Day 7 Flashcards
what is the maximum number of somites observed during development?
38 pairs
What embryonic structure gives rise to the somites?
paraxial mesoderm
How many somites will be formed during deveopment
42-44 pairs of somites
Name the areas of cellular differentiation formed with the somite.
sclerotome, myotome and dermatome
What are the names of the 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 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 intresclerotomal fissure (fissure of von Ebner)
The union of a dense caudal sclerotomite and a loose cranial sclerotomite from adjacent perichordal blastemae gives rise to what feature?
the vertebral blastema
What vessel will be identified adjacent to the vertebral blastema?
the segmental artery
What is the name given to the replacement of mesoderm by cartilage?
chondrification
How may centers of chondrification typically appear in the vertebral blastema?
six…2 for the centrum, 2 for the neural arches, 2 for the transverse process
What is the earliest time that the centers of ossification appear in the cartilaginous vertebra?
during the 7th embryonic week
What is the ration 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 is the time and location for the earliest center of ossification in the typical vertebra?
centrum centers in the lower thoracics and upper lumbars during the 9-10 fetal week
When and where will neural arch centers of ossification first appear?
lower cervicals and upper thoracics in the 9-10 fetal week
What is the name given to the cartilage joint formed between the centrum and neural arch?
neurocentral synchondrosis
What is the direction for closure of the neurocentral synchondrosis along the spine?
cranial to caudal
Which location of the spine will first exhibit obliteration of the neurocentral synchondrosis?
cervicals
What is the name given to the cartilage joint formed between neural arch centers of ossification?
neural arch synchondrosis
What is the direction for closure of the neural arch synchondrosis along the spine?
caudal to cranial
What location of the spine will first exhibit obliteration of the neural arch synchondrosis?
lumbars
