Limb development

Question 1

What develops from somatic (lateral plate) mesoderm? Somitic (paraxial mesoderm)?

Answer 1

Bones, joints, CT; limb muscles

Question 2

Dorsal limb muscles are primarily___ and innervated by ___ division of ventral ramus while ventral are mostly___ and ____

Answer 2

extensor, posterior; flexor, anterior

Question 3

AER (apical ectodermal ridge)

Answer 3

determines proximo-distal polarity of limb via FGF. AER regresses (apoptosis) to form digits.

Question 4

ZPA (zone of proliferative activity)

Answer 4

determines pre/postaxial polarity via SHH. Located on postaxial side so high density SHH signal=postaxial structure differentiation

Question 5

what determines dorsal/ventral limb patterning

Answer 5

WNT/LMX1 gene (Dorsal) and ENG-d(ventral)

Question 6

VACTERL

Answer 6

vertebral defects, anal atresia, cardiac defects, tracheo-esophageal fistula, renal nomalies, limb abnormalities

Question 7

Normal bone/joint development

Answer 7

endochondral ossification, joints don’t chondrify or ossify they just remain dense CT

Question 8

All limb muscles develop from the ___ so are innervated by___ of spinal nerves

Answer 8

hypomere, ventral rami

Question 9

Organization of Brachial plexus

Answer 9

C5/C6>S trunk, C7>M trunk, C8/T1>I trunk; then they all split anterior and posterior. S/M>lateral cord, I>medial chord

Question 10

What are the anterior division nerves?

Answer 10

musculocutaneous, median, ulnar, obturator, tibial

Question 11

What are the posterior division nerves?

Answer 11

axillary, radial, gluteal, femoral, fibular