TYPES OF BONES

Bones can be classified on various bases. There ar five main types of bones, based on shape-(I) Long bones -They have greater length than width, e.g. bones of thigh, leg, arm, forearm, etc. (2) Short bones -These are cube shaped, e.g., wrist and ankle bones (3) Flat bones -They are thin, plate-like, e.g., bones of the skull, breast bones, etc. (4) Irregular bones- They have complex shapes, e.g., vertebrae of the backbone. (5) Seasmoid bones - These are shaped like a "seasame" seed, e.g., knee cap, palm and sole. They develop in certain tendons where there is considerable friction, tension and physical strees.

  An additional type of bone, which is classified by location, instead of shape is sutural bone. These are small bones located within joints, between cranial bones.

Further, there are two types of bones, on the basis of development (1) Membranoous bones or dermal bones, which are formed by intra-membranous ossification, and (2) Cartilagenous bones, which ossify from cartilage model.

On the basis of region, there are four more types of bones: (1) Compact bone -They have more bone tissue than space  (2)Spongy bone -They have more empty space than bone tissue (3) Lamellar bone -These are made of thin plates or lamellae and (4) Fibrous bones -They are made of more fibres. In humans, these are found only in the foetus.