The Locomotor system of the human body ensures the stability and mobility of the organism. Moving your hand or leg, smiling, closing your eyes and every other movement you do is due to this system. This system contains of the bones and the muscles.
The number of bones in the grown up is 206. Babies have a greater amount of bones, but as they age the bones combine with each other, forming bigger, more stable ones. Muscles are attached to the bones and because of this attachment movement is possible. Usually each muscle is attached to two bones and when it contracts the bones move as well as the body. Contraction of muscle tissue inside the organs creates peristalsis – very important for numerous functions that are essential for the organism. The muscles in your face that let you make mimics have a different way of attachment – they are connected to a bone and to the skin. Because of this when they contract, the skin is moved and the specific mimics are expressed. There are more than 500 muscles in the body.
Bones are made out of mostly inorganic substances that make them hard and stable. Calcium is really important for keeping these features of the bones. In children the amount of organic substances in the bones is higher than in grown ups and this is why child’s bones are less breakable, more elastic. With age the organic substances decrease and the inorganic ones increase which makes them more fragile in elders. Bone tissue just like any other needs oxygen and nutritive substances. These are provided by the blood vessels that enter the bone tissue. In bones there are special canals named Haversian canals. Bone tissue can be compact and spongious. Compact bone tissue is made out of lamels that are regularly placed in a circle around each Haversian canal. The lamels and these canals are parallel to the length of the bone.
Muscles are made out of muscle cells. Muscle cells are long in shape and could be three types, therefore there are three types of muscle tissue – cardiac, skeletal and smooth muscle tissue. Cardiac muscle tissue is found in the heart muscle, responsible for the heart beat, which is essential. Skeletal muscle tissue is found in the skeletal muscles – the ones connected to the bones and letting us perform movements and mimics. Smooth muscle tissue is found in the walls of inner organs, such as blood vessels, bladder, trachea, intestines and others. Muscle tissues are grouped together and around them there is connective tissue called fascia. Each such bundle of muscle tissue, together with other such bundles, are also surrounded by fascia forming the body of the muscle. Muscles also have tendons. These are the parts that connect muscles to the bones. Usually there are two tendons. Tendons are extremely not elastic and hard. They are mainly made out of collagen fibers. Typical of these fibers is that they are slightly elastic ( not more than 5% of their length), but can resist pulling to a really great extent.