The arrangement of the individual bones is as precise, orderly and purposeful as the full skeletal system itself, and their distribution from top to bottom is extremely balanced. Most of the bones in our body are structured in a symmetrical fashion. That is, many of our bones are matched on each side of the body. This matched design allows us to balance and stabilize ourselves in the face of the various forces that act on our bodies. Although we will be discussing only the skeletal system, keep in mind that the sensory and balance organs of the nervous system, the muscles, and the bones work together to help achieve this stability. Let's start at the top and work our way down the major parts of the skeleton!

The skull, the "top" of the skeletal system, has 29 bones that are fused together to form the cranium, or brain case, the face, and the ear bones. The only part of the skull that can move freely is the jawbone. The spine, to which are attached the pectoral (shoulder) girdle, rib cage and the pelvic (hip) girdle, has 26 vertebrae. The ribs number 24, 12 on each side. The two girdles, so named because of their shape, mark the upper and lower limits of the body's trunk, or central area. From them, respectively, stem the bones of the upper and lower limbs, the arms and the legs, respectively. Each limb has 30 bones apiece. Of the 60 bones in the two upper limbs, all but 6 are concentrated in the hands and wrists; of the 60 bones in the 2 lower limbs, all but 8 are concentrated in the ankles and feet. Thus, appropriately, more than half of all the bones in the body support those parts of our bodies that maintain the busiest daily work schedule - our extremities.

The femur is not, by any means, the only anti-gravity bone in our bodies but it is the largest. The spine, pelvic girdle, tibia (lower leg), and the bones of the foot (particularly, the talus and calcaneus bones) are all important in our day-to-day "struggle" to stand and move against gravity.

Another superb example of how each bone was designed with a purpose is the vertebrae of the spinal column. To help bear the weight of the body, it is formed like a solid cylinder, but it actually consists of alternating layers of bone and cartilage. These compressible cartilage disks between the vertebrae absorb shock and keep the vertebrae from grinding together when the spine bends. At the back of the bony cylinder, a ring permits passage of the spinal nerve cord, and also serves to protect it. At the back of the ring are three sharp projections, or spurs, which join with the ribs and anchor the muscles of the back. The flexibility of the spine and its ability to stretch and compress contribute to the actual height changes that occur to all of us during the day. In fact, when you have reached the exciting time in your life when you have begun to drive a car, notice how you must adjust your rear-view mirror upwards in the morning and then read just it downwards in the evening. This happens because, after a full day of fighting off gravity, you actually shrink in size! Let's discuss how the absence of gravity might affect your height as well.