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Flashcards in Bone Development Deck (20):
1

Intramembranous Ossification

- Direct
- Mesenchymal Condensation and direct mineralization by osteoblasts
- differentiation of mesenchymal cells into osteoblasts then osteocytes

2

Endochondral Ossifiation

- Indirect
- Ossification of a preexisting cartilage model
- replacement of cartilage with osteoblasts and osteocytes

3

Intramembranous Ossification occurs in.....

- areas of vascularized mesenchyme
- flat bones
- growing short bones
- periosteal bone collar of long bones

4

Intramembranous ossification sequence of events:

1) mesenchymal condensations
2) appearance of blood vessels
3) differentiation into osteoblasts: primary ossification center
4) mineralizaiton by osteocytes
5) spicules/ trabeculae formed
6) interweaving of trabeculae: spongy bone and marrow cavities

5

Endochondral Ossification in Prenatal growth

- Formation of subperiosteal bone collar by intramembranous ossification around hyaline cartilage (width)
- Endochondral ossification- replaces the cartilage with bone (length)

6

Endochondral Ossification in postnatal growth

- Formation of a secondary epiphyseal ossification center in one of the epiphysis following the same mechanism as for primary center
- Epiphyseal growth plate- bone growth in length until adulthood, regulated by GH
- Spongy bone replaces woven bone at the first epiphysis. Articular cartilage remains around the epiphyisis

7

Growth Plate Closure

- The first epiphysis matures: growth plate closes and progressively disappears (16-20y.)
- Only remaining cartilage in the epiphysis is articular cartilage
- growth of second epiphyseal plate
- expansion of central marrow cavity
- bone collar becomes compact bone

8

Adult bone

-Plate no longer present
- compact bone at diaphysis
- spongy bone at epipysis
- Marrow space contains yellow marrow
- periosteum surrounds shaft
- articular cartilage without perichondrium

9

Epiphyseal spicules

- get incorporated into diaphysis

10

Mitotic zone (proliferating zone)

- GH is causing proliferation of chondroblasts
- pushes up height of long bone
- the thickness on the trailing end is converted to bone
- ratchets up

11

Bone Repair

- Blood supply is broken
- Oxygen supply decreases
- Mesenchymal cells go toward cartilage because there is no blood supply
- chondrocytes are formed
- forms a temporary bridge between the two broken bones- 4 days
- Blood vessels re penetrate the cartilage
- they you get cartilage replacement- endochondral

12

Joints

- arthroses
- Synarthrose- permit little or no movement

13

syndesmosis

- Fibrous joints
- Joined by dense connective tissue

14

synostose

- immobilized fused bones (skull)

15

Synchondrose

- bones joined by hayline cartilage
(rib/sternum)
- primary carilaginous joint

16

Symphysis

- secondary cartilaginous joint
- bones joined by fibrocartilage (pubic symphysis, intervertebral discs)

17

Diarthrose

- synovial/ articular joint
- movable joints between long bones
- Articular cartilage (no perichondrium
- Synovial Fluid
- Capsule (2 layers)
1) Outer membrane: fibrous
2) inner membrane: synovial membrane
- A cell: Phagocytic, adjacent to synovial fluid
- B cel: secretes synovial fluid

18

Tendon

- muscle to bone

19

Ligament

Bone to bone

20

Rheumatoid Arthritis

Autoimmune disease causing chronic inflammation of the joint and can also cause inflammation of the tissue around the joints