limb development Flashcards
when does limb development begin?
mid to late embryonic phase - 4-8 weeks
what week are limb buds visible?
end of week 4 - limb buds are visible as outpouchings from the ventrolateral body wall
what forms the bones and connective tissue of limbs?
mesenchyme
where is the skeletal muscle derived from?
paraxial mesoderm
what are somites?
the paraxial mesoderm forms a series of blocks called somites on each side of the neural tube - these differentiate into numerous structures including the muscles of the limbs
what does the sclerotome form?
the vertebral column
what does the dorsolateral part of the somites form?
the dermomyotome
what does the epimere form?
back muscles which are innervated by the dorsal rami of spinal nerves
what does the hypomere form?
he muscles of thoracic and abdominal walls and muscles of limbs, they are innervated by the ventral rami of spinal nerves
where does the developing upper limb skeletal muscles arise?
the hypomere region adjacent to C5-C8
where does the developing lower limb skeletal muscles arise
the hypomere region adjacent to L3-L5
how are limb buds innervated?
by branches of the ventral primary rami of spinal nerves
when does limb rotation occur?
between 6 and 8 weeks
how do the upper limbs rotate?
upper limbs rotate 90 degrees laterally
how do the lower limbs rotate?
lower limbs rotate 90 degree medially
