BONES
Bone is one-third connective tissue. It includes all 206 bones of body.
It is impregnated with calcium salts which constitute the remaining two-thirds part.
Functions of Bones:
1. Give shape and support to the body, and resist any forms of stress.
2.
Provide
surface for the attachment of muscles, tendons, ligaments etc.
3.
Serve
as levers for muscular actions.
4.
The
skull, vertebral column and thoracic cage protect brain, spinal cord and
thoracic and some abdominal viscera, respectively.
5.
Bone
marrow manufactures blood cells.
6.
Stores
97% of the body calcium and phosphorus.
7.
Contains reticuloendothelial cells which are phagocytic in nature and take part in
immune responses of the body.
8. Larger paranasal air sinuses. Ex. Ethmoidal sinuses affect the timbre of voice.
Classification of Bones:
A. Types of bone on the basis of shape.
1.
Long
bones
Ex: humerus, radius,
ulna.
2.
Short
bones
Ex: tarsals, carpals.
3.
Flat
bones
Ex: sternum, ribs.
4.
Irregular
bones
Ex: vertebrae, facial
bones.
5.
Sesamoid
bones
Ex: patellae.
6.
Accessory
bones
Ex: cervical ribs.
B.
Types
on the basis of development.
1. Membrane bone (Ex: frontal bone)
i. Cartilaginous
bones
Ex: femur.
ii. Membrano-
cartilaginous bones
Ex: clavicle.
2. Somatic bones (Ex: most of the bones are somatic)
i. Visceral bone
Ex: hyoid bone.
C.
Types on the basis of regional.
1.
Axial
skeleton
Ex: includes skull,
vertebral column and thoracic cage.
2.
Appendicular
skeleton
Ex: upper and lower limb.
D. Types on the basis of structural.
1.
Compact
bone
2.
Cancellous
or Spongy bone
Parts of a young growing bone.
1. Epiphysis
2. Diaphysis
3.
Metaphysis
4. Epiphyseal plates
1.
Epiphysis:
The ends and tips of a bone which ossify from secondary centres are called Epiphysis.
2.
Diaphysis:
It is the elongated shaft of a long bone which ossifies from a primary centres
of ossification.
3.
Metaphysis:
The epiphyseal ends of a diaphysis are called metaphysis.
4.
Epiphyseal
Plates: It separates epiphysis from metaphysis.