Formation of the Mandible and Temporomandibular joint

Question 1

Ossification Centers

Answer 1

Initial appearance of bone tissue in the area where each of the 206 bone organs of the body form

Question 2

Intramembranous ossification centers

Answer 2

Ossification centers in the mesenchyme

Question 3

Endochondral ossification centers

Answer 3

Ossification centers within a cartilage model

Question 4

T/F - the number of ossification centers vary from bone to bone

Answer 4

True

Question 5

How many ossification centers are in the mandible?

Answer 5

2 - one for each half

Question 6

How many ossification centers are in the maxilla?

Answer 6

2 for each bone (4 total)

Question 7

Mixed ossification centers

Answer 7

Some bones have both intramembranos and endochondral ossification centers

Question 8

What is an example of a bone that has a mixed ossification center?

Answer 8

Temporal bones

Question 9

Intramembranous bone tissue formation

Answer 9

Highly vascular connective tissue where all bone formation occurs

Question 10

Growth sites

Answer 10

Where bone tissue is added to a bone organ

Question 11

Paired Meckel’s Cartilage

Answer 11

Temporary skeleton of mandibular processes of branchial arch I
Serve as a temporary attachment for muscles that eventually attach to mandible
Serves as temporary anterior lingual plate of forming mandible halves
Serves as an enclosed growth site at the chin end of the mandible halves

Question 12

Meckels cartilage serves as a model for what?

Answer 12

2 ear ossicles - malleus and incus

Question 13

What appears at the site of Meckel’s cartilage

Answer 13

2 ligaments - anterior mallelar and sphenomandibular ligaments

Question 14

What happens to Meckel’s cartilage?

Answer 14

It undergrows growth, mineralization, and resorption while serving as an anterior growth site and is replaxed as temporary anterior lingual plates by encroaching bone tissue of the growing mandible halves

Question 15

When does mandible formation start?

Answer 15

6th embryonic week

Question 16

Where are the ossification centers for mandible formation

Answer 16

Within the mesenchymal tissue lateral to Meckel’s cartilage at the site of the future mental foramina (where the mental and incisive nerves branch from the inferior alveolar)

Question 17

In what direction does the mandible grow from the ossification centers?

Answer 17

Anterior and Posterior

Question 18

Anterior growth of the mandible

Answer 18

The bone incorporates the distal parts of Meckels’ cartilage

This iscorporated part of the cartilage becomes the temporary lingual plate and growth site of each mandible half

Question 19

Posterior growth of the mandible

Answer 19

The bone is in the form of a ‘U’ (or trough) featuring facial and lingual plates
The posterior end of the facial plate incorporates an independent piece of hyaline cartilage that becomes ‘condylar cartilage’ - another growth site of each mandible half

Question 20

When does osseous union between the 2 mandibular halves occur?

Answer 20

At the end of the first postnatal year

Question 21

Condylar cartilage

Answer 21

An independent, cone-shaped area of cartilage that becomes enclosed in the posterior end of the facial bone

Question 22

Fate of the proximal end of Meckel’s cartilage

Answer 22

Becomes the malleus and incus ossicles

Becomes the anterior mallelar ligament

Question 23

Fate of the middle area of Meckel’s cartilage

Answer 23

Becomes the Sphenomandibular ligament

Question 24

Fate of the distal end of Mecke’s cartilage

Answer 24

Temporary anterior lingual plate
Growth sites of the mandible halves - the cartilage mineralizes, resorbes, and is replaces by bone tissue of the anterior lingual plate of the mandible

Question 25

Joint definition

Answer 25

A place of union or junction between two or more bones of the skeleton

Question 26

What are the different types of joints

Answer 26

``` Synarthrosis Amphiarthrosis Diarthrosis Ginglymoarthrodial Gomphosis ```

Question 27

Synarthrositic joint

Answer 27

Permits little or no mobility | Fibrous and suture jointss

Question 28

Synarthrositic joint example

Answer 28

Between maxillary bones

Question 29

Amphiarthrosis joint

Answer 29

Permits slight mobility | Cartilagenous joints

Question 30

Amphiarthrotic joint example

Answer 30

Pubic Symphysis

Question 31

Diarthrotic joint

Answer 31

Permits a variety of movements | Synovial joints

Question 32

Diarthrotic joint example

Answer 32

Temporomandibular joint

Question 33

Ginglymoarthrodial joint

Answer 33

Dual compartment

Question 34

Gomphosis joint

Answer 34

A joing that binds a tooth to a bone socket

Question 35

What are features of most freely moveable joints?

Answer 35

One joint cavity Incomplete articular disc Cartilage articular surfaces

Question 36

What freely moving joint is different from the rest?

Answer 36

TMJ

Question 37

What are some unique features of the TMJ?

Answer 37

Formed by the joining of the temporal and mandibular bones Complete articular disc Two joint concavities Soft connective tissue articulating surface

Question 38

Hyaline Cartilage of the condyle

Answer 38

Growth site for the mandible Appositional growth occurs between the articular connective tissue surface and the condylar cartilage At the lower end, the cartilage is mineralized, resorbed, and replaced by bone

Question 39

When is the condylar cartilage replaced by compact bone?

Answer 39

Age 25

Question 40

When does 2 ossification centers of the mandible form?

Answer 40

6th week IU

Question 41

When does the blastema appear?

Answer 41

8th week IU

Question 42

When does cavitation within the blastema of the TMJ appear?

Answer 42

3rd month IU

Question 43

TMJ blastema

Answer 43

Where the condylar cartilage, articular disc, two joint concavities, and soft tissue articular surfaces all form