DEVELOPMENT OF THE VERTEBRAL COLUMN

Question 1

forms a block-like structure on

either side of the neural tube?

Answer 1

Sclerotome of each somite

Question 2

Each block has a ?

Answer 2

• Each block has a ‘Cranial’
segment (loosely arranged
cells)
• & a ‘Caudal’ segment ( more
condensed tissue).

Question 3

It occurs when the caudal half of
the sclerotome above grows
down & fuses with the cephalic
half of the sclerotome below.

Answer 3

Resegmentation

Question 4

the body/centrum of each

vertebra is formed by ?

Answer 4

combination of the caudal half
of the somite above and the
cranial half of the somite below .

Question 5

Outcomes of Resegmentation?

Answer 5

1. the myotomes bridge the
   intervertebral discs.
2. The intersegmental arteries,
   at first lying between the 2
   sclerotomes, now trapped
   with in the vertebral bodies.

3. Spinal nerves come to lie
near the intervertebral discs
and leave the vertebral
column through the
intervertebral foramina.

Question 6

??? between the caudal & cephalic parts of the original

sclerotome segment do not proliferate

Answer 6

Mesenchymal cells

Question 7

fill the space between two

precartilaginous vertebral bodies? And form?

Answer 7

Mesenchymal cells /Intervertebral disc.

Question 8

The notochord regresses entirely in the region of the?

Answer 8

vertebral bodies

Question 9

The notochord regresses entirely in the region of the vertebral bodies , it
persists and enlarges in the region of the intervertebral disc and forms
the???

Answer 9

Nucleus Pulposus

Question 10

Fate of Notochord

In the region of the bodies of
vertebrae: ?

Answer 10

degenerates

Question 11

Fate of Notochord
Between bodies of vertebrae:
?

Answer 11

It forms the central part,
’Nucleus Pulposus’ of the
intervertebral discs

Question 12

Fate of Notochord

part of the
intervertebral discs  is formed
by the mesoderm surrounding
the notochord.
?

Answer 12

Annulus fibrosus

Question 13

As the vertebrae form, two primary curves of the spine are established:
?

Answer 13

• thoracic curvature • sacral curvature.

Question 14

Later on in postnatal life, two secondary curves are established:
?

Answer 14

• cervical curvature, as the child learns
to hold up his head and • lumbar curvature, forms when the
child learns to walk.

Question 15

lateral curving of the spine?

Answer 15

Scoliosis

Question 16

What happens in Scoliosis?

Answer 16

Scoliosis (lateral curving of the spine). • it is fairly common to have
two successive vertebrae fuse asymmetrically or have half a vertebra missing.

Question 17

What happens in Klippel–Feil Syndrome ?

Answer 17

In this case, the cervical
vertebrae are fused
causing reduced mobility
and a short neck.

Question 18

It is one of the serious type of vertebral column defects. It results from the imperfect fusion
or complete Non-fusion of the two halves of vertebral arches?

Answer 18

Spina Bifida/Cleft Vertebra:

Question 19

What is Spina Bifida Occulta?

Answer 19

– There is mal-development of the vertebral arch only and the spinal cord is intact.
– The bony defect is covered by skin.
– No neurological deficits present.
- complete Non-fusion of the two halves of vertebral arches.

Question 20

Spina bifida cystica

Explain ?

Answer 20

A more severe abnormality in which the neural tube fails to close, as a result, the
vertebral arches fail to form, and neural tissue is exposed. Any neurological deficits
depend on the level and extent of the lesion.

-imperfect fusion