GET THESE RIGHT OR ELSE
___ are narrow seams of connective tissue between bones, derived from neural crest and somitomeres
sutures
What cells and germ layer forms the face?
neural crest cells from the ectoderm
What is brachycephaly?
bicoronal suture premature closure, causing a short skull
Collectively somite cells constitute sclerotome that form
vertebrae and ribs
What gene mutation is an extra rib a result of?
Hox gene mutation
Where are fontanelles?
points where bones meet, sutures may be wide
What cell and germ layer forms the back of head/axial skeleton?
somitomeres/somites from paraxial mesoderm
What genes shape pattern of different vertebrae?
HOX GENES
IF YOU GET THIS WRONG DO A PUSHUP RIGHT NOW. CARSEN IF YOU GET IT WRONG DO 5 PUSHUPS
What genes are secreted by the neural tube floor and notochord
Shh and noggin
What molecule initiates expression of Shh in the anteroposterior axis?
retinoid acid
What allow the bones of the skull to overlap during birth
sutures and fontanelles
What germ layer and cells form the neurocranium?
paraxial mesoderm; occipital somites and somitomeres, neural crest
What gene allows for anteroposterior identity, craniocaudal segmentation, and spatiotemporal expression
HOX GENES
What genes cause PAX1 expression
Shh and noggin
What is partial or complete absence of one or more extremities called?
partial is meromelia and Amelia is complete absence
When does the anterior and posterior fontanelles close
posterior closes 3 months after birth, anterior closes in the middle of second year
What pharyngeal arch forms the malleus and incus?
Pharyngeal arch 1
Does the myotome re-segment?
NO IT DOES NOT
What is the nucleus pulpous and annulus fibrosus derived from
notochord; sclerotome
When long bones are absent and rudimentary hands and feet are attached to the trunk by small bones what is this called?
phocomelia, a form of meromelia
Name the disorder: most causes are genetic, premature closure of the saggital suture. causes frontal-occipital expansion making the skull long and narrow
scaphocephaly, a type of craniosynostosis
Explain the difference between intramembranous ossification and endochondral ossification
intra: mesenchyme differentiates directly into bone
end: bone is pre-formed in cartilage
Name the 3 types of spina bifida and their differences
occulta: imperfect fusion or nonunion of vertebral arches, skin intact, may have hair tuft in sacral region
meningocele: meninges protrude
myelomeningocele: meninges and part of spinal cord protrude
What is klippel-feil syndrome
when somites do not segment properly leading to fusion of two or more cervical vertebrae
What is the difference between brachydactyly, syndactyly, polydactyly, and cleft hand?
brachy: short digits
synd: apoptosis fails and fusion of 2 or more digits
poly: extra fingers or toes
cleft: cleft between metacarpal bones