the process by which bone forms
ossification
ossification four principal situations
initial formation of bones
growth of bones
remodeling of bones
repair of fractures
bone development begins during ___ to ___ week
6th to 7th
two types of ossification
intramembranous and endochondral
bone formation within hyaline cartilage that develops from mesenchyme
endochondral ossification
primary ossification center of a long bone
diaphysis
secondary ossification occurs in the
epiphysis
bone formation directly within mesenchyme arranged in a sheetlike layers that resemble membranes
intramembranous
epiphyseal plate consist of four zones
RPHC
zone of:
resting cartilage
proliferating cartilage
hypertrophic cartilage
calcified cartilage
Because of the ce division in the ________________, the diaphysis of a bone _____ in ______.
epiphyseal growth plate
increases
length
Bone grows in __________ due ti addition if new bone tissue by _________ around the outer surface of the bone. This process is called _________.
thickness/diameter
periosteal osteoblasts
appositional growth
other term for ossification
osteogenesis
intra means
within membrane
“little fountains”
fontanels
chondro means
cartilage
mesenchyme is transformed into ________ which produce a hyaline cartilage matrix
chondroblasts
age of ____, bone loss exceeds bone gain
35
Endochondral Ossification of a Long bone
- A cartilage model, with the general shape of the mature bone, is produced by chondrocytes. A perichondrium surrounds most of the cartilage model.
- The chondrocytes enlarge, and cartilage is calcified. A bone collar is produced, and the perichondrium of the diaphysis becomes the periosteum.
- A primary ossification center forms as blood vessels and osteoblasts invade the calcified cartilage. The osteoblasts lay down bone matrix, forming trabeculae.
- Secondary ossification centers form in the epiphysis of long bones.
Intramembranous ossification
- In center of ossification, osteoprogenitor cells develop into osteoblasts.
- Osteoblasts secrete organic matrix called OSTEOID.
- The secretion stops and it develops into Osteocytes.
- Calcium and other mineral salts are deposited to calcify the bone.
- After calcification, bone matrix develops into Trabeculae – fuse with one another to create spongy bone.
- Spaces between trabeculae fill with vascularised connective tissue is differentiated into RBM.
- Mesenchyme condenses and develops into the PERIOSTEUM.
- Superficial layers of the spongy bone remains at the center.
hyaline cartilage that covers the epiphysis
acticular cartilage
- type of dense connective tissue that can withstand considerable tension
- no canals, no Haversian system, avascular
- semi-opaque
Cartilage
most common, glossy, weakest cartilage
Hyaline
strongest, serves as cushion to some joints with limited motion
Fibrous
with elastic fibers/some which has some firmness
Elastic
