1. vertebral column - evolution and development

Question 1

chordates

Answer 1

have a notochrod at some stage

Question 2

vertebrates

Answer 2

column develops in response to notochord signals

• notochrod exists before vertebral column
• most chordates dont have a vertebral column

Question 3

neotony

Answer 3

evolutionary process where juvenile characteristics are retained in the adult and passed on

Question 4

3 step process of vertebral development

Answer 4

1. mesenchymatous
2. cartilagenous
3. osseus

Question 5

mesenchymatous stage

Answer 5

undifferentiated mesoderm
sclerotome cells of somites migrate to form: 
1. perinotochordal sheath 
2. neural arch 
3. costal element

Question 6

body wall vessels from the aorta form

Answer 6

between the somites

Question 7

why do body wall vessels foorm between the somites

Answer 7

tissue is less dense there

Question 8

when does mesenchymatous stage occur

Answer 8

4-6 weeks

Question 9

vertebrae from in line with

Answer 9

the gap between 2 adjacent somites

Question 10

perinotochordal cells near body wall vessels

Answer 10

have better nutrition

• grow larger and will become cartilage (vertebral bodies)
• vertebral bodies form in line with the gap between adjacent somites
• each vertebra is formed from part of 2 adjacent somites = intersegmental

Question 11

1 invertebral muscle is from

Answer 11

1 somite

Question 12

why are vetebral bodies called intersegmental

Answer 12

because they form inbetween somites

Question 13

notochord once vertebral bodies are formed

Answer 13

squeezed into areas between vertebral bodies - intervertebral disks

Question 14

when does cartilagenous stage occur

Answer 14

6-9 weeks

Question 15

cartilagenous stage

Answer 15

centres of chrondrification

1. centrum
2. neural arches
3. costal

Question 16

annulus fibrosis

Answer 16

fibrocartilage that forms in circles arund the notochrodal remnant

Question 17

notochordal remnant

Answer 17

nucleus pulposus

Question 18

what happens when cartilage centres fail to form

Answer 18

doesnt stop the other sde from forming
causes vetebral asymmetry - hemivertebrae
can cause structural scoliosis

Question 19

when does osseous stage occur

Answer 19

8-10 weeks

Question 20

primary centres of ossification appear

Answer 20

centrum - unparied
neural arches
costal

Question 21

primary ossification centre in the centrum is

Answer 21

unpaired

Question 22

cartlage growth plates dont ossify until

Answer 22

6-8 years

Question 23

costal centres either

Answer 23

fuse with the rest of the vertebra or become ribs and develop joints (thorax only)

Question 24

what happens if there arent enough notochordal cells

Answer 24

block vertebra - too few notochrodal cells remaining, therefore there is not enough intervertebral disk
failure of segmentation
vertebra form together - may not happen simetrically, can cause formation of scoliosis

Question 25

what happens when there is too many notochrodal cells

Answer 25

butterfly vertebra too many notochordal cells remain notochord seems to inhibit bone failure of formation - middle of the vertebral body is much thinner

Question 26

vertebral elements

Answer 26

1. centrum element 2. neural arch element 3. costal element

Question 27

centrum element

Answer 27

central portion of vertebral bodies | does not make the whole vertebral body

Question 28

neural arch element

Answer 28

dorsal arch surrounds spinal cord zygapophyseal joints, mammillary processes contributes to lateral aspect of vertebral body

Question 29

costal element

Answer 29

forms ribs of the thorax, but in different regions it forms different features of respective vertebra not the gap between the costal and neural elements

Question 30

hox genes control

Answer 30

body segment features

Question 31

growth of the vertebral column by 6-8 years

Answer 31

the growth plates close, but the VB endplates and processes are still in cartilage ie. can still grow taller

Question 32

endplate

Answer 32

where vertebral bodies meet intervertebral discs

Question 33

growth of the vertebral column at puberty

Answer 33

secondary centres of ossification appear 1. spinous process 2. transverse process 3. ring apophysis processes continue to grow larger VBodies can continue to grow taller due to the ring epiphysis

Question 34

all epiphysis close at

Answer 34

adulthood | growht can only continue by surface remodelling (impacts surface area, not height)

Question 35

3 steps of the vertebral development process

Answer 35

1. mesenchymatous 2. cartilagenous 3. osseus

Question 36

mesenchyme is

Answer 36

undifferentiated mesoderm

Question 37

vertebral colum is developed from

Answer 37

sclerotome cells of somites

Question 38

sclerotomal cells of ssomites migrate to form

Answer 38

perinotochordal sheath neural arch costal element

Question 39

sclerotomal cells of somites migrate in which stage

Answer 39

mesenchymatous stage

Question 40

which cells are nearest to body wall vessels from the aorta in mesenchymatous stage

Answer 40

perinotochordal cells | have better nutrition because of this

Question 41

why are vertebral bodies called intersegmental

Answer 41

because they are formed from part of 2 adjacent somites

Question 42

why are myotomes segmental

Answer 42

1 intervertebral muscle is from 1 somite

Question 43

resegmentation

Answer 43

an entire somite splits | to explain how one vertebral body s formed by 2 somites

Question 44

mesenchyme is gradually replaced by

Answer 44

hyaline cartilage

Question 45

z-joints

Answer 45

zygapophyseal joints | connect neural arches to each other from one vertebra to the next

Question 46

does the centrum element make the whole vertebral body

Answer 46

no-the lateral portion is made by the nueral arch element

Question 47

mammillary process

Answer 47

tiny bump next to the z joint

Question 48

mammillary processes are from

Answer 48

neural arch elements

Question 49

in the thoracic, the transverse process is from

Answer 49

neural arch elements

Question 50

in the cervical, sacral and lumbar the transverse process is from

Answer 50

costal elements

Question 51

end plate is where

Answer 51

vertebral body meets the intervertebral disks | what allow us to grow in height

Question 52

secondary ossification centres

Answer 52

1. spinous process 2. transverse process 3. ring apophysis