2. Basic Embryology of the Vertebral Column

Question 1

What are the 3 layers of the embryo called?

Answer 1

ectoderm, mesoderm and endoderm

Question 2

Invagination of ectoderm along the primitive streak gives rise to what embryonic structure?

Answer 2

notochord

Question 3

What is the name given to the mesoderm that will give rise to the vertebral column?

Answer 3

paraxial mesoderm

Question 4

What does paraxial mesoderm give rise to that will form the vertebral column?

Answer 4

somites

Question 5

Name the areas of cellular differentiation formed within the somite.

Answer 5

sclerotome, dermatome and myotome

Question 6

What part of the somite will give rise to the vertebral column?

Answer 6

sclerotome

Question 7

List, in order, the names of the successive vertebral columns formed during development?

Answer 7

membranous, cartilaginous, skeletal or osseous

Question 8

Migration of sclerotomes to surround the notochord forms what developmental feature?

Answer 8

the perichordal blastema

Question 9

The periochordal blastema gives rise to what processes?

Answer 9

neural processes and costal processes

Question 10

What is the name of the artery located between adjacent perichordal blasternae?

Answer 10

intersegmental artery

Question 11

Cell proliferation within the perichordal blastema will result in what features?

Answer 11

a loose cranial sclerotomite and a dense caudal sclerotomite

Question 12

What forms between the sclerotomites of a perichordal blastema?

Answer 12

the intrasclerotomal fissure (fissure of von Ebner)

Question 13

What is the earliest embryonic feature that will identify the postion of the adult intervertebral disc?

Answer 13

the intrasclerotomal fissure (fissure of von Ebner)

Question 14

The union of a dense caudal sclerotomite and a loose cranial sclerotomite from adjacent perichordal blasternae gives rise to what feature?

Answer 14

the vertebral blastema

Question 15

What vessel will be identified adjacent to the vertebral blastema?

Answer 15

the segmental artery

Question 16

What is the name given to the replacement of mesoderm by cartilage?

Answer 16

chondrification

Question 17

Chondrification begins in which region of the embryonic vertebral column?

Answer 17

the cervical region

Question 18

What are the names given to the centers of chondrification within the vertebral blastema?

Answer 18

centrum center, neural arch center, transverse process center

Question 19

How many centers of chondrification typically appear in the vertebral blastema?

Answer 19

six…2 for the centrum, 2 for the neural arch, 2 for each transver process

Question 20

What is the earlies time that centers of ossificationappear in the cartilaginous vertebra?

Answer 20

During the 7th embryonic week

Question 21

What is the ratio of primaryt to secondary centers of ossification for a typical vertebra?

Answer 21

3 primary centers; 5 secondary centers

Question 22

What are the names of the primary centers of ossification for a typical vertebra?

Answer 22

centrum centers and neural arch centers

Question 23

What is the classification of the joint forming between primary centers of ossification?

Answer 23

cartilage synchondrosis/ampiarthrosis synchondrosis

Question 24

What are the names of the synchondroses forming between primary centers of ossification in the typical vertebra?

Answer 24

neurocentral synchondrois and neural arch synchondrosis

Question 25

What are the names of the 5 secondary centers of ossification for a typical vertebra?

Answer 25

tip of the transverse process, tip of the spinous process, epiphyseal plate centers

Question 26

How many secondary centers of ossification appear in a typical vertebra?

Answer 26

five…1 for the tip of each transverse process, 1 for the tip of the spinous process, 1 for each epiphyseal plate

Question 27

What is the classification of the joint forming between secondary centers of ossification and rest of the typical vertebra?

Answer 27

cartilage synchondrosis/ampiarthrosis synchondrosis

Question 28

What are the names of the synchondroses forming between secondary centers of ossification and the rest of the typical vertebra?

Answer 28

tip of the transverse process synchondrosis, tip of the spinous process synchondrosis, and epiphyseal ring synchondrosis

Question 29

What is the range of apearance for secondary centers of ossification of a typical vertebra?

Answer 29

during puberty, typically ages 11-16 years old