I. Function
A. Support
B. Protection
C. Levers – movement
D. Storage
E. Blood cell production – hematopoiesis
II. Histology
A. Introduction – bone or osseous tissue contains a great deal of intercellular substance (matrix) surrounding widely separated cells. Inteercellular substance contains:
1. mineral salts (calcium phosphate and calcium carbonate) Ca(PO4)2 + (OH)2 and Ca CO2. Hydroxyapatites (67% of bone).
2. Collagenous fibers (33% of bone) – salts are deposited on collagenous fibers
B. Anatomy of lone bone
1. Diaphysis – shaft of long portion of bone
2. Epiphysis – extremities or ends of bone. (metaphysic – region of mature bone where the diaphysis joins the epiphysis.
3. Articular cartilage – hyaline cartilage covering epiphysis
4. Periosteum – dense white, fibrous covering of bone
a. fibrous layer (outer) containing blood vessels, lymphatic vessels and nerves.
b. Osteogenic layer (inner) contains elastic fibers, blood vessels, and osteoblasts (forms new bone during growth or repait)
5. Medullary or marrow cavity – space within the diaphysis containing yellow marrow (fat storage – fatty material)
6. Endosteum – layer of osteoblasts that line the medullary cavity and contain scattered osteoclasts (may play a role in removal of bone).
7. Compact or dense bone
a. Volkmann’s canals
b. Haversian system or osteon
(1 )lamellae
(2 )lacunae
(3 )canaliculi
(4) interstial lamellae – areas between haversian systems
8. Spongy or cancellous bone –
a. trabeculae – b. red marrow
III. Ossification – process by which bones form in the body
A. Introduction
1. The “skeleton” or human embryo is composed of either fibrous membranes or hyaline cartilage
2. Both are shaped like bone
3. Ossification begins about 6th week of embryonic life and continues throughout adulthood
4. Two kinds of bone formation
a. Intramembranous ossification – formation of bone directly on or within the fibrous membranes
b. Endochondral ossification – formation of bone in cartilage,
5. The first stage in the development of bone is the migration of embryonic connective tissue cells (mesenchymal cells) into the area where bone formation is about to begin. Soon these cells increase in number and size. In some skeletal structures they become chondroblasts; in others, some become osteoblasts. Osteoblasts will form bone tissue by intramembranous or endochondral ossification.
B. Intramembranous ossification (skull)
1. Bone formation – flatbones of the roof of the skull, parts of the
