temporal bone

Answer 21

1. Malleus
2. Incus
3. Primary

Question 22

Articulation between the temporal bone and then forms the TMJ is what type of joint?

Answer 22

Secondary

Question 23

The articular surfaces of the joint are covered with what?

Answer 23

Fibrous connective tissue

*This is different from hyaline cartilage

Question 24

What is the fibrous covering of the condyle known as?

Answer 24

Lamina splendens

Question 25

Describe the lamina splendens

Answer 25

A layer of mostly avascular type I collagen with smattering of fibroblasts scattered around

Question 26

The glenoid fossa is covered by a ________ attached directly to the _____, while the articular eminence is overlaid by ________

Answer 26

1. Thin fibrous layer 2. Temporal bone 3. Thicker fibrous layer

Question 27

T/F There is a significant amount of cartilage associated with the articular surfaces of the joint proper

Answer 27

False, but there is some to be found deeper into the condyle and the articular eminence

Question 28

The layers of cartilage found deep in the condyle and articular eminence have a layer of progenitor cells with spawn ______, which then secrete _____ containing ______ around themselves

Answer 28

1. Chondroblasts 2. ECM 3. Type II collagen

Question 29

Once the chondroblasts do their thing, they form _______ chondrocytes, which in turn undergo ________ ossification and leave a layer of __________

Answer 29

1. Hypertrophic Chondrocytes 2. Endochondral 3. Fibrocartilage

Question 30

The formation of the hypertrophic chondrocytes and the endochondral ossification happens at what stages in life for each relevant part of the joint?

Answer 30

1. Occurs early in life in the articular eminence | 2. Condyle it happens around the age of 30

Question 31

The mandible is formed by intramembranous ossification but it is fair to say that the articular part of the TMJ is formed by _________

Answer 31

Endochondral ossification

Question 32

What does the joint capsule form for the TMJ?

Answer 32

The dense collagenous sac that the joint is located within

Question 33

The capsule has thickened regions which branch out to form _______

Answer 33

the temporomandibular ligament

Question 34

What does the tempormandibular ligament do?

Answer 34

Most important for restricting lateral and medial movement when the joint articulates

Question 35

The temporomandibular ligament restricts movement in 3 planes. What are they?

Answer 35

1. Medial-lateral 2. Superior-inferior 3. Posteriorly

Question 36

Name to other ligaments in the TMJ that limit the inferior movement of the joint when the jaw is open

Answer 36

1. Spenomandibular ligament | 2. Stylomandibular ligament

Question 37

Posteriorly and anteriorly the articular disk is ______, leaving the condyle to rest on the thinner middle section when the jaw is closed

Answer 37

Thicker

Question 38

The articular disk is totally continous with the _________

Answer 38

Joint capsule

Question 39

The articular disk is a dense ______ structure and forms a surface for the head of the condyle to slide along when the jaw opens

Answer 39

fibrous

Question 40

In the articular disk, there is a _______ network that overlays _______ cells

Answer 40

1. Collagen fiber | 2. Fibroblast

Question 41

The joint capsule is lined by the ______, and contains a number of folds, which form _____ projecting into the joint cavity

Answer 41

1. Synovial membrane | 2. Villi

Question 42

What are the two layers of the Synovial membrane?

Answer 42

1. Subintima | 2. Intima

Question 43

Describe the subintima

Answer 43

- Layer of loose CT containing elastin fibers and supporting vasculature - Contains various cells including macrophages, adipocytes, fibroblasts, mast cells and possibly others - It is more or less continuous with the fibrous tissue of the capsule

Question 44

Describe the intima

Answer 44

- Innermost layer of synovial membrane | - Contains several layers of the synovial cells

Question 45

Name the two types of synovial cells that can be found in the intima

Answer 45

1. A cells | 2. B cells

Question 46

Describe the A cells in the synovial membrane

Answer 46

Resemble macrophages

Question 47

Describe the B cells in the synovial membrane

Answer 47

Like fibroblasts but contribute proteins found in the synovial fluid

Question 48

Describe the synovial fluid itself

Answer 48

Basically blood plasma, containing extra proteins and proteoglycans

Question 49

Name the 4 muscles of mastication

Answer 49

1. Masseter 2. Temporalis 3. Medial pterygoid 4. Lateral pterygoid