mandible and TMJ 3

Question 1

while bone formation starts in temporal blastema, the condylar blastema is still

Answer 1

consists of undifferentiated bipotential periosteal cells with bipotential .

Question 2

what are the differences betwenn condylar and epipphyseal cartilagesin long bone?

Answer 2

epiphyseal has

1) ordered columns of cartilaginous cells
2) well-defined, elongated columns of chondroblast

Question 3

Unlike most synovial joints, the articular surfaces of which are covered with hyaline cartilage, the temporomandibular articulation is covered by a layer of

Answer 3

fibrous tissue

Question 4

mandibular condyle has _____ growth capacity? its cartilage can proliferate in any combination of ____ and ____ directions

Answer 4

multidirectional

*superior and posterior directions (as needed to provide the best anatomic placement)

Question 5

chondroblasts get entrapped as chondrocytes in a matrix made of?

Answer 5

proteoglycans and type II collagen

Question 6

hypertrophy

Answer 6

increase in the size

*in this case, chondrocytes grow as they mature and get stuck in matrix

Question 7

Following the production of this cartilage, endochondral ossification occurs and involves ?

Answer 7

mineralization of the cartilage, vascular invasion, loss of chondrocytes, and differentiation of osteoblasts to produce bone on the mineralized cartilaginous framework

Question 8

progenitor cells in the perichondrium and periosteum overlying the condyle can differentiate into?

Answer 8

chondrocytes or osteoblasts

Question 9

what are the five bone formation-related cell populations are present in the condyle?

Answer 9

progenitor cells
chondrocytes
hypertrophied chondrocytes
osteoblasts
osteocytes

Question 10

Peripheral condylar cartilage has ____ cells that differ morphologically from
chondrocytes, osteocytes, and progenitor cells. they are surrounded by?
***what type of bone?

Answer 10

peculiar cells
chondrocyte-like appearance, but are
surrounded by eosinophilic matrix like osteocytes
**CHONDROID BONE

Question 11

what is Chondroid bone ?

Where is it found?

Answer 11

specialized calcified tissue with morphological properties intermediate between those of bone and cartilage
**found in craniofacial regions, including the mandibular symphysis, alveolar bone, glenoid fossa, and mandibular condylar cartilage

Question 12

what are the 3 phases of TMJ development?

Answer 12

(1) blastematic stage (weeks 7–8 of development)
(2) cavitation stage (weeks 9–11)
(3) maturation stage (after week 12)

Question 13

What appears along with the chondrification of the mandibular condyle in week 9?

Answer 13

inferior articular cavity appears

Question 14

Primary cartilage structures vs secondary cartilage structures?

Answer 14

• primary= epiphysis, synchondrosis, nasal septum, ethmoid, sphenoid
• secondary= condyle, coronoid, mid palatal suture, fracture callus

Question 15

The ______ of the mandibular condylar cartilage is continuous with the ______ of mandibular ramus

Answer 15

The perichondrium of the mandibular condylar cartilage is continuous with the periosteum of the mandibular ramus

Question 16

the fibrous layer of the periosteum continues as the _____ of the Mandibular Condylar Cartilage

Answer 16

articular layer

Question 17

the osteogenic layer of the periosteum continues as the __________ of the Mandibular Condylar Cartilage

Answer 17

prechondroblastic layer

Question 18

What are the layers of TMJ: superficial to deep?

Answer 18

Articular layer= most superficial
Prechondroblastic layer
Chondroblastic layer
Hypertrophic layer
Cartilage-bone interface

Question 19

Articular layer of TMJ

Answer 19

• Continuous with fibrous layer of the periosteum
• Fibroblasts in a type I collagen matrix
• Some elastic fibers
• Very low cell turnover

Question 20

Prechondroblastic layer of TMJ

Answer 20

• Continuous with osteogenic layer of periosteum
• Multipotential mesenchymal cells
• Sparse matrix contains type I collagen and proteoglycans (no type II collagen)
• Majority of cell divisions occur in this layer, especially in the rounded cells

Question 21

Chondroblastic layer of TMJ

Answer 21

• Begins with lowest zone of flattened cells
• Considerably more matrix than
in prechondroblastic layer
• Matrix is rich in type II collagen and aggrecan
• Cells are not oriented in palisades/rows (like growth plate or cranial base) but have NO direct orientation

Question 22

Hypertrophic layer of TMJ

Answer 22

Cells enlarge greatly, fill lacunae
• ***Matrix contains both type I and type II collagen, as well as type X collagen, a synthetic product specific to hypertrophic chondrocytes
• Deeper layers are mineralized

Question 23

Cartilage-bone interface layer of TMJ

Answer 23

• Hypertrophic chondrocytes undergo apoptosis or metaplastic change into
osteoblasts
• Blood vessels invade, bringing with them cells that destroy cartilage matrix
• New bone is deposited in and around septa of cartilage matrix

Question 24

what is synovial fluid?

Answer 24

• -produced by synovial membrane intimal cells
• -forms viscous fluid (plasma, protein, and mucin)
• -contains many varying types of cells

Question 25

what does synovial fluid do?

Answer 25

• provides lubrication
• nutrition
• removes foriegn stuff

Question 26

fibrochondrocytes synthesis? found?

Answer 26

found in articular discs; found in FIBROCARTILAGES

* synthesize BOTH type 1 and type 2 collagens AND proteoglycans

Question 27

wwhat is Articular Disc

Answer 27

Fibroblasts and elastic fibers in a collagenous matrix

***avascular and aneural in loaded regions

Question 28

In adults, both TMJ disc and knee meniscus are?

Answer 28

FIBROCARTILAGES

*in young ppl it is dense and irregular with condrocytes