Anatomy Development of Musculoskeletal System

Question 1

Describe how scleretomes migrate to create a vertebrae.

Answer 1

From their initial location within the somite, the sclerotome cells migrate medially and ventrally towards the notochord. These cells meet the sclerotome cells from the other side to form the vertebral body. From this vertebral body, sclerotome cells move dorsally and surround the developing spinal cord, forming the vertebral arch. Other cells move distally to the costal processes of thoracic vertebrae to form the ribs.

Question 2

What happens if you have a problem in scleretome migration?

Answer 2

spina bifida

Question 3

What kind of spina bifida do you get if you have an open neural tube, this is fatal and often associated with anencephaly?

Answer 3

you get rachischisis

Question 4

What kind of spina bifida do you get if you have a malformation of the spine with a layer of skin covering over it?

Answer 4

spina bifida occulta

Question 5

What kind of spina bifida do you get if you have spinal fluid and meninges protruding through an abnormal vertebral opening; the malformation contains no neural elements and may or may not be covered by a layer of skin.

Answer 5

meningocele

Question 6

What form of spina bifida occurs when the spinal cord/neural elements are exposed through the opening in the spine, resulting in partial or complete paralysis of the parts of the body below the spinal opening. The impairment may be so severe that the affected individual is unable to walk and may have bladder and bowel dysfunction.

Answer 6

Myelomeningocele

Question 7

How do you get vertebral column formation?

Answer 7

2 adjacent sclerotomic segments fuse by proliferation of caudal half of one segment and proliferation of rostral half of the adjacent one, this gives rise to transverse process. (suscpetible for defects causing scoliosis)

Question 8

Why can you get scoliosis?

Answer 8

incomplete formation of lateral part of the vertebral processes

Question 9

The limbs develop through a series of (blank) with placement along the long axis as the first step (HOX genes).

Answer 9

inductive interactions

Question 10

The formation of limb buds in the (blank) is induced by adjacent somites.

Answer 10

lateral plate somatic mesoderm

Question 11

When do you get upper limb development?

lower limb?

Answer 11

24 days

28 days

Question 12

What is the directional progression of development?

Answer 12

develops cranial to caudally and proximal to distally

Question 13

There is a molecular regulation of limb development that tells cells where to go to differentiate, what regulates this?

Answer 13

proteins (such as ZPA)

Question 14

Polydactyl, syndactylym and meromelia limb defects are relatively rare except in cases of (blank) defects. Give an example

Answer 14

teratogenic

thalidomide

Question 15

Limb development is most susceptible to teratogens during the (blank) weeks

Answer 15

4th-5th week

Question 16

If you see congenial defects in the limbs, what should you be concerned for?

Answer 16

CV, GU, or cranial facial defects

Question 17

A non-developmental defect often associated with the limbs are amputations caused by (blank). What causes this?

Answer 17

amniotic bands

possible adhesions or tears of the amnion gets wrapped around portions of the extremities

Question 18

What does polydactyly mean?
What does syndactyly mean?
What does adactyly mean?

Answer 18

too many fingers
fusion of fingers
absence of digits

Question 19

WHy can some babies have huge bellies due to congenital muscle disorders?

Answer 19

anterior abdominal wall doesnt completely form the muscles which results in a belly without any muscular structures which results in prune belly syndrome
(ie dont have any rectus abdominus muscles)

Question 20

When do muscle masses appear?

Answer 20

5th week

Question 21

What kind of mesoderm initiates limb bud differentiation? Then what happens?

Answer 21

lateral plate mesoderm
Apical ectodermal ridge development-> causes mesenchymal proliferation-> ZPA organizes cells (cranially to caudally)-> get dorsal ventral organization (important for nerves and muscles)-> homebox genes determine shape and size of bones