BONES
The bones are the hard structure ,Which form the rigid framework the body.
Bone is a highly vascular mineralized connective tissue consisting of cell and dense intercellular organic matrix impregnated with organic salts. The organic material mainly consist of collagen fibers and form one third of the bone.
The inorganic material mainly consist of calcium phosphate and traces of other salts. It provides hardness and rigidity to the bone and makes it radiopaque in x-ray film.
FUNCTION
Bone give shape and support to the body ,and resist any forms of stress.
These provide surface for the attachment of muscle ,tendons,ligaments.
These serve as levers for muscular actions.
Bone marrow manufactures blood cells.
Bone store 97%of the body calcium and phosphorus.
Bone marrow contains reticuloendothelial cells which are phagocytic in nature and take part in immune responses of the body.
The skull ,vertebral column and thoracic cage protect brain , spinal cord and thoracic and some abdominal viscera ,respectively.
some bones around the nose contain large cavities filled with air (paranasal air sinuses which affect the timber of the voice).
CLASSIFICATION OF THE BONE
According to shape
According to the structure
According to the development
CLASSIFICATION ACCORDING TO THE SHAPE
Depending on the size and shape. the bone are classified into 7 type.
• Long Bones
• Short Bones
• Flat Bones
• Irregular Bones
• Pneumatic Bones
• Sesamoid Bones
• Accessory Bones
Long bones
Long bone are those in which length exceeds the breadth and thickness.
The long bone are two types.
Typical long bones
Miniature/short long bone
Short bones
Short bones are small in size and usually cuboidal in shape , presenting six surfaces. These bones are found in wrist (carpal bone ) and foot (tarsal bone).
Flat bones
Flat bone are flat and shallow plate-like bone.
They form boundaries of certain body cavities. the example of the flat bone frontal, parietal ,occipital ,scapula, ribs, sternum.
Irregular bones
Irregular bone are highly irregular shape ,hip bone vertebrae bone forming base of skull.
Pneumatic bones
Pneumatic bone are a variety of irregular bone which contain air filled cavity. These bones are mainly located around the nasal cavity.
Example maxilla ,frontal ,sphenoid and ethmoid bones.
Sesamoid bones
These are bony nodules found embedded in the tendons or joint capsules.they have no periosteum and ossify after birth. Ex. Patella.
Accessory bones
These bones are not always present. These may occur as ununited epiphysis developed from extra centres of ossification. Ex. Sutural or wormain bones.
CLASSIFICATION ACCORDING TO THE STRUCTURE
Microscopically the architecture of bone may be compact or cancellous.
Compact bone Compact bone is dense in texture like ivory ,but is extremely porous. It is best developed in the cortex of the long bone.
Cancellous bone The cancellous bone is a mesh work of bony spicules.it consist of interconnecting road and plates of bone called trabeculae.
CLASSIFICATION ACCORDING TO THE DEVELOPMENT
According to the process of the bone development. The bones are three type.
Membranous bones are developed by membranous ossification.
Cartilaginous bone are developed by endochondral ossification.
Membrano-cartilaginous bone developed by both membranous and endochondral ossification.
Parts of growing young long bone
Epiphysis
Diaphysis
Metaphysis
Epiphysis plate
Epiphysis these are ends of long bones which ossify from secondary centers.
Diaphysis It is the elongated part of bone between the metaphysis. It develops from primary ossification center.
Metaphysis the end of diaphysis toward the epiphyseal cartilage is called metaphysis.
Epiphysis plate Epiphysial plate separates epiphysis from metaphysis. Proliferation of the cells in this cartilaginous plate is responsible for lengthwise growth of a long bone.
