Bone and cartilage

Question 1

What are the types of bone

Answer 1

Cortical, compact bone​
-dense outer plate​
-80-85% of skeleton​

Cancellous, spongy bone​
-internal trabecular scaffolding​
-15-20% of skeleton

Question 2

What penetrates the alveolar cortical bone lining tooth sockets

Answer 2

Bundles of collagen fibres of PDL

Question 3

What is another name for the penetrated alveolar bone in tooth sockets

Answer 3

bundle bone

Question 4

What is the composition of bone by weight

Answer 4

60% inorganic​
-Hydroxyapatite

15% water

25% organic​
Collagen (90%)​
Glycoproteins​
-Osteocalcin​
-Osteonectin​
-Osteopontin​
-Sialoproteins​
Proteoglycans (GAGs)​
-Chondroitin SO4​
-Heparan SO4

Question 5

What are the types of microscopic bone

Answer 5

Lamellar bone
woven bone

Question 6

What are the properties of woven bone

Answer 6

rapidly laid down​

Irregular deposition of collagen​

present in fetus, ​

fracture repair (callus)​

contains many osteocytes

Question 7

What causes the presence of woven bone

Answer 7

Fractures/breaks

Question 8

What are the properties of lamellar bone

Answer 8

laid down more slowly​

Collagen fibres laid down in parallel​

normal form in adult​

contains fewer osteocytes

Question 9

Do canals contain blood vessels

Answer 9

yes

Question 10

How is compact bone structured

Answer 10

Laid done in concentric lamellae (lamellar bone)
Form longitudinal columns
Organised in Haversian systems around central (Haversian) canal
Lateral (Volkman’s) canals

Question 11

What are Volkman’s canals

Answer 11

Link haversian canals together

Question 12

What are haversian systems called

Answer 12

osteons

Question 13

Within osteons or haversian systems where were osteocytes present

Answer 13

Lacunae

Question 14

How does cancellous bone appear histologically

Answer 14

Lots of space present

Network of thin trabeculae​

Trabeculae consist of lamellae​

Osteocytes present​

No obvious Haversian systems​

The bone is thin, and nutrients can diffuse in​

Bone marrow present in the spaces between trabeculae

Question 15

What are osteoblasts derived from

Answer 15

mesenchymal stem cells

Question 16

What do osteoblasts do

Answer 16

Synthesise and secrete collagen fibres forming a matrix

Question 17

How is the osteoblast matrix mineralised

Answer 17

Calcium salts

Question 18

What forms the osteocytes in bone

Answer 18

They are the osteoblasts that become trapped in mineralised bone and lie within spaces (lacunae)

Question 19

How do osteocytes communicate

Answer 19

Via cytoplasmic processes that run in canaliculi

Question 20

What are osteoclasts derived from

Answer 20

Haemopoietic stem cells

Question 21

How can osteoclasts be identified

Answer 21

Large multi-nucleated cells

Question 22

Where are osteoclasts found

Answer 22

In concavities in the bone (Howships lacunae)

Question 23

What is bone remodelling

Answer 23

The removal and replacement of bone tissue without change in overall shape

Question 24

What percentage of cortical bone is replaced each year

Answer 24

2%

Question 25

What percentage of cancellous bone is replaced each year

Answer 25

25%

Question 26

What things regulate bone remodelling

Answer 26

Hormones (Parathyroid, calcitonin)
Paracrines (cytokines)

Question 27

How can bone remodelling be identified in picture

Answer 27

Reversal lines:
Scalloped edge shows where bone resorption changes to bone deposition

Question 28

When does tooth movement (remodelling ofsoft and hard tissues) occur

Answer 28

• during eruption​
• post-eruptive (e.g. mesial drift)​
• orthodontic forces

Question 29

What is cartilage

Answer 29

Semi-rigid, unmineralised connective tissue​

Matrix is similar to bone:​
-Ground substance​
-Fibres

Question 30

What are the types of cartilage and where can they be found

Answer 30

Hyaline cartilage​
-Widespread​
-Larynx, nasal septum, trachea, ends of ribs (costal cartilages), articular surfaces, embryonic skeleton (precursor to bone)​

Fibrocartilage​
-Intervertebral discs, pubic symphysis​

Elastic cartilage​
-External ear, epiglottis, Eustacian tube

Question 31

What is the most common cartilage

Answer 31

Hyaline cartilage

Question 32

What produce cartilage cells

Answer 32

Chondroblasts

Question 33

Are there blood vessels in cartilage

Answer 33

No (avascular)

Question 34

Where are channels found in cartilage

Answer 34

Within thick areas

Question 35

What are the types of bone growth

Answer 35

Endochondral ossification (‘Long’ bones)
-Cartilage precursor​
-Cartilage proliferation​
-Cartilage replaced with bone​

Intramembranous ossification​ (‘Flat’ bones)
-Bone formed de novo in C.T.​
-No cartilage precursor

Question 36

What type of bone growth occurs in the skull

Answer 36

Intramembranous ossification

Question 37

How does endrochondral ossification work

Answer 37

Initially, a cartilage skeleton is laid down.
The cartilage is replaced with bone.
There are several centres of ossification.

Question 38

Where does cartilage proliferation occur

Answer 38

At the epiphyses

Question 39

What stages does the cartilage go through to reach the final process of osification

Answer 39

Ossifying cartilage
Hypertrophic zone
Proliferative zone
Resting zone

Question 40

What bone in the skeleten has a mixture of both types of bone growth

Answer 40

Base of the skull
Spheno-occipital synchondrosis
Cartilaginous joint that lies between the body of the sphenoid bone anteriorly and the basilar part of the occipital bone posteriorly

Question 41

What is achondroplasia

Answer 41

A genetic defect of cartilage growth
Endochondral bone growth is impaired. Intramembranous bone growth is unaffected.

Question 42

What type of bone growth develops the condyle

Answer 42

Endochondral bone growth

Question 43

What parts of the mandible change shape during aging

Answer 43

Coronoid process (disappears)
Alveolar process (as teeth are lost it is resorbed)
Angular process (reduces)