Skeletal system

SKELETAL SYSTEM

Skeletal system is a system of external and internal, living or dead, hardened structure which forms supported, protective and jointed framework of the body. The skeleton system is responsible for movement or locomotion of various body parts.

TYPES OF SKELETAL SYSTEMS

(I) Exoskeletal system: The skeleton which is external is called exoskeleton. It is rigid, protective and supportive covering present outside the body. Exoskeleton is made up of hard structures or dead tissue present in both vertebrates and invertebrates.

(II) Endoskeletal system: The skeletal system present inside the body of the organism is called endoskeletal system it is hard supporting structure Framework which occur inside the body of both vertebrates and invertebrates. Endoskeletal  in case of vertebrates is made up of bone and cartilage.

On the On the basis of different skeletal structure present in the body of the organism, endoskeleton is divided into two principal division:

(I) Axial skeleton: The axial skeleton runs along the middle longitudinal axis of the body. It  comprises 80 bones which are distributed along the main axis and form for structures such a skull, vertebral column, sternum and ribs.

(II) Appendicular skeleton: The Appendicular skeleton system includes the skeleton of limbs, the pectoral and pelvic griddle which support and suspend the skeleton of limbs from the vertebral column. The griddle which support the forelimbs is called pectoral girdle and the griddle with support hindlimbs is called pelvic griddle. Hence the bone of the limbs, pelvic griddle and pectoral girdle constitutes the appendicular skeleton. It is situated at the lateral sides which extended outward from the principal axis.                            

TYPES OF BONES

(I) Cartilaginous or replacing bone:

These bone develop from pre-existing cartilage. These are also called endochondral bone example humerus, femur.

(II)Investing or dermal or membrane bone:

These bones develop in the dermis of the skin thin plates and sink to get attached over original cartilage example frontal, nasal bone of the skull.

(III)Sesamoid bone:

These bones are formed in tendons are the joint example patella.

(IV) Visceral bone:

These bones are formed in organs and associate from rest the rest of the skeleton.

JOINTS

Joints are the structural arrangement where two bones articulate that is meet each other. The framework of the body consists of separate skeletal elements which are joint or articulate with one another by different types of joints. The joints are essential for the movement of different skeletal structure that is all the bones present in the body produce movement due to the movement of these joints. Locomotory movement occur due to this joint , where these act as lever or fulcrum.

FACTS

(I)At the time of the birth these are approximately 300 bones. After sometime during adulthood some bone fuses to  and form 206 bones.

(II)The only bone in our body which does not articulate with other bone is hyoid bone.

(III)About one person in 20 has one extra pair of ribs, making 13 pairs instead of 12 pairs.

(IV)The base of skull has a large opening called foramen magnum.

(V) Hardest connective tissue is bone.

-FRACTURE BREAKAGE OF BONE, EITHER COMPLETELY OR INCOMPLETELY

(I) Simple fracture:

 fracture breaking the bones into to fully separate parts with little damage to the surrounding tissue and no break in the overlying skin.

(I)Green stick fracture:

a break of the bones in the form of only track, the broken part still holding together.

(III) Comminuted fracture:

 in this fracture, the bone is broken into more than two fragments with some of the fragment losing any connection with the blood circulation.

(IV)Compound fracture:

 the broken ends of the fractured bone protrude through skin.

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