Biomechanics of the vertebral body; trabeculae, cortical thickness and end plate

Question 1

C3-C7 are wider where?

Answer 1

transversely than anteroposteriorly

Question 2

They have a convex inferior surface and concave superiorly due to what?

Answer 2

the unicate process protruding upwards on the lateral borders

Question 3

what does the atlas lack?

Answer 3

a vertebral body or spinous process

Question 4

instead of a vertebral body to act as the weight bearing structure what does the atlas have?

Answer 4

lateral masses

Question 5

in relation to the atlas what is on the lateral masses?

Answer 5

the transverse articular surfaces in which the atlas connects with the cranium via the occipital condyles

Question 6

what is the strongest of the cervical vertebrae?

Answer 6

axis

Question 7

what does the axis allow?

Answer 7

pivoting movement of the head due to its unique structure

Question 8

what are the types of bone making up the lumbar vertebrae and what do they allow?

Answer 8

Outer cortical bone shell
Large section of cancellous bone deep to this.
Cancellous bone allows for dynamic compression where the cortical bone would just fracture if it alone was exposed to this

Question 9

what are the trabecular systems surrounded by?

Answer 9

compact bone

Question 10

bone is what?

Answer 10

hard and resilent

Question 11

what is bone composed of?

Answer 11

65% mineral salts
23% collagen
10% water
2% non-collagen proteins

Question 12

what is surrounding the bone?

Answer 12

a periosteum outer-layer; fibrous and osteogenic

Question 13

cortical bone is what?

Answer 13

relatively dense and compact

Question 14

in vertebrae what does cortical bone form?

Answer 14

a surrounding shell, around the trabecular bone

Question 15

what is the main role of cortical bone?

Answer 15

provide strength

Question 16

what does cortical bone contain?

Answer 16

osteon around haversian canals, give space for blood vessels and nerves

Question 17

what is the functional unit of trabecular bone?

Answer 17

trabeculae

Question 18

what is trabecular bone?

Answer 18

vertebral body core

Question 19

trabeculae form what?

Answer 19

interconnected, open porous network

Question 20

what are the pores filled with in trabecular bone?

Answer 20

bone marrow and blood vessels

Question 21

what does trabecular bone lack?

Answer 21

haversian canals

Question 22

where does trabecular bone get its nutrients?

Answer 22

via diffusion from bone marrow

Question 23

what is the main role of trabecular bone?

Answer 23

transfer mechanical force

Question 24

characteristics of cortical bone?

Answer 24

harversian systems, denser, compact, surrounding shell, heavy, provide strength

Question 25

characteristics of trabecular bone?

Answer 25

lacks haversian canals, more surface area, porous (3D network), core, lighten bone, transfer forces

Question 26

weight of the body produces what?

Answer 26

an axial compressive force on the vertebral column

Question 27

what percentage of weight is transferred to trabecular bone in the vertebral body?

Answer 27

25%-90%

Question 28

what vertebrae are under most stress?

Answer 28

thoracocolumbar and lower lumbar region

Question 29

anterior flexion of the trunk does what to the COG?

Answer 29

shifts the COG forward and creates shearing forces on the vertebrae

Question 30

to maintain anterior flexion of the trunk what is happening?

Answer 30

erector spinae muscles are acting to counteract and stabilise this movement, in doing so they are exerting a compressive force on the vertebrae

Question 31

what is wolffs law?

Answer 31

bone function changes cause bone structure modification

Question 32

limitations of wolffs law?

Answer 32

Fails to account for hormonal activity governing the activity of osteoclasts and osteoblasts in defining bone density To combine hormonal influences and mechanical forces as stress on bone the Mechanostat theory and Utah Paradigm was formed.

Question 33

in areas of stress, trabecular bone reacts in what ways?

Answer 33

Areas with most stress develop more dense trabeculae Thicker trabeculae Closer more uniform spacing of trabeculae Along areas of stress trabecular patterns form as a direct function of stress

Question 34

where is the vertical system found?

Answer 34

the vertebral column with the exception of the IV discs

Question 35

what is the vertical system composed of?

Answer 35

large cylindrical struts of trabecular bone in vertical arrangement in the central zone of the vertebral body

Question 36

what is the functional role of the vertical system?

Answer 36

to resist acial compression for weight bearing

Question 37

what does the vertical system resist?

Answer 37

shocks and jars perpendicular to the vertebral column

Question 38

the vertical system has the most resistance to what?

Answer 38

atrophy out of the trabecular systems

Question 39

what are the primary systems?

Answer 39

vertical system

Question 40

what are the secondary systems?

Answer 40

horizontal and oblique systems

Question 41

how many oblique systems are there?

Answer 41

4, 2 superior, 2 inferior

Question 42

what to oblique systems resist?

Answer 42

torsion, they are woven together

Question 43

oblique systems along with vertical resist what?

Answer 43

bending and shear

Question 44

horizontal systems resist what?

Answer 44

muscular tension produced to counteract movements

Question 45

superior oblique runs where?

Answer 45

runs from superior articular process through pedicle to lower surface of the vertebral body

Question 46

inferior oblique runs where?

Answer 46

runs from inferior articular process through pedicle to upper surface of the vertebral body

Question 47

oblique systems absent where?

Answer 47

in anterior surface of vertebral body making it more prone to fracture

Question 48

the vertebral body is made up of what?

Answer 48

a shell of cortical bone with an inner core of cancellous bone

Question 49

a solid block of cortical bone is likely to what?

Answer 49

to fracture along cleavage planes when dynamic force is applied to it.

Question 50

without the addition of cancellous bone in the centre the cortical bone would be what?

Answer 50

be a shell which is also likely to collapse when force is applied.

Question 51

the cancellous bone forms what?

Answer 51

vertical and transverse trabeculae which act as the internal architecture of the bone. They form ‘cross beam’ like structures meaning tension is held both transversely and vertically in the vertebral body.

Question 52

the strength of a vertebral body is dependent on what 4 factors?

Answer 52

bone mass, the trabeculae architecture, the size of the vertebral body and the thickness of the cortical ring.

Question 53

which spine has the largest thickness?

Answer 53

lumbar spine (290um)

Question 54

what is the second largest thickness of spine?

Answer 54

cervical spine (285um)

Question 55

what thickness is the thoracic spine?

Answer 55

244um

Question 56

the vertebral bodies cortical shell is thicker where?

Answer 56

anteriorly thicker and thinner posteriorly

Question 57

is the cartilagenous end plate thick or thin?

Answer 57

very thin; 1mm

Question 58

how thick is the IVD?

Answer 58

7-10 mm

Question 59

where is the CEP thinnest?

Answer 59

in the central region adjacent to the nucleus pulposus

Question 60

what does the CEP contain?

Answer 60

osseous component and a hyaline cartilage and cartilaginous component

Question 61

what is the function of the CEP?

Answer 61

maintaining the integrity of the vertebral bodies

Question 62

what does the CEP absorb?

Answer 62

Simultaneously absorbs hydrostatic pressure that results from mechanical loading of the spine

Question 63

what does the CEP prevent?

Answer 63

Prevent the highly hydrated nucleus from bulging into the adjacent vertebral bone

Question 64

the CEP degenerates with what?

Answer 64

Degenerates with ageing- calcification