Vertebral Column

Question 1

requirements of vertebrae

Answer 1

protection, weight bearing/ force transmission, mobility

Question 2

vertebrae vs intervertebral discs

Answer 2

24 mobile vertebrae

23 intervertebral discs - C! has no intervertebral disc

Question 3

How do requirements vary in different regions?

Answer 3

Lordosis in cervical & lumbar regions = more mobility, less stability
Kyphosis in thoracic & sacral = less mobility, more stability

Question 4

vertebral column motion segment consists of

Answer 4

3 joints, 2 vertebrae, 1 intervertebral disc, ligaments, muscles & nerves

Question 5

movements of vertebral column motion segment

Answer 5

flexion, extension, lateral flexion, axial flexion

usually involve a combination of rotation and translation components

Question 6

ring apophysis

Answer 6

secondary ossification centre that incorporates/fuses in the outer the annular fibrosis fibres into bone for secure attachment. Filled in is hyaline cartilage that is end plate

Question 7

bone of vertebral body consists of

Answer 7

outer shell cortical bone, inner trabecular bone & red bone marrow (gives ability to slightly compress)

Question 8

organisation of trabeculae in vertebral body

Answer 8

vertical trabeculae are stronger and thicker than the horizontal trabeculae (withstands more compression with the support of horizontal struts)

Question 9

what is the vertebral body able to resist

Answer 9

compressive forces (not translation or rotational forces)

Question 10

what does the nucleus pulposus consist of

Answer 10

• 90% water (incompressible)
• proteoglycans (thickness & viscosity)
• collagen (thickness & viscosity)

Question 11

what do the vertebral endplates consists of

Answer 11

• hyaline cartilage / fibrocartilage due to annular fibres

Question 12

what does the annulus fibrosis consist of

Answer 12

• collagen type 1 (largest, strongest, resist lengthening)

- 10-20 concentric fibres

Question 13

annulus fibrosis weakness

Answer 13

posterolateral corners concentric rings are incomplete

Question 14

orientation of annular fibres

Answer 14

65° angle to vertical

Question 15

when does disfunction in weight-bearing occur?

Answer 15

NP has dried out

stretching or tearing of AF fibres (leads to translation/ instability)

Question 16

which region has the lowest disc to vertebral body height? consequence?

Answer 16

thoracic region

less mobility

Question 17

what is the role of the intervertebral disc in resisting movement?

Answer 17

collagen fibres in annulus fibrosus resist tension

• distraction - all AF fibres resist
• translation - 50% AF fibres resist

Question 18

what movements can the intervertebral discs resist?

Answer 18

flexion, extension, lateral flexion

• compression of the AF will resist further movement, and tension on the opposite side, pressure deforms NP & creates further compression
• axial rotation - 50% of fibres limit excessive rotation

Question 19

4 posterior elements of vertebrae & function

Answer 19

1. lamina
2. articular process
3. spinous process
4. transverse process
   - muscle & ligament attachment
   - provide stability
   - guide movement

Question 20

how does the zygoaphyseal joint resist movement?

Answer 20

inferior articular processes hook onto the superior articular processes of the vertebra below

• depending on the ORIENTATION of the articular facets
• or the HEIGHT of the superior articular processes

Question 21

vertebral movements for spinal flexion

Answer 21

anterior rotation and anterior translation of the superior vertebrae on inferior vertebrae

Question 22

how does vertebral structure limit translation, extension & axial rotation

Answer 22

• translation is blocked due to processes and limits rotation due to the height of the process
• extension limited due to spinous process, ribs and disc height to body ratio
• axial rotation of the superior vertebra is limited by the superior articular facets alighted in the sagittal plane

Question 23

angle of zygapophysial joint in the cervical vertebra

Answer 23

almost coronal orientation
45° to transverse
allow all movements

Question 24

angle of zygapophysial joint in the thoracic vertebra

Answer 24

almost coronal orientation
60-80° to transverse
allow axial rotation & lateral flexion

Question 25

angle of zygapophysial joint in the lumbar vertebra

Answer 25

sagittal plane orientation vertical

allow flexion-extension

Question 26

how does pars interarticularis fracture occur

Answer 26

posterior weight bearing - under compression & extension, weight can be transferred through inferior articular processes to the lamina below
transfers weight bearing from inf art to lamina - pars interarticularis

Question 27

when does posterior weight bearing occur

Answer 27

occurs in extension & rotation/lateral flexion

Question 28

why is a pars interarticularis fracture bad?

Answer 28

separates anterior & posterior and limits support to translation/rotation
lumbar lordosis - L4/5

Question 29

spinal ligaments/structures that limit extension 3

Answer 29

1. anterior longitudinal ligament
2. anterior annular fibres
3. compression posteriorly

Question 30

spinal ligaments/structures that limit flexion 5

Answer 30

1. interspinous ligament
2. posterior longitudinal ligament
3. ligamentum flavum (not much)
4. supraspinous ligament
5. fascia and muscles

Question 31

interspinous ligaments - orientation, purpose

Answer 31

oblique fibre orientation
anterior/inferior

resists posterior translation
keeps the Z joints in place to maintain stability
during flexion - combine anterior rotation with anterior translation, keeps z joints in contact, resist posterior shear of superior vertebra