week 12- MSK Flashcards
skeleton is composed of 2 tissues
- bone
- cartilage
skeleton is composed of 3 cell types
- osteoblasts
- osteoclasts
- chondrocytes
skeletal tissue derive from 3 embryonic cell lineages
- cranial neural crest
- paraxial mesoderm
- lateral plate mesoderm
CRANIOFACIAL SKELETON, CALVARIUM, MIDFACE, MANDIBLE AND TEETH DERIVE FROM
cranial neural crest cell
axial skeleton derived from
paraxial mesoderm
limbs derive from
lateral plate mesoderm
notochord and neural tube form in week
3
intraembryonic mesoderm lateral to the notochord and neural tube thicken to form 2 longitudinal columns of ____
paraxial mesoderm
appear as bead-like elevations along the dorsolateral surface of the embryo.
somites
somites differentiate into 2 parts:
- ventromedial part
2. dorsolateral part
ventromedial part is the ___ and ___
sclerotome vertebra and ribs
dermomyotome from the
- myoblasts (muscle cells)
- dermis (fibroblasts)
dorsolateral part
neural plate fuse to form the neural tube and is made from
ectoderm
limb buds start to develop in week 6, as clusters of ___ cells covered by ___
mesenchymal
ectoderm
Limbs develop in a ____ sequence
proximodistal
the __and ___ form first, followed by ___ and ___, ___ and ___, metacarpal and matatarsal, and finally phalanges
- humerus & femur
- radius & ulna
- tibial & fibula
osteogenesis begins in the __ and ___ by 8 weeks
clavicle & mandible
by __-__ weeks, the primary ossification centers of the long bones formed
11-12
___ are primary ossification centres
diaphysis
-shaft of long bones
___ are secondary ossification centres
epiphysis
-ends of long bones
epiphysis form __ or articulation with another bone
joints
most secondary ossification centres develop ___
after birth
prenatally, ___ epiphysis are visible at 32-35 weeks
distal femoral
prenatally, ___ epiphysis are visible by 34-35 weeks
proximal tibia (sometimes prox humerus)
Visualization of these epiphyses aids in the determination of fetal ___ maturity in late pregnancy
lung
limbs are fully developed and primary ossification centers image at __ weeks
10
metacarples and phalanges of hands imaged ___
second trimester
most severe skeletal anomalies picked up on US at
19-20 weeks
mild forms of anomalies expressed __ in pregnancy
later
most common measured long bone
femur (leg bone)
echogenicity of the femur
equally hyperechoic
__ has similar appearance to femur
humerus (arm where bicep is)
tibia is __ than ___ and oriented medially
thicker
fibula
fibula lies
laterally
distal radius and ulna should end at __ point
the same
ulna is __ than radius
longer
tibia is the __ bone
front/ medial of leg
fibula is the ___ bone
lateral of leg
normal appearance of fetal hand is __ hypoechoic carpal bones, 5 ___ metacarpal bones, 5 digits of ___ lengths
unossified
hyperechoic
varrying
hand should always be seen in __ and ___
flexion
extension
foot has 5 __ bones
tarsal
technical factors that inhibit sonogrpaher ability to visualize fetal limbs
- not enough amniotic fluid
- too much amniotic fluid
- limbs in NEAR field
Polyhydramnios
too much fluid in baby swimming pool
__ weeks LMP start to grow limbs, ___ weeks LMP can see hands / feet
6
8
