Lower Limb Development Flashcards
When is the trilaminar disc stage?
17 days
Which core tissue are the limb buds derived from?
Lateral plate mesoderm (covered by ectoderm)
What are the limb buds?
Outpouchings from ventrolateral body wall
What does the mesoderm core differentiate into and what does this form?
Mesoderm to mesenchyme to bones and connective tissue of limbs
Where is the paraxial mesoderm situated in the trilaminar disc stage?
Lateral to notochordal process, medial to intermediate mesoderm and even more medial to paraxial mesoderm.
What does the paraxial mesoderm form?
Somites either side of neural tube
What two parts do somites differentiate into?
Sclerotome ventrally and dermomyotome dorsolaterally
What does sclerotome form?
Vertebral column
What does dermatome and myotome form?
Dermatome forms dermis of skin, myotome gives rise to skeletal muscles.
What 2 components does the myotome differentiate into?
Dorsal epimere and ventral hypomere
What does dorsal epimere differentiate into?
Back muscles innervated by dorsal rami of spinal nerves
What does ventral hypomere differentiate into?
Muscles of thoracic and abdominal walls and muscles of limbs which are innervated by ventral rami of spinal nerves
What vertebral levels does the limb skeletal muscle from the adjacent hypomere arise from?
Upper limb buds - C5-8. Lower limb buds - L3-5.
Which muscles do the two condensations of the limb buds divide into?
Anterior condensation = flexors of upper and lower.
posterior condensation = extensors of upper and lower.
Which branches of the ventral primary rami of spinal nerves supply upper limb buds?
Brachial plexus = C5-T1
