Musculoskeletal Development I

Question 1

Skeletal tissue is ______ in origin

Answer 1

Mesenchymal

Question 2

What structures do the Mesodermal scletotomes (of somites) give rise to?

Answer 2

Vertebral column
Ribs
Sternum

Question 3

What structures do the Lateral plate mesoderm give rise to?

Answer 3

Limb bones

Girdles

Question 4

What structures do the head of the mesoderm give rise to?

Answer 4

Calvaria and base of the skull

Question 5

During the Bone/Cartilage differentiation pathway, what promotes mesenchymal cells to undergo condensation (grouping together/clumping)?

Answer 5

N-Cadherins

Question 6

During the Bone/Cartilage differentiation pathway, ______ stimulates the synthesis of fibronectin and N-CAM

Answer 6

TGF-Beta

Question 7

During the Bone/Cartilage differentiation pathway, the membranous pathway requires what transcription factors?

If they go through this pathway, what do mesenchymal cell become?

Answer 7

Runx-2
Osx

Osteoblasts

Question 8

During the Bone/Cartilage differentiation pathway, for the permanent cartilage pathway what does mesenchymal condensation form?

Answer 8

Chondroblasts

Question 9

During the Bone/Cartilage differentiation pathway, for th epermanent cartilage pathway what are the affects of Sox9?

Answer 9

Causes chondroblasts to secrete collagen II and cartilage matrix

Is continuously expressed in permanent cartilage

Question 10

During the Bone/Cartilage differentiation pathway, for the endochondral bone pathway what 3 factors induce the cartilage to undergo hypertrophy?

Answer 10

Runx-2
Indian Hedgehog (Ihh)
BMP-6

Question 11

During the Bone/Cartilage differentiation pathway, for the endochondral bone pathway what do hypertrophic cartilage cells secrete?

Answer 11

VEGF- Vascular endothelial growth factor

Question 12

What are the effects of VEGF?

Answer 12

Invading blood vessels erode the hypertrophic acrtilage and bring osteoblasts to replace cartilage with bone

Question 13

What parts of the vertebra are the centrum derived from?

Answer 13

Ventral and medial parts of paired sclerotomes

Question 14

What parts of the vertebra are the neural arches derived from?

Answer 14

Dorsal regions of the sclerotome

Question 15

What does proximal development of costal processes/ribs depend on?

Answer 15

Myotomic myogenic factors Myf-5 and Myf-6

Question 16

What does distal development of costal processes/ribs depend on?

Answer 16

BMP signals from somatopleural mesoderm

Question 17

Describe the Atlas bone

Answer 17

It is the first cervical vertebral bone

Your world is in your head and this bone holds your head up, hence the greek mythological man Atlas holding up the world

Allows for the yes movement

Question 18

Describe the Axis bone

Answer 18

It is the second cervical vertebral bone

Allows for you to turn you head in the no direction

Question 19

Describe the development of the sternum in terms of where it is derived from

Answer 19

Derived from the lateral plate mesoderm

Question 20

Where do clavicles arise from?

Answer 20

Neural crest

Question 21

What pathway do clavicles develop from?

Answer 21

Intramembranous pathway

Question 22

What is the one of the first bones to become ossified?

Answer 22

Clavicles

Question 23

What are the 3 major components of the embryonic skull components?

Answer 23

• Neurocranium
• Viscerocranium
• Occipital Sclerotomes

Question 24

Describe the Neurocranium of the embryonic skull

Answer 24

Part of the skull that surrounds the brain

Question 25

What are the 2 portions of the Neurocranium

Answer 25

- Cartilaginous portion- Forms the base of the skull | - Membranous portion

Question 26

What does the cartilaginous Neurocranium give rise to?

Answer 26

-Occipital, phenoid, ethmoid, and parts of the temporal

Question 27

What does the membranous Neurocranium give rise to?

Answer 27

-Part of the occipital, parietals, frontals, and parts of the temporal

Question 28

What does the Viscerocranium surround?

Answer 28

- The oral cavity and pharynx | - Viscerocranium refers to the pharyngeal arches

Question 29

Elongation of primary ossification centers is due to _____

Answer 29

Shh

Question 30

What are Neurocranium bones characterized by?

Answer 30

A transient appearance of type II collagen and cartilage specific proteoglycan

Question 31

What causes the closure of sutures (portion between bones in the skull)

Answer 31

The inhibition of Noggin on BMP

Question 32

Differentiate the Hox gene boundaries for the different regions of the vertebral column.

Answer 32

Occipital-Cervical Boundary- Hox3 Cervical-thoracic Boundary- Hox6 Attached Floating Ribs- Hox9

Question 33

What is the relationship of Hox gene expression and the development of the vertebral column?

Answer 33

Amount of Hox Expression Occipital < Caudal < Sacral < Lumbar < Cervical < Thoracic

Question 34

How does retinoic acid affect the expression of the Hox genes and the development of the vertebral column?

Answer 34

Retinoic Acid regulates Hox gene expression by binding to its enhancer sequence to increase expression of Hox

Question 35

What are homeotic transformations?

Answer 35

The transformation of one organ into another, arising from a mutation in homeotic genes.

Question 36

What is the primordium for the atlas?

Answer 36

Cervical Somites 1 and 2 --> C1 Vertebra --> Atlas

Question 37

What is the primordium for the axis?

Answer 37

Cervical Somites 2 and 3 --> C2 Vertebra --> Axis

Question 38

What do pharyngeal arches compose?

Answer 38

They are the cartilaginous portions of the viscerocranium