Classification of bones according to origin Flashcards
1
Q
How are bones classified according to the origin ?
A
- Membranous bones : These bones develop in the embryonic life in a membrane of connective tissue ( intra-membranous or mesenchymal ossification ) like bones of the vault of the skull , facial bones and shaft of the clavicle.
- Cartilaginous bones : These bones develop from a cartilage model ( intracartilagenous or chondral ossification ) like long bones of limbs , vertebral column and thoracic cage.
2
Q
The clavicle bone doesn’t follow all the criteria of a long bone. Explain.
A
The clavicle is ossified from a long bone , it has no medullary cavity.
3
Q
What is the first bone to begin ossification ?
A
The clavicle ( 5th - 6th week of IUL )
4
Q
How does the chondral ossification happen ?
A
- At the 8th week of intra-uterine life , a center of bone formation appears in the middle of the cartilage model and is called primary center of ossification. The part of the bone ossified from this part is diaphysis.
- After birth , other centers of ossification appear knows as secondary center of ossification in the ends of the long bones. The parts which are ossified from the secondary center of ossification are called epiphysis.
- The age of fusion between the diaphysis and epiphysis varies between 15 to 22 years ( in females earlier by 1 to 2 years than males ).
5
Q
What is periostium and what is its function ?
A
It consists of an outer fibrous layer and an inner cellular layer ( osteogenic ) , it gives attachment to the muscles , help in bone growth in width , healing of fractures and transmit blood vessles.
6
Q
What are the main blood supply of the bone ?
A
- Nutrient artery : passes through the nutrient foramen in the diaphysis to reach the medullary cavity.
- Metaphyseal epiphyseal arteries : They anastomose with nutrient branch.
- Periosteal arteries : are found beneath the muscular and ligamentous attachments to the bones.
