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| Skeletal System |
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| Skeletal system or the skeleton forms the bony framework of the body providing support and protection for some of the soft organs, particularly in the skull and pelvis; acting as levers in movements and providing surfaces for the attachment of the skeletal muscles. In certain parts the framework is supplemented by cartilage. |
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| Study of skeletal system is called as osteology. |
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| Depending on their location, the skeleton is divided into exoskeleton and endoskeleton. |
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| The exoskeletal components are derived either from the epidermis or dermis of the skin. The exoskeletal structures in mammals are the scales or scutes of keratin, horns, claws, nails, hooves, hair etc. |
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| The endoskeletal components are derived from the mesoderm. These constitute the internal framework of the vertebrates. The endoskeleton consists of either boner or cartilage or both. |
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| Human skeletal system consists of 206 pieces of bones and are divided into two main parts: |
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| a) Axial skeleton and |
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| b) Appendicular skeleton, each having subparts. |
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| Axial skeleton occupies the longitudinal central axis of the body. It includes four structures namely |
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| i) Skull in the head, |
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| ii) Vertebral column in the neck and trunk |
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| iii) Sternum, and |
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| iv) Ribs in the thorax. |
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| Appendicular skeleton is placed in the side axes. It comprises of |
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| i) pectoral and pelvic girdles |
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| ii) limb bones. |
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| Human Skeleton |
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