Vertebral Column - development Flashcards Preview

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Flashcards in Vertebral Column - development Deck (36):
1

Origin of CNS

Ectoderm

2

Primitive axis of embryo giving rigidity

Notchord

3

Notochord role

1. Forms the mesenchymal axial skeleton
2. Induces ectoderm to form neural fold

4

When does neural folding occur

Day 19 to 21 (complete neural tube)

5

Where and where do somites develop from

Axial mesoderm - at week 4 they arrange around neural tube

6

Somites function

Divide into 3 layers:
- Anterior (Dermatome)
- Middle (Myotome)
- Posterior (Sclerotome)

7

Dermatome becomes

The dermis - spreads out under ectoderm

8

Sclerotome will form

The spinal cord

9

Sclerotome definition

Region of bone and periosteum that is innervate by a single spinal nerve

10

Signalling molecules in response to which the sclerotome forms

BMP and Wnt - from ectoderm
Shh (Sonic Hedgehog) from notochord and neural tube floor plate

11

Sclerotome segmentation

Less dense areas contain intersegmental arteries

Dense areas caudally
and loose cranially

12

In absence of Shh

Vertebral column does not form

13

How do vertebral bodies form

Dense caudal part of sclerotome binds to cranial parts of adjacent s.

14

What and when has role in sclerotome segmentation

PAX1 - 7,8 week of development

15

Intervertebral disc formation and origin

Mesenchymal cells - between cephalic and caudal parts of scleroderm

16

What forms the nucleus pulposus

Notochord
disintegrates in front of vertebral bodies

17

Annulus fibrosus origin

sclerotome

18

Why are there more cervical nerves than vertebrae

Cranial part of C1 sclerotome fuses with O4

19

When do chondrification centres appear in vertebral bodies?

Week 6

20

Ossification of vertebrae - when and how many centres

up to 25th year
4 centres (each half of vertebral arch, and 2 in body)

21

Failure of ossification of VB

Wedge shaped vertebral body

22

Ribs origin

Costal processes of thoracic vertebrae
Synovial joints form to make union in thoracic region

23

Increase in height by age

□ 2nd year - 5cm/y
□ 2-7yo - 2.5cm/y
□ 7-puberty - 1.5cm/y
□ Puberty - 4cm/y

During puberty M gain 7-12cm, F gain 6-11cm

24

Growth complete in 99% at what age

M- 17
F - 15

25

Myotome forms

Muscles of back

26

Failure of chondrification centres to develop from mesenchyme

Hemivertebrae - lateral flexion (scoliosis)

27

Failure of ossification centres to develop

Wedge vertebrae - ant or post flexion

28

Grades of intervertebral disc degeneration

1 to 4
1 - age 15-40
2 - 35-70yo (brown pigment in NP)
3 - annulus bulges into nucleus + end plate damage
4 - severe; reduction in height and pigmentation, both end plates disrupted

29

Osteophytes

1st to 4th degree

Due to compressive forces outpouchings of vertebral body occur around its edges.

With time they can completely occlude the intervertebral disc
Number increases with age

30

Cauda equina syndrome cause

• Compression or trauma or tumour at L4/5 or L5/S1
Most commonly herniation

31

Cauda equina syndrome symptoms and epidemiology

• 40 and 50 years old - highest incidence

○ Symptoms:
§ Severe back pain
§ Saddle anaesthesia
§ Bladder and bowel dysfunction
§ Sciatica
§ Lower limb muscle weakness

32

Cauda equina nerves

Form sciatic n.
Compression will affect much of lower limb

33

Whiplash cause

RTA usually; Extension strain on neck and then secondary flexion

34

Whiplash symptoms

neck and shoulder pain, dizziness, headache, blurred vision

35

Whiplash associated injuries

interspinous ligament tears, spinous process fractures, disc rupture, rupture of the ligamentum flavum, facet joint disruption, stretching of the anterior muscles

36

Whiplash Associated Disorder

○ Pain, dizziness
○ Visual and auditory disturbances
○ Photophobia
○ Fatigue
○ Cognitive difficulties; concentration, memory loss, anxiety and depression