development of spine

Question 1

explain development of the spine

Answer 1

• sclerotome cells of each level have right and left mass with notochord in middle
• Each mass has a light top portion and dense bottom portion
• eventually dense portion would move down and fuse with light portion one level below
• denser part will seperate from original mass and tvp will grow between two myotomal masses

Question 2

How do masses migrate to form around cord and what is ant and post make up

Answer 2

• both masses will begin to migrate anteriomediall and posteriorly medial

ant= centrum and body 
post= neural arch

Question 3

Hemi vertebrea

Answer 3

one side of sclerotome mass did not migrate to meet contralateral side

Question 4

Butterfly vertebrea

Answer 4

there is a migration and meeting in the middle but it doesnt fuse (incomplete centrum)

Question 5

Block vertebrae

Answer 5

incompletion of sclerotome masses (light and dense)

Question 6

What is klippel feil syndrome due to

Answer 6

hemivertebrae

Question 7

what type of bone formation is vertebrae

Answer 7

endochondral bone formation

Question 8

What are the primary ossification cenetrs

Answer 8

1 for centrum

2 for perichondral arches (R+L centrum, pedicals, lamina)

Question 9

What are the secondary ossification centers

Answer 9

2 for epipheseal rings
1 for Sp
1 for each TP

Question 10

What is scheurmas disease

Answer 10

secondary ossification centers fail to form properly

- congenital kyfosis( due to rims not forming)

Question 11

Spina bifida is due to

Answer 11

-primary ossification centers fail

perichondral centers fail to fuse in midline

Question 12

C1 developmet

Answer 12

3 primary ossification centers
1. in anterior arch
2 in lateral masses

centrum of c1 actually form dens of c1

Question 13

Agenesis of ant arch and post arch

Answer 13

each of the primary ossifications centers fail

secondary ossification could also fail on post tubercle

Question 14

5 stages of developement of dens

Answer 14

1. two primary centers of ossification in dens
2. fuse at midline at 8m developmet
3. developing dens fuses to body at 6y/o
4. a secodary ossification at very tip appears b/w 3-6years old (ossiculum terminale)
5. Ot fuses with dens at 12y/o

Question 15

what is it called when OT doesnt fuse with dens

Answer 15

persistent ossiculum terminale

Question 16

what is it called when dens doesnt fuse to body

Answer 16

os odontodeum