Bones

Question 1

What are the 5 bone types?

Answer 1

1. Long
2. Short
3. Irregular
4. Flat
5. Sesamoid

Question 2

Basic bone structure of a long bone (top to bottom)

Answer 2

Epiphysis
Metaphysis
Diaphysis
Metaphysis
Epiphysis

Question 3

2 types of tissue in a bone? and characteristics

Answer 3

Compact bone is dense and is designed to withstand large amounts of compressive force.
Spongy bone has open spaces, it is supportive but also light in weight. designed to be ready for breakdown and remodeling by osteoclasts/blasts.

Question 4

That sheath like structure surrounds the bone?

Answer 4

Periosteum

Question 5

What us the medullary cavity?

Answer 5

The medullary cavity is the hollow part of bone that contains bone marrow.

Question 6

What is an osteon?

Answer 6

The osteon consists of a central canal called the osteonic (haversian) canal, which is surrounded by rings called concentric lamellae. Lamellae are perpendicular to each other in order to resist twisting forces in multiple directions. Between the rings of matrix, the bone cells (osteocytes) are located in spaces called lacunae.

Question 7

What runs down the center of an osteon?

Answer 7

Central canals contain blood vesicles, nerves and lymphatic vesicles which branch off at right angles through a perforating canal extending out to the periosteum and the endosteum.

Question 8

What are the periosteum and the endosteum?

Answer 8

Thin layers of membrane of connective tissue that lines the inner surface of the medullary cavity of long bones.
The endosteum is also the lining of the central canal of the osteon allowing remodeling of osteons over time.

Question 9

What is an osteocyte

Answer 9

Bone (osteo) cell (cyte)
Located in lacuna (spaces in the lamellae)
has canaliculi branching off connecting to other lacunae and with the central canal they can send nutrients to be transported into the osteocytes and waste transported out.

Question 10

what is trabeculae?

Answer 10

The main product of spongy bone. They may look like a random structure where it in fact it forms along lines of stress to transport force to the compact bone

Question 11

Why is spongy bone honeycombed in structure?

Answer 11

In order for the muscles to move it easier

Question 12

Functional differences of bone types?

Answer 12

Compact 
Compact bone like a drinking straw
Good at absorbing/transmitting forces in single 
direction
Heavy

Spongy
Spongy absorb forces from multiple directions
Found where little force absorption or force from
many directions
Light weight
Support and protection for bone marrow cells

Question 13

Bone matrix: 3 major components of bone and their approximated percentage?

Answer 13

Calcium phosphate 66% of total bone mass
Collagen fibres 33%
Bone cells 2%

Question 14

Calcium phosphate

Answer 14

• Forms hydroxyapatite (naturally occurring mineral form of calcium apatite) through interaction with calcium hydroxide
• Bind calcium carbonate, sodium, magnesium, fluoride
• Provides compression strength

Question 15

Collagen fibres

Answer 15

• Provides tensile strength

Question 16

Bone cells

Answer 16

• Maintain the bone matrix

Question 17

4 types of bone cells?

Answer 17

Osteoclasts
• Break down bone matrix
• Osteolysis

Osteoblasts
• Produce new bone substance
• Osteogenesis

Osteocytes
• Mature bone cells

Osteoprogenitor cells
• Mesenchymal cells
• Differentiate into osteoblasts
• Important in fracture & repair

Question 18

5 characteristics of bone remodeling

Answer 18

• Normal process/constantly occurring
• Maintains structural integrity (strength)
• Balance of reabsorption and formation important
• Mechanism for shape change over time
• Remodel after a bony injury

Question 19

What are factors that affect bone remodeling?

Answer 19

Dietary factors
• Calcium & phosphate
• Magnesium, citrate, carbonate & sodium
• Vit A, C & D

Hormonal factors
• Parathyroid hormone
• Calcitonin
• GH & thyroxine
• Sex hormones (estrogen & testosterone)

Strain
• Loading through activity/exercise (or lack thereof)
• Magnitude, rate and direction
• Influenced by activity type
• Immobilisation

Aging

Gender
• Hormonal factors (post-menopausal)

Question 20

4 markers of bone strength

Answer 20

Bone mineral density (BMD)
Bone mineral content (BMC)
Size
Geometry

Question 21

How is bone density measured?

Answer 21

Dual energy X-ray absorptiometry scan (DEXA or DXA)

Quantitative computed tomography (QCT)

Question 22

What does different bone types look like in a DEXA scan?

Answer 22

Compact looks white and more solid whereas spongy bone looks grey and dull as it is less dense.

Question 23

What information does a DEXA scan provide?

Answer 23

A detailed image on the scanned bone as well as detailed information of various tissues within the scanned areas such as fat mass, lean mass, fat percentage BMI score and BMC.

Question 24

How are DEXA scans are compared?

Answer 24

Compared to young norms, compared with results of people with the same gender and race. This is how t scores are determined.

Question 25

In regard to a DEXA scan what is a t score?

Answer 25

T score expresses the bone density in terms of standard | deviations below peak young adult bone mass. like averages and percentiles.

Question 26

Using t scores how can you tell someone is at risk of osteoporosis?

Answer 26

-3 -2 -1 0 1 2 3 1 to -1: normal -1 to -2.5: at risk of osteoporosis and low to medium fracture risk -2.5 or lower: osteoporosis = fracture risk is high

Question 27

What does QCT scan provide?

Answer 27

A calibrated references to materials of known density to compare the density of structures. A more portable options for limbs. 3D image reconstruction BMD and geometry Trabecular & compact bone individually unlike DEXA scans.

Question 28

What is bone in the bank?

Answer 28

Start exercising at a young age in order to build up bone before you stop building bone during adulthood.

Question 29

10 acute fracture types

Answer 29

``` Greenstick Transverse Oblique Spiral Avulsion displaced 1 compound 2 comminuted Growth plate fracturing Epiphyseal Slippage (capital femoral) ```

Question 30

2 types over use fractures +def

Answer 30

Periostitis (medial tibial stress syndrome) Stress fracture caused by repetitive forces without an appropriate time to heal.

Question 31

Greenstick fracture characteristics

Answer 31

Tends to occur during growth. Breaks like a green branch (greenstick). Partial break through the bone which is not fully calcified.

Question 32

Transverse fracture characteristics

Answer 32

Full break with a straight line going all the way across.

Question 33

Oblique fracture characteristics

Answer 33

straight line on an angle of a long bone.

Question 34

Spiral fracture characteristics

Answer 34

Twists around the bone shaft. Created from twisting force

Question 35

comminuted fracture characteristics

Answer 35

Fracture into 2 pieces causing multiple bone fragments throughout tissue.

Question 36

Compound fracture characteristics

Answer 36

When the bone breaches the skin

Question 37

What are displaced fractures?

Answer 37

Compound and comminuted

Question 38

Avulsion fracture characteristics

Answer 38

Where the part of the bone is broken off at the attachment site of the tendon or ligament.

Question 39

Growth plate fracture characteristics

Answer 39

Can cause deformities as other bones are growing yet this bone is too busy healing.

Question 40

Epiphyseal Slippage (capital femoral) fracture characteristics

Answer 40

A specific type of growth plate fracture where the head of the femur becomes displaced relative to the neck of the femur.

Question 41

Periostitis (medial tibial stress syndrome) characteristics

Answer 41

Shin splints | occur during high impact sports and running

Question 42

Stress fractures characteristics

Answer 42

Not giving injuries enough time to heal causes stress fractures to occur.