Day 7

Question 0

what is the maximum number of somites observed during development?

Answer 0

38 pairs

Question 1

What embryonic structure gives rise to the somites?

Answer 1

paraxial mesoderm

Question 2

How many somites will be formed during deveopment

Answer 2

42-44 pairs of somites

Question 3

Name the areas of cellular differentiation formed with the somite.

Answer 3

sclerotome, myotome and dermatome

Question 4

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

Answer 4

membranous, cartilaginous, skeletal or osseous

Question 5

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

Answer 5

the perichordal blastema

Question 6

The perichordal blastema gives to what processes?

Answer 6

neural processes and costal processes

Question 7

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

Answer 7

intersegmental artery

Question 8

What forms between the sclerotomites of a perichordal blastema?

Answer 8

the intresclerotomal fissure (fissure of von Ebner)

Question 9

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

Answer 9

the vertebral blastema

Question 10

What vessel will be identified adjacent to the vertebral blastema?

Answer 10

the segmental artery

Question 11

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

Answer 11

chondrification

Question 12

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

Answer 12

six…2 for the centrum, 2 for the neural arches, 2 for the transverse process

Question 13

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

Answer 13

during the 7th embryonic week

Question 14

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

Answer 14

3 primary centers: 5 secondary centers

Question 15

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

Answer 15

centrum centers and neural arch centers

Question 16

What is the time and location for the earliest center of ossification in the typical vertebra?

Answer 16

centrum centers in the lower thoracics and upper lumbars during the 9-10 fetal week

Question 17

When and where will neural arch centers of ossification first appear?

Answer 17

lower cervicals and upper thoracics in the 9-10 fetal week

Question 18

What is the name given to the cartilage joint formed between the centrum and neural arch?

Answer 18

neurocentral synchondrosis

Question 19

What is the direction for closure of the neurocentral synchondrosis along the spine?

Answer 19

cranial to caudal

Question 20

Which location of the spine will first exhibit obliteration of the neurocentral synchondrosis?

Answer 20

cervicals

Question 21

What is the name given to the cartilage joint formed between neural arch centers of ossification?

Answer 21

neural arch synchondrosis

Question 22

What is the direction for closure of the neural arch synchondrosis along the spine?

Answer 22

caudal to cranial

Question 23

What location of the spine will first exhibit obliteration of the neural arch synchondrosis?

Answer 23

lumbars

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

Question 26

What are the ages of appearance and the events occurring at each step in the formation of bone at the superior and inferior surface of the vertebral body?

Answer 26

ages 7-9 years, appearance of epiphyseal plate centers of ossification
age 12 years, formation of the epiphyseal ring
age 15 years, formation of the epiphyseal rim