MSK embryology Flashcards
when does embryonic folding generally happen?
week 4 of development
how does embryonic folding occur?
occurs in 2 directions
-lateral folding is driven by somites
-cephalocaudal / head and tail folding which is driven by CNS, particularly brain
-folds happen simultaneously and close the body wall of the embryo and create a tube like structure
closes the body wall and creates a tube like centre
how are embryos staged?
the the number of smote pairs they have
what makes up the amnionic membrane?
continuous should join at the top. embryo membrane to extra embryonic membrane. encloses a space where amnionic fluid should be
what is the function of the amnionic space and fluid?
protection, remains until birth, this is the fluid that leaks when ‘water breaks’
what is in the centre of the neural tube?
neural canal
what is the mantle zone of the neural tube?
where it is more cellular, made up of neuroblasts, cells going under mitosis, future grey matter of CNS
what does the marginal zone form?
white matter of CNS
what are the 3 main parts of the mesoderm?
paraxial
lateral plate
intermediate
what is the notochord?
signalling centre during development of mesoderm and CNS, sends out signals to mesoderm to tell it to differentiate
transient structure
parts go on to form nucleus pulpous
what mesoderm is adjacent to neural tube?
paraxial mesoderm
how many blocks of paraxial mesoderm are there?
2, these go on to form somites
what kind of sequence do the somites form in?
cranial caudal sequence
what are the somites?
transient structures that appear and disappear, differentiate to give different structures in MSK
what are the zones of the somite?
dermomyotome
sclerotome
what is the dermomyotome?
outer part of somite
goes on to form dermis of skin and skeletal muscle
can have spaces
more cellular
what is the sclerotome?
ventral part of somite
more cellular that dermomyotome
where does somite come from?
paraxial mesoderm
what does the sclerotome go on to form?
vertebrae and ribs
what does interimediate mesoderm connect?
connects paraxial mesoderm to somatic and lateral plate mesoderm
what does intermediate mesoderm differentiate into?
uriogential structures
what is the big space in the middle of the embryo?
dorsal aorta, blood cells in the aorta
what is the lateral plate mesoderm
most lateral in the embryo
been pushed apart into 2
where is the somatic lateral plate mesoderm?
directly under the one or two laters thick of ectoderm
where is the sphlanic LPM?
continuity with endoderm
at the bottom of embryo on the outside