Lecture 22 9/27/23

Question 1

What is endochondral ossification?

Answer 1

replacement of hyaline cartilage template by bone

Question 2

What is the responsibility of the physis?

Answer 2

longitudinal growth of bone

Question 3

In what direction does the physis grow bone?

Answer 3

towards the diaphysis

Question 4

What are the layers of the physis?

Answer 4

-resting chondrocytes
-proliferating chondrocytes
-hypertrophied chondrocytes
-calcified cartilage matrix

Question 5

Which region of the physis is the weakest?

Answer 5

hypertrophied chondrocytes

Question 6

Why is the hypertrophied chondrocyte layer of the physis the weakest?

Answer 6

-large cells filled with glycogen
-no matrix

Question 7

What happens to the chondrocytes in the calcified matrix?

Answer 7

they undergo apoptosis

Question 8

How do osteoblasts interact with the calcified matrix?

Answer 8

it turns the calcified matrix into osteoid

Question 9

How does the epiphysis grow bone?

Answer 9

from the articular-epiphyseal cartilage complex (growth plate)

Question 10

How long does the physis persist?

Answer 10

until skeletal maturity

Question 11

Which type of cartilage remains following skeletal maturity?

Answer 11

articular cartilage

Question 12

What is a type one Salter-Harris fracture?

Answer 12

physis fracture at resting chondrocytes layer

Question 13

What is a type two Salter-Harris fracture?

Answer 13

physis fracture at the hypertrophied chondrocytes layer

Question 14

What are the characteristics of type 3 and type 4 Salter-Harris fractures?

Answer 14

-partial fractures at physis
-some of bone continues to grow, other has altered growth

Question 15

How does type # relate to severity of the Salter-Harris fracture?

Answer 15

-higher type # is associated with greater disruption to normal function and growth

Question 16

What is intramembranous ossification?

Answer 16

replacement of mesenchymal template from bone

Question 17

What are the characteristics of intramembranous ossification?

Answer 17

-bone forms from condensed mesenchymal cells
-cartilage not involved
-forms flat bones of skull and clavicle

Question 18

What are the characteristics of bone remodeling?

Answer 18

-occurs constantly, even in adults
-weight bearing determines bone density

Question 19

What are the characteristics of fibrous joints?

Answer 19

-bones connected by dense collagen
-little to no movement
-skull sutures

Question 20

What are the characteristics of cartilaginous joints?

Answer 20

-bones connected by fibrocartilage
-little to no movement
-intervertebral discs

Question 21

What are the characteristics of synovial joints?

Answer 21

-ends of bones covered by hyaline cartilage
-bones connected by ligaments and fibrous joint capsule

Question 22

What is the synovial membrane?

Answer 22

-lining on the inside of the synovial joint capsule
-synoviocytes produce the synovial fluid

Question 23

What are the functions of the synovial fluid?

Answer 23

-lubricate the joint
-provide nutrients to the cartilage