Ossifications Lecture Note | The University Of Western Ontario

University:
The University Of Western Ontario
Course:
ANAT 2200B | Systemic Anatomy of the Human Body
Academic year:

2022
Views:

306

Pages:

3
Author:

Kyuwon J.

Ossifications ● Bone formations typically involve… ○ osteogenic cells ○ Organic matrix ■ osteoids ○ Mineralization of calcium salts ● Begin in fetal level, continues until early adulthoods Ossification mechanisms ● Intramembranous Ossification ○ directly from mesenchymal tissues ○ no cartilage model ○ flat bone in skull ■ vault ○ Facial bones ○ Mandible ○ Partially clavicles ○ Mesenchymal cells ⇒ osteoblasts ⇒ Osteoblasts on osteoids ⇒ osteoid mineralization ⇒woven bones ⇒ Remodeling ⇒ lamellar bones ○ Tends to be early and rapid ○ production of compact and cancellous bones ○ used for cranial expansions ■ Craniosynostosis ● premature fusion leads to increased ICP ■ Delayed ossifications ● soft skull ● Craniotabes ● Endochondral Ossifications ○ Pre-existing hyaline model ○ long bones ○ vertebrae ○ Pelvis ○ Base of skull Feature Primary Secondary Location Diaphysis Epiphysis Time In utero Postnatal Function Shaft formation End growth Marrow cavity Present Absent ■ Cartilage model formations ● Mesenchymal cells ⇒ chondroblasts ● hyaline cartilage formations ■ Primary ossification center ● in diaphysis ● 7-8weeks IU ● Blood vessels able to sneak in cartilage ● osteoblase will replace cartilage with bones ■ Secondary Ossification centers ● epiphyses ● after births ● Cancellous bone formations ■ Persistence in Cartilages ● Articular cartilage Feature Intramembranous Endochondral Cartilage model No Yes Growth plate Absent Present Bones Flat skull Long bones Disorders Craniosynostosis Achondroplasia