The human skeleton is comprised of bones, fused or individual. These bones are also supported by ligaments, muscles, tendons, and cartilage. Ligaments are tough, fibrous, dense connective tissues which fasten two bones together to form a joint. The muscles are used to maintain the bones in a good posture, and they are also needed for movement. The muscles are connected to the bones with tendons. Tendons are another types of tough, fibrous connective tissue, which unlike the ligaments who join bones, they join the muscles to the bones. Cartilage is a stiff, but still flexible connective tissue, whose main function is to prevent bone on bone rubbing. Cartilage also makes up certain parts of our body such as our nose, and ears. The actual bones are not logs of solid, but are logs with a honey-combed interior, which is what makes them so light and yet very hard. The outside of the bones, where the blood vessels attach themselves, is called the periosteum. The layer that we see, the white, smooth outside, is called the compact bone. Within this compact bone, there are many layers of cancellous bone, which resembles a sponge, or honeycomb. In most bones, these cancellous layers protect the innermost of the bone, the bone marrow. This is where the cells are created.
The skeletal system serves many purposes. It has many main functions:
1. Structure: the skeleton maintains our body in place, like a wire on which a sculptor places strips of clay. Without the skeleton, our muscles, veins, arteries, and organs would have nothing to hold themselves to, and we would be heaps of meat unable to move.
2. Movement: the joints (where bones are connected with ligaments) and skeletal muscles allow certain bones to move in a certain way. We can do all our movement because of the skeleton and the nervous system which has control over the movement.
3. Protection: the skeleton protects a variety of organs and tissues such as:
-The skull protects the brain, and the eyes.
-The ribcage, spine and sternum protect the heart, lungs, and major blood vessels.
-The spine protects the spinal cord.
The skeleton also protects the digestive system, the ankles, the wrists, etc.
4. Blood Cell Production and Storage: the bones create red and white blood cells as well as storing minerals.
Skeletons of each individual differ slightly. When a baby is born, s/he contains approx. 270 bones, but as the child develops, many bones fuse together, creating less bones. An average adult contains 206 bones. There are also differences between male and female skeletons, as they do not require to do the same actions. The female body has a flatter, larger, and slightly rounder pelvis in order to allow the head of the fetus to pass during childbirth. Even so, the pelvis widens even more during childbirth, which tells osteologists (scientists studying bones), whether the skeleton found on an excavation was a woman, and if she was a mother. Woman also have narrower ribcages and less pronounced cranial features. Men seem to have thicker, and longer limbs and digit bones.
Reference: http://en.wikipedia.org/wiki/Human_skeleton, http://en.wikipedia.org/wiki/Tendon, http://en.wikipedia.org/wiki/Skeletal_muscle, http://en.wikipedia.org/wiki/Ligament, http://en.wikipedia.org/wiki/Bone, http://wiki.answers.com/Q/What_is_the_name_of_a_scientist_that_studies_bones, http://kidshealth.org/kid/htbw/bones.html#, http://en.wikipedia.org/wiki/File:Human_skeleton_front_en.svg, http://en.wikipedia.org/wiki/File:Human_skeleton_back_en.svg, http://hippie.nu/~unicorn/tut/xhtml/