Musculoskeletal 2

Question 1

Where are blood vessels in bone?

Answer 1

In the periosteum and in the medullary cavity

Question 2

What does bone remodelling comprise of?

Answer 2

Appositional growth and bone resorption

Question 3

What do perforating (sharpey’s) fibre do?

Answer 3

Anchors structure to bone

Question 4

What deposits osteoid?

Answer 4

Osteoblasts

Question 5

Can tissue bone grow by interstitial growth?

Answer 5

No, it’s too rigid

Question 6

What is interstitial growth?

Answer 6

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

Question 7

Where does interstitial growth occur?

Answer 7

In softer tissue that can deform

Question 8

Why does interstitial growth also not occur in bone?

Answer 8

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

Question 9

Where do appositional growth and bone resorption occur?

Answer 9

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

Question 10

How do long bones grow in length?

Answer 10

By endochondral ossification

Question 11

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

Answer 11

In layers or sheets called lamellae

Question 12

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

Answer 12

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

Question 13

What does the arrangement of collagen fibres allow for?

Answer 13

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

Question 14

What are the two forms of lamellar bone?

Answer 14

Spongy and compact

Question 15

Where does lamellae occur?

Answer 15

In osteons

Question 16

What is the normal thickness of compact bone?

Answer 16

Less than 0.4mm

Question 17

Thickness of trabeculae?

Question 18

Where are primary osteons formed?

Answer 18

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

Question 19

When does primary osteon formation occur?

Answer 19

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

Question 20

What is another name for compact bone?

Answer 20

Cortical bone

Question 21

What is another name for spongy bone?

Answer 21

Cancellous or trabecular bone

Question 22

First step of osteon formation in compact bone?

Answer 22

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

Question 23

Second step of osteon formation in compact bone?

Answer 23

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

Question 24

Third step of osteon formation in compact bone?

Answer 24

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

Question 25

Fourth step of osteon formation in primary bone?

Answer 25

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