Skeletal Flashcards
(33 cards)
What is the origin of the skeletal system?
Mesodermal origin from mesenchyme
What are the main cell types that mesenchyme differentiates into during skeletal development?
- Chondroblasts
- Osteoblasts
- Fibroblasts
What is mesenchymal condensation?
A process where mesenchymal cells become closely packed at a site where cartilage is to be formed
What is the role of chondroblasts in cartilage development?
They convert mesenchymal cells into cartilage-forming cells and lay down intercellular substance
What is the perichondrium?
A fibrous membrane formed by mesenchymal cells surrounding the developing cartilage
What are the two types of ossification in bone development?
- Membranous Ossification
- Endochondral Ossification
How do membranous ossification and endochondral ossification differ?
Membranous ossification directly converts mesenchymal tissues into bone, while endochondral ossification first forms a cartilaginous model of the bone
What are the subdivisions of intraembryonic mesoderm?
- Paraxial mesoderm
- Intermediate mesoderm
- Lateral plate mesoderm
What do somites differentiate into?
- Dermatome
- Myotome
- Sclerotome
What is the neurocranium?
The part of the skull that forms a protective case around the brain
What is the viscerocranium?
The part of the skull that forms the skeleton of the face
What are the two components of the neurocranium?
- Membranous Neurocranium
- Cartilaginous Neurocranium (Chondrocranium)
What are sutures in the context of the skull?
Narrow seams of connective tissue that separate flat bones of the skull
What are fontanelles?
Wide sutures where more than two bones meet in the skull
What is cranioschisis?
Failure of the cranial vault to form, leading to anencephaly
What causes craniosynostosis?
Premature closure of one or more sutures in the skull
What is scaphocephaly?
A condition where the skull becomes long and narrow due to early closure of the sagittal suture
What is brachycephaly?
A short skull resulting from premature closure of the coronal sutures
What is plagiocephaly?
Asymmetric flattening of the skull caused by premature closure of the coronal sutures on one side
How is a definitive vertebra formed?
By condensation of the caudal half of one sclerotome and fusion with the cranial half of the subjacent sclerotome
What does a typical vertebra consist of?
- Vertebral arch
- Vertebral foramen
- Body
- Transverse processes
- Spinous process
What do ribs develop from?
Sclerotome cells that remain in the paraxial mesoderm and grow out from the costal processes of thoracic vertebrae
How does the sternum develop?
Independently in the parietal layer of lateral plate mesoderm in the ventral body wall
What are limb buds?
Paddle-shaped outgrowths from the side wall of the embryo that develop into limbs
