Formation Mandible&TMJ

Question 1

Define: Ossification Center

Answer 1

Initial appearance of bone tissue in area where all bone organs of body form

Question 2

How many ossification centers form in mandible? Maxillae? Intramembranous or Endochondral?

Answer 2

2 in mandible (Intramembranous-1 for each half which JOIN AT END OF 1st POSTNAL YEAR), 4 in maxillae (Intramembranous-2 centers in each half)

Question 3

Within what environment does intramembranous bone development occur?

Answer 3

Mesenchyme

Question 4

What type of bone development occurs within a cartilage model?

Answer 4

Endochondral development

Question 5

What serves as a temporary skeleton of mandibular processes of B.A. 1?

Answer 5

The paired Meckel’s cartilages

Question 6

What is the role of Meckel’s cartilages in reference to muscles that eventually attach to the mandible?

Answer 6

Meckel’s cartilages serve as a temporary attachment for the muscles until the mandible forms

Question 7

Which 2 ear ossicles are modeled from Meckel’s cartilage?

Answer 7

Malleus & Incus. Stapes forms from arch II.

Question 8

What two ligaments form from retrogressive changes of Meckel’s cartilage?

Answer 8

Anterior Mallelar and Sphenomandibular ligaments

Question 9

Meckel’s cartilage serves as an enclosed growth site for which end of the mandible halves?

Answer 9

The chin end (distal)

Question 10

What type of cartilage is Meckel’s cartilage characterized as?

Answer 10

Hyaline

Question 11

T/F: Mandible begins development in the 4th embryonic week.

Answer 11

False-begins at 6th week (1st to show ossification center in entire human body)

Question 12

Are mandibular ossification centers located medially, laterally, lingual, or buccal to Meckel’s cartilage?

Answer 12

The ossification centers are located laterally to Meckel’s cartilage.

Question 13

What is significant of the future site of the mental foramina?

Answer 13

This site is where the mandibular ossification centers begin.

Question 14

Which directions do the mandibular ossification centers grow?

Answer 14

Anterior and posterior.

Question 15

Which portion of mandibular ossification center becomes the temporary lingual plate?

Answer 15

The anterior portion

Question 16

The condylar cartilage is incorporated by which portion of the 2 mandibular ossification centers?

Answer 16

posterior portion

Question 17

What type of cartilage is the condylar cartilage made up of?

Answer 17

Hyaline

Question 18

T/F: Condylar cartilage arises from Meckel’s cartilage

Answer 18

False-It is totally independent of Meckel’s

Question 19

T/F: Condylar cartilage grows around the posterior portion of the facial bone plate.

Answer 19

False-the condylar cartilage becomes an enclosed growth site of the facial bone plate

Question 20

Does the middle area of Meckel’s cartilage give rise to the anterior mallelar or sphenomandibular ligament?

Answer 20

Middle area=sphenomandibular ligament

Proximal end=anterior mallelar ligament (closest to ossicles)

Question 21

What joint permits little/no mobility? Ex:b/t max bones, b/t temporal and parietal bones.

Answer 21

Synarthrosis Joint

Question 22

What joint permits slight mobility? Ex:pubic symphysis

Answer 22

Amphiarthrosis Joint

Question 23

What joint permits free variety of movements? Ex:TMJ

Answer 23

Diarthrosis Joint

Question 24

What can ginglymoarthrodial joint do?

Answer 24

MediLexicon website definition: can hinge and glide.

Wikipedia says an example is TMJ joint b/c it can hinge and glide. All I noted was that it was a Gliding Joint

Question 25

Name the 4 unique features of the TMJ:

Answer 25

Complete articular disc, Two joint cavities, Soft connective tissue (differentiates from all other joints), articulating surfaces.

Question 26

When does cavitation of TMJ articular disc occur?

Answer 26

3rd month IU

Question 27

At what age is condylar cartilage replaced with compact bone tissue?

Answer 27

Around age 25

Question 28

T/F: As TMJ ages, articular surface of condyle becomes more cellular

Answer 28

False: After about 25 years, articular surface of condyle becomes more fibrous.

Question 29

When does the appearance of blastema (rudiments) of TMJ occur?

Answer 29

8th week IU

Question 30

What forms from the TMJ blastema?

Answer 30

Condylar cartilage, Articular disc, Both joint cavities, Soft tissue articular surfaces.