Date post: | 18-Jan-2016 |
Category: |
Documents |
Upload: | augustus-shields |
View: | 221 times |
Download: | 0 times |
BONE STRUCTURE & GROWTH
Anatomy of a Long Bone
Epiphysis – ends Mostly spongy bone
Diaphysis – shaft Made of compact bone Center is medullary cavity Contains yellow bone
marrow (mostly fat) in adults, red marrow in children (makes blood cells).
Bone Tissue – Compact Bone
Made of osteons Run parallel to bone
& support weight Center is Haversian
canal – carries blood vessels & nerves
Volkmann’s canal connects Haversian canals
Bone Tissue – Compact Bone
Lacunae – cavities containing trapped bone cells (osteocytes)
Lamellae – rings around central canal, site of lamellae, reinforced with collagen
Canaliculi – tiny canals connecting lamellae
Bone Tissue – Spongy Bone
Made of needle-like projections called trabeculae
Sandwiched between compact bone
Filled with red bone marrow in some bones
Types of Bone Cells
Osteoblasts – Bone forming cells
Osteocytes – Trapped osteoblasts
Osteoclasts – Bone destroying cells, secrete digestive enzymes for remodeling or calcium needs.
Bone Formation (Ossification)
1. Chondrocytes produce cartilage.
2. Osteoblasts cover cartilage with bone matrix.
3. Cartilage is digested away, opening medullary cavity
Bone Growth
Many bones fuse as we age, replacing cartilage with bone
In long bones, the remaining cartilage is the epiphyseal plate
Bone Remodeling
Bones grow or are remodeled in response to forces acting upon them.
Bone Repair
1. Broken blood vessels form clot (hematoma)
2. Living splint made of collagen & cartilage forms (fibrocartilaginous callus)
Bone Repair
3. Osteoblasts form bony callus of spongy bone
4. Osteoclasts remodel to make permanent patch