What are Bones for?
The skeleton must be able to withstand a lot of strain during various types of movement. The femur (thigh bone) is the largest bone in the human body and can support an astonishing 1,500 tons. The knees, which absorb the pressure of tensile forces and bending, can withstand the second highest strain. Because of their unique structure and composition, they are very robust while at the same time being highly elastic.
What are Bones made of and what types of Bone are there?
Bones (or bone tissue) are first and foremost in the category of supportive and connective tissue, even if they represent a particularly hard (i.e. stable) form of tissue. (On a side note, teeth are not included in this category, as they are fully in a category of their own.) There are approximately 206 bones in the human body; it is not possible to give an exact number, because some people can have a different number of small bones in the spinal column, hands and feet.
There are various categories or types of bone. Long bones, which are characterised by a long shaft and two bone ends, are found in the upper arm and forearm as well as in the thighs and calves. There are also plate bones, which are flat (as the name suggests), such as the shoulder blade and the cranial bone at the top of the skull. In addition, there are short bones (e.g. in the wrist), sesamoid bones (small and round bones such as the kneecap), air-filled bones (e.g. the frontal bone) and irregular bones such as those in the spine, which do not fit into any of the above categories.
Looking from the outside in, bones are surrounded by connective tissue. Internally, you will find a sponge-like structure made from several tiny bones; bone marrow can be found in the space between these. In its sponge-like form, bending, impact, and similar forces can be absorbed. Bones also have a high mineral and salt content, mainly calcium. As salts themselves are made from a hard material, these constitute strength and enable resistance to pressure and strain.
Duties and functions of Bones
As there are many types of strain that we put our bodies under, each bone is constructed in such a way that it can absorb the impact from a specific type of movement. Each bone has its own function.
Bones can perform several functions at once and provide protection from the inside out. For example, the rib cage is a protective shield for the heart and lungs, whereas the cranial bone at the top of the skull acts as a strong fortification around the brain. Moreover, the bones help the transmission of force during movement and red blood cells are even produced in bone marrow.
Even our ancestors in the stone age understood the varied possible uses for animal bones as tools, needles and jewellery; and although it is clear that the bones in the human body undertake completely different functions, the fact that bones were used in these ways proves how robust bones are and how much power they can withstand. The skeleton really is a hidden internal helper that supports us, day in and day out.