Deep back development

Question 1

What germ layer gives rise to muscles?

Answer 1

mesoderm

Question 2

What are myoblasts?

Answer 2

embryonic muscle cells

Question 3

What are myoblasts derived from?

Answer 3

mesenchyme in myotome regions of somites

Question 4

Myotomes can divide into which two divisions?

Answer 4

epaxial

hypaxial

Question 5

What does epaxial refer to?

Answer 5

dorsal

Question 6

What does hypaxial refer to?

Answer 6

ventral

Question 7

What nerves supply epaxial division muscles?

Answer 7

dorsal primary rami of spinal nerves

Question 8

What nerves supply hypaxial division muscles?

Answer 8

ventral primary rami of spinal nerves

Question 9

Which muscles are derived from epaxial division?

Answer 9

deep extensor muscles of the back

Question 10

Which muscles are derived from hypaxial division?

Answer 10

• infrahyoid
• flexor muscles of vertebral column
• quadratus lumborum

Question 11

Splenius muscle group arise from where?

Answer 11

posterior midline of the back and proceed laterally and superiorly to their insertion

Question 12

Erector spinae muscle group arise from where?

Answer 12

posterior midline of the back, or more laterally and run up longitudinally

Question 13

Transversospinalis muscle group arise from where?

Answer 13

laterally but travel toward the midline to their insertion

Question 14

During development, muscles of the deep back originally have what kind of arrangement?

Answer 14

segmental and only extend from one vertebra (segment) to the next

Question 15

How are larger muscle masses form during development?

Answer 15

fusion between adjacent segments, covering more than one segment
- sequential splitting of muscles occur later to form different superimposed layers