Formation of the Mandible and Temporomandibular joint Flashcards Preview

Oral Histology > Formation of the Mandible and Temporomandibular joint > Flashcards

Flashcards in Formation of the Mandible and Temporomandibular joint Deck (43):
1

Ossification Centers

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

2

Intramembranous ossification centers

Ossification centers in the mesenchyme

3

Endochondral ossification centers

Ossification centers within a cartilage model

4

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

True

5

How many ossification centers are in the mandible?

2 - one for each half

6

How many ossification centers are in the maxilla?

2 for each bone (4 total)

7

Mixed ossification centers

Some bones have both intramembranos and endochondral ossification centers

8

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

Temporal bones

9

Intramembranous bone tissue formation

Highly vascular connective tissue where all bone formation occurs

10

Growth sites

Where bone tissue is added to a bone organ

11

Paired Meckel's Cartilage

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

12

Meckels cartilage serves as a model for what?

2 ear ossicles - malleus and incus

13

What appears at the site of Meckel's cartilage

2 ligaments - anterior mallelar and sphenomandibular ligaments

14

What happens to Meckel's cartilage?

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

15

When does mandible formation start?

6th embryonic week

16

Where are the ossification centers for mandible formation

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)

17

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

Anterior and Posterior

18

Anterior growth of the mandible

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

19

Posterior growth of the mandible

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

20

When does osseous union between the 2 mandibular halves occur?

At the end of the first postnatal year

21

Condylar cartilage

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

22

Fate of the proximal end of Meckel's cartilage

Becomes the malleus and incus ossicles
Becomes the anterior mallelar ligament

23

Fate of the middle area of Meckel's cartilage

Becomes the Sphenomandibular ligament

24

Fate of the distal end of Mecke's cartilage

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

25

Joint definition

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

26

What are the different types of joints

Synarthrosis
Amphiarthrosis
Diarthrosis
Ginglymoarthrodial
Gomphosis

27

Synarthrositic joint

Permits little or no mobility
Fibrous and suture jointss

28

Synarthrositic joint example

Between maxillary bones

29

Amphiarthrosis joint

Permits slight mobility
Cartilagenous joints

30

Amphiarthrotic joint example

Pubic Symphysis

31

Diarthrotic joint

Permits a variety of movements
Synovial joints

32

Diarthrotic joint example

Temporomandibular joint

33

Ginglymoarthrodial joint

Dual compartment

34

Gomphosis joint

A joing that binds a tooth to a bone socket

35

What are features of most freely moveable joints?

One joint cavity
Incomplete articular disc
Cartilage articular surfaces

36

What freely moving joint is different from the rest?

TMJ

37

What are some unique features of the TMJ?

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

38

Hyaline Cartilage of the condyle

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

39

When is the condylar cartilage replaced by compact bone?

Age 25

40

When does 2 ossification centers of the mandible form?

6th week IU

41

When does the blastema appear?

8th week IU

42

When does cavitation within the blastema of the TMJ appear?

3rd month IU

43

TMJ blastema

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