Bone + Cartilage

Question 1

What are the 2 bone types?

Answer 1

1. Cortical, compact bone

2. Cancellous, spongy bone

Question 2

Compare the 2 different MACROSCOPIC bone types (4)

Answer 2

CORTICAL

• Dense, outer plate
• 8-85% of the skeleton

CANCELLOUS, SPONGY BONE

• Internal trabecular scaffolding
• 15-20% of skeleton

Question 3

What is the alveolar bone?

Answer 3

The part of the mandibular and maxillary bone which surrounds the teeth and forms the tooth sockets

Question 4

Does cortical bone contain BVS?

Answer 4

YES

Cortical bone has nutrient canals that contain BV’S

Question 5

What is the composition of bone by weight (3)

Answer 5

1. 60% inorganic
2. 25% organic
3. 15% water

Question 6

What makes up the inorganic portion of bone?

Answer 6

Hydroxyapatite

Question 7

What makes up the organic portion of the bone?

Answer 7

• Collagen (90%)
• Glycoproteins
• Proteoglycans

Question 8

What 2 ways can bone be resorbed around the tooth? (2)

Answer 8

1. Whole alveolar bone can come as one part

2. Or part of the bone is resorbed

Question 9

What makes up the extracellular matrix (2)

Answer 9

1. Ground substance (semi-fluid gel)
2. Fibres (reinforce extracellular ground substance)
   - Collagen
   - Elastin

Question 10

What are the 2 different MICROSCOPIC bone types

Answer 10

1. Woven bone

2. Lamellar bone

Question 11

Compare the 2 different MICROSCOPIC bone types

Answer 11

WOVEN BONE:

• Rapidly laid down
• Irregular disposition of collagen
• For fracture repair (callus)
• Contains many osteocytes

LAMELLAR BONE: (more organised)

• Laid down more slowly
• Collagen fibres laid down in parallel
• Normal form in adult
• Contains fewer osteocytes

Question 12

What type of bone is found in a fractured bone?

Answer 12

Areas of woven bone

Question 13

What type of bone is found in an original bone?

Answer 13

Lamellar bone

Question 14

Following orthodox tx, what bone can be MORE present?

Answer 14

MORE woven over lamellar

Question 15

Describe the structure of cortical/compact bone (5)

Answer 15

1. Laid down in lamellar bone
2. Forms longitudinal columns
3. Organised in Haversian systems around central canal
4. Lateral (volkmans) canals

CANALS contain BV’s

Question 16

Describe the structure of cancellous bone (6)

Answer 16

1. Network of thin trabeculae
2. Trabeculae consist of lamellae
3. Osteocytes present
4. No obvious Haversian systems
5. The bone is thin, and nutrients can diffuse in
6. The spaces between the trabeculae are filled with bone marrow

Question 17

What are osteoblasts derived from?

Answer 17

Mesenchymal stem cells

Question 18

Function of osteoblasts

Answer 18

Synthesise + secrete collagen fibres to form a matrix

Question 19

What is the matrix (formed by osteoblasts) mineralised by?

Answer 19

Calcium salts

Question 20

What are osteocytes?

Answer 20

Osteoblasts that become trapped in mineralised bone

Question 21

Where are osteoblasts found?

Answer 21

They lie on the surface of bone

Question 22

Where are osteocytes found?

Answer 22

They lie within the spaces (lacunae)

Question 23

Function of osteocytes? (2)

Answer 23

1. They contact other osteocytes via cytoplasmic processes that run in canaliculi
2. Appear to communicate with osteoblasts

Question 24

State the type of arrangement present in osteocytes

Answer 24

Radicular arrangement

Question 25

What are osteoclasts?

Answer 25

Large multinucleate cells, derived from haemopoietic stem cells

Question 26

Function of osteoclasts

Answer 26

Resorb bone (acid phosphatases)

Question 27

Where are osteoclasts found?

Answer 27

They lie in concavities in the bone (Howships lacunae)

Question 28

Define bone remodelling

Answer 28

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

Question 29

What is the bone remodelling process regulated by? (2)

Answer 29

- Hormones (e.g. PTH + calcitonin) | - Parcines (various cytokines)

Question 30

When do tooth movements occur? (3)

Answer 30

1. During eruption 2. Post-eruptive (e.g. messiah drift) 3. Ortho forces

Question 31

Describe cartilage structure

Answer 31

Semi-rigid, unmineralised connective tissue

Question 32

What are the different types of cartilage? (3)

Answer 32

1. Hyaline cartilage 2. Fibro cartilage 3. Elastic cartilage

Question 33

Where is hyaline cartilage found? (3)

Answer 33

1. Larynx 2. Nasal septum 3. Trachea

Question 34

Where is fibrocartilage found?

Answer 34

1. Invertebral discs | 2. Pubic symphysis

Question 35

Where is elastic cartilage found?

Answer 35

1. External ear 2. Epiglottis 3. Eustacian tube

Question 36

What forms chondrocytes?

Answer 36

Chondroblasts that get trapped in the matrix become chondrocytes

Question 37

Are cartilage cells (chondrocytes) vascular?

Answer 37

NO

Question 38

What stores do chondrocytes contain? (2)

Answer 38

Stores of lipid and glycogen

Question 39

What are the types of bone growth?

Answer 39

1. Endochondral ossification - Long bones - Cartilage precursor 2. Intramembranous officiation - Flat bones - No cartilage precursor

Question 40

Define achondroplasia

Answer 40

A genetic defect of cartilage growth | Associated with limited growth on the sphenoid-occipital synchondrosis

Question 41

What type of arrangement does condylar cartilage have?

Answer 41

Endochondral arrangement

Question 42

When does the TMJ rearrange itself?

Answer 42

Disc and condyle changes shape as we are born and grow and lose teeth

Question 43

What makes up the TMJ histological structure?

Answer 43

1. Articular disc 2. Articular zone 3. Proliferative zone 4. Fibrocartilaginous zone 5. Calcified cartilage 6. Subarticular bone

Question 44

What 3 areas of the mandible have an important role in remodelling?

Answer 44

1. Coronoid process 2. Alveolar process 3. Angular process