Trunk Anatomy

Question 1

What does the skeletal system develop from (both bone and cartilage)?

Answer 1

1. Mesenchymal cells (mesoderm)

2. Neural crest cells

Question 2

What process accompanies formation of the notochord and neural tube that is related to formation of part of the skeletal system?

Answer 2

Differentiation of the Intra-embryonic mesoderm lateral to the notochord and neural tube

Question 3

What structures does the intra-embryonic mesoderm lateral to the notochord and neural differentiate into?

Answer 3

1. Paraxial mesoderm
2. Intermediate mesoderm
3. Lateral Plate mesoderm

Question 4

What structures does the paraxial mesoderm form at the end of the 3rd week?

Answer 4

The paraxial mesoderm becomes segmented into blocks of mesoderm called somites (40-45 pairs0 at the end of the 3rd week

Question 5

What structures does each somite form?

Answer 5

1. Ventro-medial part - sclerotome (forms the vertebrae and ribs)
2. Dorso-lateral part - dermomyotome (cless from the myotome form striate muscle cells, cells from dermatome region form dermis)

Question 6

What cells do the cells of the sclerotome differentiate into?

Answer 6

Mesenchymal cells

Question 7

What do mesenchymal cells of the sclerotome have the potential to differentiate into?

Answer 7

1. Connective tissue cells

2. Precursors for ; i) blood cells ii) bone cells iii)cartilage cells iv)muscle cells and v) endothelium

Question 8

What is he function of the Homeobox (Hox) gene?

Answer 8

Regulates the migration and subsequent differentiation of the mesenchymal cells.

Question 9

What is the general process of development of the vertebrae?

Answer 9

The mesenchymal cells of the sclerotome migrate to the notochord, neural tube and body wall to condense and take part in formation of the vertebral column.

Question 10

What does the mesenchymal cells of the sclerotome that condense around the notochord form?

Answer 10

The mesenchymal cells that condense around the notochord forms the centrum (which gives rise to the body of the vertebral column)

Question 11

What does the mesenchymal cells of the sclerotome that condense around the neural tube form ?

Answer 11

The mesenchymal cells that condense around the neural tube form the right and left neural or vertebral arches which give rise to; the lamina, pedicle, spine, articular process and transverse process.

Question 12

What does the mesenchymal cells of the sclerotome that condense in the body wall form?

Answer 12

The mesenchymal cells that condense in the body wall form the costal process i.e. the costal element of the transverse process which gives rise to the ribs in the thoracic region.