Skeletal System:

The adult human skeletal system consists of 206 bones, as well as a network of tendons, ligaments and cartilage that connects them. The skeletal system performs vital functions - support, movement, protection, blood cell production, calcium storage and endocrine regulation - that enable us to survive.

Animals with internal skeletons made of bone, called vertebrates, are actually the minority, as 98 percent of all animals are invertebrates, meaning they do not have internal skeletons or backbones. Human infants are born with about 270 bones, some of which fuse together as the body develops. By the time we reach adulthood, we have 206 bones, according to Arizona State University's School of Life Sciences.

The skeletons of adult males and females have some variation, primarily to accommodate childbirth. The female pelvis is flatter, more rounded and proportionally larger. A male's pelvis is about 90 degrees or less of angle, whereas a female's is 100 degrees or more.

While they become brittle when outside of the body, bones are very much alive inside the body, being fed by a network of blood vessels from the circulatory system and nerves from the nervous system, according to Healthline.

A typical bone has a dense and tough outer layer. Next is a layer of spongy bone, which lighter and slightly flexible. In the middle of some bones is jelly-like bone marrow, where new cells are constantly being produced for blood, the Merck Manuals noted.

Teeth are considered part of the skeletal system but they are not counted as bones. Teeth are made of dentin and enamel, which is strongest substance in your body. Teeth also play a key role in the digestive system.

The skeletal system has two distinctive parts: the axial skeleton and the appendicular skeleton, according to the U.S National Library of Medicine(NLM).

The axial skeleton, with a total of 80 bones, consists of the vertebral column, the rib cage and the skull. The axial skeleton transmits the weight from the head, the trunk and the upper extremities down to the lower extremities at the hip joints, which help humans maintain our upright posture, the NLM noted.

The appendicular skeleton has a total of 126 bones, and is formed by the pectoral girdles, the upper limbs, the pelvic girdle and the lower limbs, according to the NLM. Their functions are to make walking, running and other movement possible and to protect the major organs responsible for digestion, excretion and reproduction.

Study of the skeletal system

Orthopedics is the medical specialty responsible for treating entire skeletal system. In the United States, orthopedic surgeons have typically completed four years of undergraduate education and four years of medical school. They then undergo residency training in orthopedic surgery. The American Board of Orthopaedic Surgery oversees the certification process for this specialty. Many go on to further specialize in specific areas, such as the spine, hand or sports injuries.

Milestones

Humans have been dealing with injuries and disease from the beginning of time. Some important milestones in the history of orthopedics include:

• Hippocrates, the ancient Greek father of medicine, develops splints for fractures of the tibia.
• During the Roman era, Galen (199-129 B.C.) describes the skeletal system and the surrounding muscles. Medical experts of the time also develop the first artificial prostheses.
• Ambroise Pare (1510-1590), the father of French surgery, develops techniques for amputations and artificial limbs.
• Antonius Mathysen (1805-1878), a Dutch military surgeon, in 1851 invents the plaster of Paris (POP) bandage. A POP cast remains the primary method of fracture immobilization today.
• In 1895, Wilhelm Conrad Roentgen accidentally discovers an image cast from his cathode ray generator, projected far beyond the possible range of the cathode rays. He wins the Nobel Prize for Physics in 1901 for his discovery of X-rays.
• Sir Reginald Watson-Jones (1902-1972) publishes "Fractures and Joint Injuries" in 1940, which remains a standard reference for several decades.
• In 1949, H. Lowry Rush (1879-1965) uses stainless steel pins to treat long bone fractures.

Information Taken from: https://www.livescience.com/22537-skeletal-system.html