L11: Osteogenesis & Joints

Question 1

layers of membrane bone

Answer 1

2 layers of compact bone with spongy bone layer enclosed = dipole

Question 2

3 main factors of intramembranous bone formation

Answer 2

1. well-vascularized
2. no preceded by cartilage
3. aggregate of mesenchymal cells differentiate directly into osteoid producing osteoblasts

Question 3

initial bone laid down by intramembranous bone formation

Answer 3

initial bone is woven

collagen fibers are random = haphazard/unorganized bone

Question 4

role of mesenchymal cells in intramembranous bone formation

Answer 4

signals tell cells to aggregate
become osteoblasts
which secrete osteoid

Question 5

blastema

Answer 5

osteoblasts secrete osteoid trapping themselves

center of the blastema is the ossification center for IMB formation

Question 6

osteocytes in IMB formation

Answer 6

central blastema osteoblasts become osteocytes

form a syncytium

Question 7

when does endochondral bone stop?

Answer 7

when bone replacement overtakes cartilage formation

Question 8

growth in bone diameter

Answer 8

diaphysis - primary ossification center

Question 9

growth in bone length

Answer 9

epiphysis - secondary ossification center

Question 10

growth in bone diameter and length follow what type of growth pattern?

Answer 10

endochondral

cartilage replacement

Question 11

zones of the epiphyseal plate

Answer 11

reserve zone
proliferation zone
hypertrophic zone
vascular invasion zone

Question 12

responsible for growth in length as erosion and deposition advance towards this region

Answer 12

reserve zone

full of primitive hyaline cartilage

Question 13

proliferation zone

Answer 13

chondrocytes align vertical and in parallel columns

Question 14

apoptosis of chondrocytes

Answer 14

hypertrophic zone

territorial matrix is calcified

Question 15

blood vessels penetrate transversely

Answer 15

vascular invasion zone

blood vessels carry in osteoprogenitor cells

Question 16

explain the osteoclastic chase

Answer 16

mvt of the osteoblasts

chasing the reserve zone

Question 17

explain the chondrocytic run mechanism

Answer 17

direction of cartilage growth
away from the vascular invasion zone
bone grows in length until osteoblasts win the chase

Question 18

steps in bone remodeling

Answer 18

1. activation
2. resorption
3. reversal
4. formation

Question 19

activation

Answer 19

osteoclast precursors recruited to haversian canal
differentiate
osteoclasts line bone lamella
resorption begins

Question 20

resorption

Answer 20

osteoclasts absorb bone slightly beyond the boundary of the original osteon

Question 21

reversal

Answer 21

osteoclasts end and osteoblasts begin
lay down new osteoid
a cement line indicates boundary of newly organized lamella

Question 22

formation

Answer 22

osteoblasts finish laying down bone
become trapped in their secretions
new osteon formed

Question 23

a structure where two bones comes together

Answer 23

joint

Question 24

major types of joints

Answer 24

amphiarthrosis - cartilage
synarthrosis - fibers
diarthrosis - moveable

Question 25

types of cartilage joints

Answer 25

symphysis -fibrocartilage

Synchondrosis – hyaline

Question 26

examples of fibrocartilage joints

Answer 26

symphysis

pubic symphysis
intervertebral discs

Question 27

examples of hyaline cartilage joints

Answer 27

Synchondrosis

epiphyseal plate
1st sternocostal joint

Question 28

types of fibrous joints

Answer 28

suture - calvaria
Gomphosis - teeth in alveoli
Synchondrosis - interosseous membrane

collagen or elastic

Question 29

types of synovial joints

Answer 29

monoaxial/plane
biaxial
triaxial

Question 30

hinge and pivot joints

Answer 30

monoaxial

Question 31

condyloid and sellaris joints

Answer 31

biaxial

Question 32

ball and socket joint

Answer 32

triaxial

Question 33

MCPs and atlantoaxial joints

Answer 33

condyloid

Question 34

saddle joint

Answer 34

sellaris

thumb

Question 35

list the 5 components of the histology of synovial joints

Answer 35

1. articular cartilage
2. joint capsule
3. synovial membrane
4. synovial fluid
5. synovial cells

Question 36

articular cartilage

Answer 36

• made of hyaline cartilage
• lacks perichondrium
• not lined by synovial membrane

Question 37

synovial joint capsule

Answer 37

• dense CT, vascularized
• lined by synovial membrane
• attaches to edges of articular cartilage

Question 38

synovial membrane

Answer 38

• highly vascularized
• 1-3 layers of synovial cells
• no basal lamina

Question 39

what does fenestrated capillaries mean?

Answer 39

fenestrated = windows
capillaries w/ holes
leaky

Question 40

synovial fluid

Answer 40

• contain mucin

- produced by synovial cells

Question 41

mucin

Answer 41

hyaluronic acid protein complex

Question 42

synovial cells

Answer 42

type A - macrophage like

type B - fibroblast like