Embryology Flashcards
Nerulation
folding of the ectoderm stimulated by the notochord
- neural groove
- neural crest
Neural groove
forms the entire CNS
Neural Crest
migrates into mesoderm to form PNS (*DRG), craniofacial structures, and cardiac tissues
Ventricular zone
tick pseudostratified epithelia (neuroepithelia–>neurons and glia)
in adults it is a think layer of ependymal cells
marginal zone
outer, most dorsal layer that becomes white matter
mantle zone
superficial to epithelia
- alar: sensory neuron: dorsal horn
- basal:motor neurons:ventral horns
Level of spinal cord during development
3 mo gestation: full length spinal cords
Birth: LV4/LV5
Adult: LV1/LV2
Spina Bifida
Family of neural tube defect disorders
occur most in the lumbosacral regions
Spina Bifida Occulta
vertebral arches fail to fuse, does not involve meninges, asymptomatic, marked by patch of hair or fat
Spina bifida cystics with menigocele
vertebral arches fail to fuse, meninges bulge out
Spina bifida cystics with meningomyelocele
vertebral arches fail to fuse and the meninges and spinal cord bulge out
Spina bifida with myeloschisis
most sever, neural plate fails to elevate and fold
- spinal cord remains open
- paralysis below this point
- associated with severe neurological defects
Resegmentation
week 4
Scleroterme fromthe somites divide into cranial and caudal halves which the fuse to the ones above and below themeselves
–> allows for myotomes to be connected to more than one vertebra which allows for movement `
Rib origins
Develop from costal (TPs) processes of the TVs
Sternum origins
arises from mesoderm, ossify cranial to caudal
meets up with ribs
Pectus excavatum
ribs grow in excess and push in on the sternum
sunken in chest wall
Pectus cerinactum
ribs push out on the sternum: pushed out chest wall
congential scoliosis
asymmetric fusion of the vertebra
formation of hemivertebrae
Klippel feil syndrome
fused CVs as a result of decreased resegmentation during development
results in a short neck, with decreased ROM
Poland syndrome
underdeveloped or absent pectoralis muscles
usually unilateral (R)
associated with syndactyly
may be due to lack of blood supply to chest during development
Amelia
No limb formation due to lack of AER formation or signaling
Meromelia
partial limb formation
Phocomelia
flipper-like limb formation (thalidomide)
Brachydactyly
shortness of digits
syndactylyl
fusion of 2+ digits
most common
lack of apoptosis of mesenchyme b/w/ digits
polydactyly
extra fingers or toes due to exs apoptotic zones
extrodactyly
absence of digits due to missing apoptotic zones
amniotic bands
break of amniotic sac an act as a tourniquet on limb buds or fingers
congential hip dislocation
underdeveloped acetabulum and head of femur–>lax joint capsule
dislocates before birth common with breech deliveries
tx: brace that laterally rotates the lower limb or pediatric hip replacement
