Embryology of the Vertebral Column

Question 1

When does the embryonic disc form?

Answer 1

second week in utero

Question 2

When does gastrulation occur or a 3-layered embryo form?

Answer 2

third week in utero

Question 3

What are the 3 layers of the embryo called?

Answer 3

ectoderm, mesoderm, and endoderm

Question 4

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

Answer 4

notochord

Question 5

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

Answer 5

paraxial mesoderm

Question 6

What embryonic structure gives rise to the somites?

Answer 6

paraxial mesoderm

Question 7

Somites are separated from one another by what embryonic feature?

Answer 7

intersegmental fissures

Question 8

Name the areas of cellular differentiation formed within the somite.

Answer 8

sclerotome, myotome, and dermatome

Question 9

What are the names of successive vertebral columns formed during development?

Answer 9

membranous, cartilaginous, skeletal or osseous

Question 10

Migration of a somite pair to surround the notochord forms what developmental feature?

Answer 10

the perichordal blastema

Question 11

The perichordal blastema gives rise to what processes?

Answer 11

neural processes and costal processes

Question 12

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

Answer 12

intersegmental artery

Question 13

What forms between the sclerotomites of a perichordal blastema?

Answer 13

the intrasclerotomal fissure (fissure of von Ebner)

Question 14

The intrasclerotomal fissure gives rise to what developmental feature?

Answer 14

the perichordal disc

Question 15

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

Answer 15

the vertebral blastema

Question 16

What vessel will be identified adjacent to the vertebral blastema?

Answer 16

the segmental artery

Question 17

When will cartilage first form in the membranous vertebral blastema?

Answer 17

beginning in the 6th embryonic week

Question 18

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

Answer 18

chondrification

Question 19

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

Answer 19

centrum center, neural arch center, transverse process center

Question 20

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

Answer 20

six - 2 for the centrum, 2 for the neural arches, and 2 for each transverse process

Question 21

What is the earliest time that centers of ossification appear in the cartilaginous vertebra?

Answer 21

during the 7th embryonic week

Question 22

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

Answer 22

3 primary centers: 5 secondary centers

Question 23

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

Answer 23

centrum centers and neural arch centers

Question 24

What are the names/locations of the five secondary centers of ossification for a typical vertebra

Answer 24

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

Question 25

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

Answer 25

during puberty, typically ages 11-16 years old