The skeletal system is composed of all the bones found in the body, including the joints that connect the skeletal system. The skeletal system protects all the internal organs of the body and provides a framework that permits the body to stand up and move without difficulty. The bones store minerals that the body utilizes to maintain optimum health and manufacture cells. The muscles in combination with the skeletal system produce movement throughout the body. Without the protection of the skeleton, even an insignificant impact in any part of the human body could damage most vital organs.
The skeletal system is constructed of two hundred and six diverse skeletal bones which are classified into four different shapes, such as short bones like the ones found in the wrist or ankle; long bones, such as the femur; flat bones, including the skull and the scapula; and irregular bones like the ones forming the vertebrae. There are two distinct forms of bone tissue: compact bone and cancellous bone. Compact bone is dense, smooth and very strong, while cancellous bone is spongy and weightless. Both types of bone tissue contain living cells which aid at making reparations any time a bone is injured or broken.
Every long bone includes a central shaft known as the diaphysis and two ends called epiphyses. The central shaft is made up of compact bone and is covered with a membrane of living cells known as periosteum to which tendons and muscles connect. Within the central shaft is the medullary cavity which contains bone marrow. Bone marrow stores fat, manufactures blood cells and plays an essential role in the body´s immune system.
The skeletal system if divided into two distinct divisions: the axial skeleton and the appendicular skeleton. The axial skeleton, which consists of 80 bones, is composed of the skull, the vertebral column, and thorax. The appendicular skeleton, which comprises 126 bones, includes the bones of the shoulders, upper extremities, hips, and lower extremities.
The upper extremities are connected to the upper extremities (arms) by the shoulder girdle (scapula and clavicle). The arms are composed of the humerus in the upper arm; the ulna and radius in the forearm; and the wrist and hand, which include 27 distinct bones. The axial skeleton is connected to the lower extremities (legs) by the pelvic girdle (hip bones). The strongest and heaviest bone in the lower extremities is the femur. The femur is connected to the fibula and tibia which in turn are connected to the foot and ankle. The patella is a small bone between the femur, the tibia and fibula.
The ankle and foot comprise 26 bones and 33 joints which together enable the entire body system to stand, walk, or run, as well as to carry all body weight. The skeletal system of an average adult weights a little bit less than ten kilograms. The skeletal system if compared to materials such as steel or concrete, results of a higher durability, as it is stronger than concrete and even harder than steel, moreover, it can repair itself, resulting in an appropriate structure framework for the protection of the human body