Page 19 - ASOP ROT Study Guide

Bones are classified into four groups according to their structure.

LONG SHORT FLAT IRREGULAR
Humerus Carpals Skull Bones Vertebrae
Ulna Tarsals Scapula Sacrum
Femur Ribs Coccyx
Tibia Facial Bones
Fibula Jaw Bones
Metacarpals Ear bones
Metatarsal Hyoid Bone
Phalanges
Radius

4 . 3 Bone Tissue

Bones consist of bone tissue, a large number of blood vessels and in certain areas a rich
nerve supply.

Bone tissue consists of bone cells, a non-cellular organic component and an inorganic
component. The non-cellular organic component consists of very strong collagen protein fibers
embedded in a jelly-like matrix called ground substance. The inorganic component consists of
crystals of calcium phosphate (hydroxyapatite) which are deposited within the matrix giving bone
its hardness. The non-cellular material makes up a much greater part of bone tissue than the
bone cells. The collagen fibers are very tough when pulled but they bend easily; The calcium
phosphate crystals are very strong and they can withstand compression, but they shatter when
exposed to excessive bending or impact. The combination of these materials in bone gives it
some of the useful properties of each material.

4 . 3 . 1 Bone growth and development

The terms osteogenesis and ossification are often used synonymously to indicate the process of
bone formation. Parts of the skeleton form during the first few weeks after conception. By the
end of the eighth week after conception, the skeletal pattern is formed in cartilage and
connective tissue membranes and ossification begins.

Bone development continues throughout adulthood. Even after adult stature is attained, bone
development continues for repair of fractures and for remodeling to meet changing lifestyles.
Osteoblasts, osteocytes and osteoclasts are the three cell types involved in the development,
growth and remodeling of bones. Osteoblasts are bone-forming cells, osteocytes are mature
bone cells and osteoclasts break down and reabsorb bone.