CA Science Center: Body Worlds (Part Two)
The information found in the captions is derived from the exhibit except those found in parentheses. Those are my own words.
As the above picture comments, these skeletons were once living people who gave permission to use them for scientific and educational purposes. I hope you enjoy the pictures as much as I enjoyed viewing the exhibit, keeping in mind to respect the skeletons and its bones.
Shall We Continue with the Skeleton?
An adult’s skeleton only weighs 15 to 20 pounds, yet, it is stronger than reinforced concrete. The skeletal muscles are attached to the skeleton, creating a system of mechanical levers that convert muscular action into movement. The skeleton tens to become lighter, and therefore weaker with age, a condition known as osteoporosis. Bones also have several other vital tasks. They protect delicate internal organs and store minerals needed in metabolic processes. The bone marrow inside the bones produces blood cells. The main blood cells production sites are in flat bones such as the breast bone, ribs, shoulder blades, and pelvis. The effect can be minimized through regular physical exercise as bone is reinforced where it bears load.
And Explore Its Specific Parts?
The skull protects the brain, gives shape to the head and face, and houses the sensory organs; the eyes, nose, tongue, and at the base of the cranium, the inner ears. The skull is made of 22 single bones. As we get older the loss of bone mass also affects our facial bones, playing a significant part in facial aging.
Feet and toes are crucial for walking upright. They bear and distribute body weight when we walk or run. They also help keep its balance. Each foot has 26 bones and over 100 ligaments. Feet are sometimes said to have “fallen asleep.” This sensation is usually caused by lying awkwardly on a limb’s nerves, or by restricted blood supply to the area. Normal feeling is restored by changing position and allowing blood to recirculate: the numbness is replaced by “pins and needles,” a tingling sensation, as nerves again start sending messages to the brain and spinal cord.
The knee joint links the thigh bone with the tibia, the weight-bearing bone in the lower leg. It bears the greatest load of any joint and there has to be extremely stable. To be stable, the knee needs 13 muscles plus collateral and cross-ligaments. The knee-joint bones are not a perfect fit. To fill the gap, they have two crescent-shaped cartilage wedges. One part of the knee joint is the kneecap, which is held in a sheath of tendons.
Because the knee has to support our body weight, it may suffer severe wear and tear over a lifetime. This damage may cause chronic pain and limit movement. In a worn joint, the cartilage develops cracks that impair its function as a smooth lubricated surface. Such cartilage damage is called osteoarthritis. In severe cases, the cartilage may be almost completely destroyed and the surfaces of the bones may also begin to wear down. Attempts at healing by the bone producing bone growths known as osteophytes. This disease mostly affects people over 50 and is more common in those who are overweight, because of the extra load on their bones. (So in other words, lose some weight to give all your joints a much needed rest.)
The hip joins the torso and legs via the pelvic bones. The pelvis is a flexible ring formed by three major bones: the two hipbones and the rear sacrum bone. Thanks to this ring structure, the legs can handle the torso’s weight. The hip sockets are recessed into the pelvis and cover over half of the thighbone head. The hip is a ball-and-socket joint just like the shoulder, but the hip motion is restricted in favor of greater stability.
A hip replacement may be necessary if a bone becomes severely worn/osteoarthritis, if the neck of the femur becomes fractured, or if any other change takes place in the hip that significantly limits its function. Hip fractures and severe osteoarthritis of the hip are particularly common in older people. The artificial hip mimics both the spherical shape of the head of the femur as well as its angle in relation to the neck of the femur. Its long stainless-steel shaft is cemented into the bone-marrow canal of the femur.
The point at which two bones meet is called a joint. (Anatomy 101) The shoulder is a ball-and-socket joint. It connects the upper arm bone/humerus to the shoulder blade/scapula and has the greatest movement of any joint. Excessive use of our joints, for instance at work or in sport, can cause wear and tear. Joint problems are a significant cause of trouble as we get older. Regular gentle exercise is good for our joints and helps to keep them in working order. (I also advocate stretching, which I need to do much more consistently).
The cochlea is our organ of hearing. The semicircular canals are our organ of balance. Both systems belong to the inner ear and are hidden deep in the temporal bones at the base of the skull. The cochlea is a tube full of liquid. When sound waves travel into our ears, the liquid vibrates, stimulating special sensory cells. These cells convert the vibrations into nerve impulses. Information then is carried along the auditory nerve to the brain, where the signals are interpreted. The semicircular canals have a similar system.
Ossicles are the smallest bones in the body. They are named after their shapes: the hammer/malleus, the anvil/incus, and the stirrup/stapes. They form a bony chain behind the eardrum at the end of the external auditory canal and transmit sound to the inner ear. The ossicles and the eardrum form the middle ear.
The spine is the body’s axial skeleton. It consists of 24 vertebrae, the sacrum, the tailbone, and the intervertebral disks. The intervertebral disks separate the vertebrae and act as natural shock absorbers. And adult spine is S-shaped. This particular shape develops as infants learn to lift and hold their head and to walk, exerting a pulling force with their muscles. In old age, the spine shrinks by as much as 3 inches because of a reduction of bone density called osteoporosis and a shrinkage of the intervertebral disks. Regular physical activity counteracts this process, because strong back muscles will support the spine.
Scoliosis is a sideways curvature of the spine that occurs most often during the growth spurt just before puberty. While scoliosis can be caused by conditions such as cerebral palsy and muscular dystrophy or by improper weight distribution, the cause of most scoliosis is unknown. In many cases, no treatment is necessary.
This concludes the skeleton and bones. I will be posting further pictures of the exhibit pertaining to disease and blood. I will also be posting various tidbits of information from the exhibit that might be interesting.