Musculoskeletal Development Flashcards
Endochondral ossification
A cartilage model forms first and is eventually replaced by bone
Axial skeleton, cranial base, appendicular skeleton (except clavicles)
Intramembranous ossification
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
3 types of cells in endochondral bone development and their functions
- Chondrocytes: secrete cartilage
- Osteoblasts: secrete bone matrix
- Osteoclasts: bone resportion
Only 2 and 3 in intramembranous ossification
3 types of muscle
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
Muscle cell precursors
Myoblasts
Undergo extensive proliferation to form terminally differentiated, postmitotic myocytes
Satellite cells
Activate differentiation and repair the damage when the muscle is injured
Sclerotome
Gives rise to the bones of the axial skeleton
Vertebrae proper
Dermamyotome
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
Syndetome
Contains the progenitor of the tendons
Develops between the myotome and the sclerotome
Lateral plate mesoderm
Forms the sternum and bones of the limbs and contributes to the dermis of the trunk
Neural crest cells give rise to…
Bones of the face and neck
Dermis of the head
Unsegmented paraxial mesoderm gives rise to…
Facial, masticatory and laryngeal muscles
Bones of the cranial vault and cranial base are formed by which 3 things…
Segmented paraxial mesoderm
Unsegmented paraxial mesoderm
Neural crest
3 skeletal systems in ENDOSKELETON
Axial (derived from somites)
Craniofacial (largely derived from the neural crest)
Appendicular (limb bud mesoderm)
What makes up the EXOSKELETON
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
The dermamyotome gives rise to the X and each form the..
X: myotome
The dermamyotome forms the dermis
The myotome splits into the epimere (epaxial muscles) and hypomere (hypaxial muscles)
Re-segmentation of the sclerotomes to form the vertebrae
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
What structure of the spinal cord does the notocord form?
The nucleus pulposus of the disc
The core of the intervertebral discs
Epimere
Forms the deep muscles of the back
Hypomere
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
Name of the gene that regulates the proliferation and differentiation of the dermatomyotome
Wnt11
What week do you have generation of the musculoskeletal system beginning?
4th week
Apical ectodermal ridge
Along the distal margin of the limb bud
Maintains the outgrowth of the limb bud along the proximal-distal axis
- Stylopod
- Zeugopod
- Autopod
- Upper arm
- Forearm
- Digits
Retinoic acid
Vitamin A derivative
Signals from the mesenchyme to influence the AER to keep the underlying mesenchyme proliferating
So that you can form limbs
Hox genes
Homeobox genes
Transcription factors
Progressive expression of them over time and space pattern the proximal and distal elements of the autopod
Zone of Polarizing Activity
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
Sonic Hedgehog (Shh)
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
Bone formation from the NCC vs the somites
Somites: endochondral formation
NCC: intramembranous formation
