Musculoskeletal Development

Question 1

Endochondral ossification

Answer 1

A cartilage model forms first and is eventually replaced by bone
Axial skeleton, cranial base, appendicular skeleton (except clavicles)

Question 2

Intramembranous ossification

Answer 2

Bone forms directly from mesenchymal cells without prior formation of cartilage
Underlies formation of the cranial vault and most of the bones of the face

Question 3

3 types of cells in endochondral bone development and their functions

Answer 3

1. Chondrocytes: secrete cartilage
2. Osteoblasts: secrete bone matrix
3. Osteoclasts: bone resportion
   Only 2 and 3 in intramembranous ossification

Question 4

3 types of muscle

Answer 4

Skeletal: voluntary, develops in association with bone
Smooth: develops in association with formation of the walls of the viscera, blood vessels, and glands
Cardiac: only in the heart

Question 5

Muscle cell precursors

Answer 5

Myoblasts

Undergo extensive proliferation to form terminally differentiated, postmitotic myocytes

Question 6

Satellite cells

Answer 6

Activate differentiation and repair the damage when the muscle is injured

Question 7

Sclerotome

Answer 7

Gives rise to the bones of the axial skeleton

Vertebrae proper

Question 8

Dermamyotome

Answer 8

Forms the dermis of the back skin of the trunk and neck

Also to all the musculature of the limbs and some of the tongue musculature

Question 9

Syndetome

Answer 9

Contains the progenitor of the tendons

Develops between the myotome and the sclerotome

Question 10

Lateral plate mesoderm

Answer 10

Forms the sternum and bones of the limbs and contributes to the dermis of the trunk

Question 11

Neural crest cells give rise to…

Answer 11

Bones of the face and neck

Dermis of the head

Question 12

Unsegmented paraxial mesoderm gives rise to…

Answer 12

Facial, masticatory and laryngeal muscles

Question 13

Bones of the cranial vault and cranial base are formed by which 3 things…

Answer 13

Segmented paraxial mesoderm
Unsegmented paraxial mesoderm
Neural crest

Question 14

3 skeletal systems in ENDOSKELETON

Answer 14

Axial (derived from somites)
Craniofacial (largely derived from the neural crest)
Appendicular (limb bud mesoderm)

Question 15

What makes up the EXOSKELETON

Answer 15

Tooth, collar bone, and in the cases of some reptiles horns, plates and armour/sheels
Teeth are the only part of our skeleton that sticks out of our tissues

Question 16

The dermamyotome gives rise to the X and each form the..

Answer 16

X: myotome
The dermamyotome forms the dermis
The myotome splits into the epimere (epaxial muscles) and hypomere (hypaxial muscles)

Question 17

Re-segmentation of the sclerotomes to form the vertebrae

Answer 17

Each sclerotome splits into cranial and caudal segments
As the segmental spinal nerves grow towards the cranial portion of the somite to innervate the myotomes, the cranial segment of each sclerotome recombines with the caudal segment of the next cranial to form a vertebral rudiment

Question 18

What structure of the spinal cord does the notocord form?

Answer 18

The nucleus pulposus of the disc

The core of the intervertebral discs

Question 19

Epimere

Answer 19

Forms the deep muscles of the back

Question 20

Hypomere

Answer 20

Forms the 3 layers of the anterolateral muscles in the thorax (external and internal oblique, transversus abdominis)
In the ab region, forms the rectus abdominis

Question 21

Name of the gene that regulates the proliferation and differentiation of the dermatomyotome

Answer 21

Wnt11

Question 22

What week do you have generation of the musculoskeletal system beginning?

Answer 22

4th week

Question 23

Apical ectodermal ridge

Answer 23

Along the distal margin of the limb bud

Maintains the outgrowth of the limb bud along the proximal-distal axis

Question 24

1. Stylopod
2. Zeugopod
3. Autopod

Answer 24

1. Upper arm
2. Forearm
3. Digits

Question 25

Retinoic acid

Answer 25

Vitamin A derivative
Signals from the mesenchyme to influence the AER to keep the underlying mesenchyme proliferating
So that you can form limbs

Question 26

Hox genes

Answer 26

Homeobox genes
Transcription factors
Progressive expression of them over time and space pattern the proximal and distal elements of the autopod

Question 27

Zone of Polarizing Activity

Answer 27

Patterns the digits
Allows there to be polarization in the hands for example
Duplicate this and you get a mirror image duplication of the limb

Question 28

Sonic Hedgehog (Shh)

Answer 28

Zone of polarizing activity patterning molecule
Secreted protein that is crucial for development for a lot of parts of our bodies
Important for embryonic pattern of development

Question 29

Bone formation from the NCC vs the somites

Answer 29

Somites: endochondral formation
NCC: intramembranous formation