4.3 Muscle Embryology

Question 1

What are the 3 parts of the somite?

Answer 1

sclerotome, myotome, dermatome

Question 2

What does the sclerotome form?

Answer 2

migrates around neural tube to form cartilaginous precursor of vertebrae

Question 3

What does myotome form?

Answer 3

myoblasts differentiate into myotubes to form skeletal muscle

Question 4

What does dermatome form?

Answer 4

dermis

Question 5

limb buds come from elevations of ________ mesoderm

Answer 5

somatopleuric

Question 6

skeletal muscles and vasculature develop from ________

Answer 6

somites

Question 7

bones and tendons are derived from the _______ and have no somite contribution

Answer 7

lateral plate

Question 8

craniocaudal development regulatory factors?

Answer 8

Hox genes, ZPA

Question 9

ventral dorsal regulatory factors?

Answer 9

wnt-7a (dorsal) and engrailed-1 (ventral)

Question 10

proximodistal regulatory factors?

Answer 10

apical ectodermal ridge and progress zone (PZ)

Question 11

rotation of limb buds?

Answer 11

extend caudally –> ventral extension –> upper and lower rotation in opposite directions

Question 12

more common in boys, walking on ankles

Answer 12

clubfoot

Question 13

more common in girls, flat acetabulum

Answer 13

congenital hip dislocation

Question 14

type of spina bifida with hairs over missing vertebral spinous process

Answer 14

occulta

Question 15

type of spina bifida with meningomyelocele

Answer 15

cystica

Question 16

type of spina bifida with neural tissue that has not formed at all

Answer 16

rachischisis

Question 17

MYF5, back extensors innervated by dorsal rami

Answer 17

epimere

Question 18

Myo-D, back flexors, trunk and extremities innervated by ventral rami

Answer 18

hypomere

Question 19

in the vertebral column, ______ combine above and below to form each vertebra

Answer 19

somites

Question 20

layers of the skin:

• epidermis forms from ______
• dermis froms from _____ + ______
• melanocytes from ______

Answer 20

ectoderm, dermatome + somites, neural crest