Embryology Development Of Vertebral Columns Flashcards
How many pairs of somites are in an embryo ?
42
Where do the somites develop from ?
Paraaxial mesoderm
Where does the para axial mesoderm develop from
Intraembryonic Mesoderm
What part of the somite does the vertebral column develop from ?
Sclerotome
During which week do the Sclerotome cells migrate to form the future vertebrae?
4th week
Where do Sclerotome cells migrate to ?
Around the neural tube/spinal cord and the notochord to merge with the opposing somite
Loosely arranged cells are found in which segment ?
Cranial segment
Condensed tissue is found in which segment ?
Caudal segment
——————-It occurs when the caudal half of the sclerotome above grows
down & fuses with the cephalic half of the sclerotome below.
Resegmentation
Which structure bridges the
intervertebral discs?
Myotomes
Which structure is trapped between 2 Sclerotomes due to resegmenation?
Intersegmental Arteries
What forms the intervertebral discs ?
Mesenchymal cells between the caudal & cephalic parts of the original
sclerotome segment do not proliferate but fill the space between two
precartilaginous vertebral bodies and form the Intervertebral disc.
What is found between the pre cartilaginous vertebrae?
Mesenchymal cells/ annulus fibrosis and nucleus pulposus
What is the nucleus pulposus ?
Remnants of the notochord
What is annulus fibrosis develop from
Mesenchyme cells from between the caudal & cephalic parts of the original
sclerotome segment
Which week does the cartilaginous stage of development occur ?
6th - 8th
chondrification centers appear in each
mesenchymal vertebra when ?
6th week
Primary ossification centers appear during the?
8th week IUL
When do secondary ossification centres appear ?
After puberty (5 of them )
Total duration of ossification ?
Embryonic period (8th week) until 25 years of age
Primary curvatures:
Thoracic and sacral
Secondary curvatures :
Cervical (holding head up)
Lumbar (walking)
Gene responsible
for the proper orientation of the vertebrae in the
cranio-caudal direction?
HOX
What is the gene found to play an essential role in anterior-posterior development,
the ventral neural tube and somite patterning.
SHH
two successive vertebrae fuse asymmetrically or have half a vertebra missing.
Scoliosis
Syndrome with reduced mobility
and a short neck due to fused cervical vertebrae
Klippel–Feil Syndrome
imperfect fusion
or complete Non-fusion of the two halves of vertebral arches.
Spina Bifida/Cleft Vertebra
vertebrae slip
forward about the vertebral column
Congenital spondylolisthesis
