Embryology of the Vertebral Column Flashcards
When does the embryonic disc form?
second week in utero
When does gastrulation occur or a 3-layered embryo form?
third week in utero
What are the 3 layers of the embryo called?
ectoderm, mesoderm, and endoderm
Invagination of ectoderm along the primitive streak gives rise to what embryonic structure?
notochord
What is the name given to the mesoderm that will give rise to the vertebral column?
paraxial mesoderm
What embryonic structure gives rise to the somites?
paraxial mesoderm
Somites are separated from one another by what embryonic feature?
intersegmental fissures
Name the areas of cellular differentiation formed within the somite.
sclerotome, myotome, and dermatome
What are the names of successive vertebral columns formed during development?
membranous, cartilaginous, skeletal or osseous
Migration of a somite pair to surround the notochord forms what developmental feature?
the perichordal blastema
The perichordal blastema gives rise to what processes?
neural processes and costal processes
What is the name of the artery located between adjacent perichordal blastemae?
intersegmental artery
What forms between the sclerotomites of a perichordal blastema?
the intrasclerotomal fissure (fissure of von Ebner)
The intrasclerotomal fissure gives rise to what developmental feature?
the perichordal disc
The union of a dense caudal sclerotomite and a loose cranial sclerotomite from adjacent perichordal blastemae give rise to what feature?
the vertebral blastema
What vessel will be identified adjacent to the vertebral blastema?
the segmental artery
When will cartilage first form in the membranous vertebral blastema?
beginning in the 6th embryonic week
What is the name given to the replacement of mesoderm by cartilage?
chondrification
What are the names given to the centers of chondrification within the vertebral blastema?
centrum center, neural arch center, transverse process center
How many centers of chondrification typically appear in the vertebral blastema?
six - 2 for the centrum, 2 for the neural arches, and 2 for each transverse process
What is the earliest time that centers of ossification appear in the cartilaginous vertebra?
during the 7th embryonic week
What is the ratio of primary to secondary centers of ossification for a typical vertebra?
3 primary centers: 5 secondary centers
What are the names of the primary centers of ossification for a typical vertebra?
centrum centers and neural arch centers
What are the names/locations of the five secondary centers of ossification for a typical vertebra
tip of the transverse process, tip of the spinous process, epiphyseal plate centers
What is the range of appearance for secondary centers of ossification of a typical vertebra?
during puberty, typically ages 11-16 years old
