Musculoskeletal 2 Flashcards Preview

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Flashcards in Musculoskeletal 2 Deck (25):
1

Where are blood vessels in bone?

In the periosteum and in the medullary cavity

2

What does bone remodelling comprise of?

Appositional growth and bone resorption

3

What do perforating (sharpey's) fibre do?

Anchors structure to bone

4

What deposits osteoid?

Osteoblasts

5

Can tissue bone grow by interstitial growth?

No, it's too rigid

6

What is interstitial growth?

A process which involves cells dividing, secreting more extra cellular matrix and growing the tissue from within

7

Where does interstitial growth occur?

In softer tissue that can deform

8

Why does interstitial growth also not occur in bone?

Because bone is designed to resist deformity so it can only grow by adding new bone to an existing surface (appositional growth)

9

Where do appositional growth and bone resorption occur?

Through out the skeletal system, often completely independent of each other (aka bone remodelling)

10

How do long bones grow in length?

By endochondral ossification

11

How do osteoblasts deposit new bone onto a surface (appositional growth)?

In layers or sheets called lamellae

12

What is the collagen fibre arrangement like in lamellar (mature) bone?

Typically put down in the same direction within a layer, but can alternate up to 90 degrees out of phase between the layers

13

What does the arrangement of collagen fibres allow for?

Bond to withstand forces from different directions, making it significantly stronger

14

What are the two forms of lamellar bone?

Spongy and compact

15

Where does lamellae occur?

In osteons

16

What is the normal thickness of compact bone?

Less than 0.4mm

17

Thickness of trabeculae?

18

Where are primary osteons formed?

Around a existing blood vessel on the surface of bone (normally in the periosteum)

19

When does primary osteon formation occur?

When the bone is growing and new bone tissue is being deposited into an existing surface

20

What is another name for compact bone?

Cortical bone

21

What is another name for spongy bone?

Cancellous or trabecular bone

22

First step of osteon formation in compact bone?

Osteoblasts in the active periosteum either side of the blood vessel put down new bone forming ridges

23

Second step of osteon formation in compact bone?

As the bone continues to grow, ridges come together and fuse, forming a tunnel around the blood vessel. The tunnel is now lined with endosteum

24

Third step of osteon formation in compact bone?

Osteoblasts in the endosteum build concentric lamellae onto the walls of the tunnel. The tunnel is slowly filled inward toward the centre forming a new osteon

25

Fourth step of osteon formation in primary bone?

The bone continues to grow outwards as the osteoblasts in the periosteum build new circumferential lamellae. Osteon formation repeats as new periosteal ridges fold over another blood vessel