More than 200 bones make up the human skeleton, and they all perform a variety of tasks. But the most basic function of all of them is to support and protect the human body and its vital contents. Not all bones look the same, and not all perform the same function. There's even one bone that doesn't even attach to any other bone. Let's discuss some of the different types of bones one can expect to find in the human body.
Long bones; the bones of mobility.
Long bones, the "bones of mobility," are the ones in our extremities, the arms and legs in particular. These are typically referred to as the long bones of the body. In the upper extremities, the bones include the humerus (upper arm bone), radius and ulna, which make up the forearm. The combination of these bones, and the joints that attach them to the shoulder and wrist respectively, allow for an extremely wide range of motion and versatility. Activities such as lifting, pushing, pulling, swimming can all be attributed to the long bone structures in the arms. Similarly, the long bones of the lower extremities are equally important and equally functional. The lower extremity is made up of the femur (thigh bone), tibia and fibula (which make up the lower leg). These bones are responsible for standing erect, running, waking, jumping and all other functions of locomotion. Bones of the hands, feet and fingers are also long bones and help to provide function and mobility to the hands and feet, for gripping (hands) and for walking and balance (feet).
Short bones; bones of support and stability
The short bones of the skeleton are typically provide support and stability. The most common examples are the bones of the wrist and the midfoot. The bones of the wrist are called carpal bones and the ones in the feet are called the tarsal bones. The tarsal bones are a means of support and stability, connecting the longer, metatarsal bones of the foot to the structures of the hind foot and ankle, thus stabilising the middle if the foot. Similarly, the carpal bones of the wrist provide stability to the hand by connecting the longer, metacarpal bones to the radius and ulna of the forearm. These bones are typically rather sturdy because of their stout, compact design.
Flat bones; The "protectors"
The human skeleton possesses many flat bones and their primary function is to protect the body's vital organs from injury. Examples of flat bones include the scapulae (shoulder blades), sternum (breast bone), ribs, the skull and the flat bones of the pelvis. The pelvic bones protect the lower intestines, bladder and the uterus in females. The ribs protect the lungs, and to a lesser extent, the liver, spleen and kidneys. The sternum, along with the ribs, offers primary protection of the heart. In addition to protecting vital organs, these bones also provide attachment points for muscles. A good example of this is the shoulder blade where muscles of the posterior torso and upper shoulder areas attach.
Irregular bones; In a class by themselves
Quite a few bones are shaped in such a way as to exclude them from any of the previously mention classifications, mainly because of their irregular shape. Examples of these irregular bones include the sacrum and coccyx (tailbone area), the mandible (jawbone) and the many vertebrae that make up the cervical (neck), thoracic (chest and midback) and lumbar spinal columns. Vertebrae are responsible for the protection of the spinal cord and nerves, as well as connecting the skull to the neck and the pelvis to the lower back area. These bones are, in essence, what enables us to stand upright.
Sesamoid bones; the unheralded tendon protectors.
Everyone knows what a knee cap is. So too, do they know what the ball of the foot is. Rare is the person that knows what type of bone the knee cap (patella) and the bones in the ball of the feet are. The patella, or knee cap, is a large sesamoid bone. It's the mobile structure in the front of the knee that hurts like heck when it gets banged on a table edge. The primary purpose of the patella is to protect the tendons (patellar and quadriceps tendon) from injury and damage during the process of bending the knee. It also serves as a positive leverage point for the knee when extending it. The small bones on the underside of the big toe, and embedded into the tendon there, are also sesamoid bones and server literally the same purposes. They enable the big toe to hyperextend without causing injury or damage to the tendons located there. There are usually two per foot.
The hyoid bone; The "Unique One"
There is one rare, interesting bone in the body that defies most descriptions. It is a bone that, unlike any other, does not connect to any other bone. The hyoid bone is in the front of the neck and lies in front of the larynx, or windpipe. It protects the vocal cords and is "suspended" in its location by soft tissue attachments.