BONE FORMATION / OSSIFICATION :-

INTRAMEMBRANEOUS- within membrane
 Ossification takes place in the membranes of connective tissue.
 Cells in the membrane differentiate into osteoblasts,
 A collagen matrix is formed, which undergoes ossification
 So basically, these bone is formed from collagen matrix.
 Mostly flat Bones: maxilla, majority of mandible & cranial vault*

ENDOCHONDRAL – within cartilage
 Bone formation takes place From within a hyaline cartilage
 Cartilage cells are replaced by bone cells,ie. osteocytes replace chondrocytes.
 short and long bones are formed this way
 ethmoid, sphenoid, occipital (synchondrosis of bones of cranial base*)
 Some part of mandible (condylar head region)
 MANDIBLE BONE FORMATION IS BY BOTH endochondral + intramembraneous