Basic Bones

Question 1

What are accessory bones?

Answer 1

Bones present in ancestral form
Can be mistaken for fractures
Bone not normally present in body, but present in some members of the population

Question 2

What is achondroplasia?

Answer 2

Dominant mutant allele
Chondrocytes in metaphysis fail to multiply and enlarge
Long bones fail to enlarge, other bones unaffected

Question 3

What is the axial skeleton?

Answer 3

Skull, vertebrae, ribs, sternum

Question 4

What is the appendicular skeleton?

Answer 4

Limbs, limb girdles

Question 5

What is cancellous bone?

Answer 5

‘Spongy’ bone within cortical shell

Supports bone marrow

Question 6

What is cortical bone?

Answer 6

Hard layer of bone surrounding cancellous bone

Synonymous with compact bone

Question 7

What is the diaphysis?

Answer 7

Forms the shaft of long bones

Question 8

What is the endosteum?

Answer 8

Lines medullary cavities in long bones

Osteogenic

Question 9

What is the epiphysial growth plate?

Answer 9

Interface between epiphysis and metaphysis
Cartilage made at epiphysial growth plate ossified at metaphysis
When fully developed, only articular cartilage remains

Question 10

What is the epiphysis?

Answer 10

Forms the distal and proximal ends of bones

Can be pressure, traction epiphysis

Question 11

Pressure epiphysis

Answer 11

Region of a long bone that forms articular surface

Question 12

Traction epiphysis

Answer 12

Region of a long bone where tendon, ligament attaches

Question 13

Elastic cartilage

Answer 13

Flexible, can be bent without damage

In epiglottis, pinnae

Question 14

Fibrous cartilage

Answer 14

Can be compressed

Between vertebrae

Question 15

Hyaline cartilage

Answer 15

On articular surface of bones

Forms precursor to skeletal system

Question 16

What is a long bone?

Answer 16

Bone with a shaft, proximal and distal ends

Question 17

Medullary cavity

Answer 17

Cavity within bones.

Contains bone marrow - can be yellow or red

Question 18

Metaphysis

Answer 18

Part of diaphysis
Adjacent to epiphysis
At each end of a growing bone
Site of remodelling, high metabolic activity

Question 19

Nutrient artery

Answer 19

Delivers nutrients, bone cells to cartilage model
Initiates ossification at primary site
Inserts into the nutrient foramen

Question 20

Location of nutrient foramen

Answer 20

Cartilage skeleton, developing bones

Normally in the middle of developing bone

Question 21

Osteoblasts

Answer 21

Cells that produce bone

Question 22

Osteoclasts

Answer 22

Cells that break down, remodel bone

Question 23

Pneumatic bones

Answer 23

Hollowed bones
Reduce weight of what would otherwise be a heavy bone
EG: sinuses in skull

Question 24

Periosteum

Answer 24

Lines exterior of cotrical bone
Very vascularised, innervated
Outer fibrous layer
Inner osteogenic layer

Question 25

Sesamoid bones

Answer 25

Lie within a tendon | Sesame-seed shaped

Question 26

Trabecular bone

Answer 26

Synonymous with cancellous bone | Good at resisting static force

Question 27

``` Standard structure of a bone 1) 2) 3) 4) ```

Answer 27

1) Cancellous bone surrounded by cortical bone 2) Bone marrow is within medullary cavity of cancellous bone 3) Cortical bone surrounded by periosteum exteriorly, endosteum interiorly. 4) Periorsteum and endosteum are osteogenic

Question 28

Two broad types of ossification

Answer 28

Intermembranous ossification Endochondral ossification

Question 29

Example of intermembranous ossification

Answer 29

Skull formation

Question 30

``` Skull formation 1) 2) 3) 4) ```

Answer 30

1) Skull initially 1 cell thick 2) Cortical bone forms 3) Cancellous bone forms in between 4) Anterior fontanelle closes ~ 18 months

Question 31

Fontanelle

Answer 31

Area of skull not fully developed, to allow foetal skull to change shape in birth canal

Question 32

Endochondral ossification 1) 2)

Answer 32

1) Hyaline cartilage precursor to skeletal system | 2) Bone first appears ~6-8 weeks of life

Question 33

Primary centre

Answer 33

Where bone first appears

Question 34

Where does bone first appear when developing?

Answer 34

In middle of shaft. | Extends from middle to extremeties

Question 35

How does ossification begin?

Answer 35

Blood vessels induce osteoprogenitor cells (mesoderm) to become osteoblasts

Question 36

When do the periosteal and endosteal layers form?

Answer 36

Simultaneously

Question 37

How do the diaphysis, epiphysis and metaphysis form bones?

Answer 37

Diaphysis forms shaft of bone Epiphysis forms ends of bone Metaphysis ossifies chondrocytes fed through it by the epiphysial growth plate

Question 38

What are secondary epiphysial centres?

Answer 38

Signify that growth is still occurring Can be confused with a fracture If damaged, can prevent growth

Question 39

``` Blood supply to developing bones 1) 2) 3) 4) ```

Answer 39

1) Nutrient 2) Periosteal (to exterior of shaft) 3) Metaphysial 4) Ephiphysial

Question 40

When does bone first appear?

Answer 40

First 6-8 weeks of life