Essay Preview: The Skeleton
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Have you ever wondered how many bones are in the human body, or why do bones break or why there so many? Questions like that only take some time to research and a little determination.
The size and location: There are normally 300+ bones in the human body when born. As time goes on and we grow larger, some of the bones fuse together creating stronger and larger bones. By the time we are fully grown and our bones are done shifting, there are 206 bones left. The bones main function is to support all parts of the body and protect the brain and organs. The skeletons are part of the circulatory system; the bone marrow in the bone helps
to produce red blood cells.
Harm/Diseases: When calcium is lost in the bones the bones release some of the vital calcium that is needed and quickly become weak and brittle, therefore they are easily broken. Fractures can also occur in bones very easily. Bones may be made of strong material, but even tough stuff can break if enough force is applied. When a bone breaks, it is called a fracture. Another type of harm to bones is bone cancer. Cancer that begins in the bone is called primary bone cancer. Primary bone cancer is relatively uncommon in comparison with secondary or metastatic cancer. Metastatic cancer occurs initially in another organ and then spreads to bone tissue.
Neck: Each collar bone is shaped like a rod and slightly like an S. It is horizontal and coherent with the upper end of the breastbone, just above the first rib. The sideways part articulates with the acromium. The collar bones support the shoulder blades in front and keep the shoulder blades back so that the arms can hang on the left and right side of the body. They stop the pectoral girdles from getting out of joints easily and sufficient movement of the shoulders.
Shoulders: The shoulder blade is a flat triangular bone that stretches from the shoulder to the spine. On the back side it has a bony edge for the attachment of the muscles. The bony ridge forms a major projection above the shoulder joint. Beneath the collar bone of the shoulder joint, is another bony projection of the shoulder blade that attaches the muscles. The upper corner of the shoulder blade ends in the glenoid, which fits the head of the upper arm bone, making a ball and socket joint.
Arms n Hands: The arm can be divided into five main parts: an upper arm bone, the forearm, which is the radius and ulna, the wrist, the fingers and the palm of the hand.
The upper arm is one long bone, which consists of a hemi-spherical ball which fits into the socket of the shoulder blade to form the shoulder joint. The lower end of the humerus forms a shallow ball and socket joint with the radius and a hinge joint with the ulna in the elbow.
The Forearm (Radius and Ulna) The two long bones of the forearm are known as the radius and the ulna. The ulna is the larger of the two bones and is situated on the inner side (i.e. the little finger side) of the forearm. The upper end of the ulna articulates with the lower end of the humerus forming a strong hinge joint in the elbow region. The lower end of the ulna is slender and plays a minor role in the formation of the wrist joint. The radius is situated on the thumb side of the forearm. Its upper end articulates with both the humerus and the ulna. The broad, lower end of the radius forms a major part of the wrist joint, where it articulates with the wrist bones (carpals). The radius also allows the forearm to be rotated. The radio-ulnar joints are pivot joints in which the moving bone is the radius. As the head of the radius pivots at these joints, the lower end of the radius moves round the lower head of the ulna. The Wrist The wrist consists of eight carpal bones. These are small, short bones that are arranged in two rows of four. They have articulating facets which allow them to slide over one another.
The Palm of the Hand The palm is supported by five long metacarpals. The metacarpals articulate with carpals at one end and with the phalanges at the other end. The Fingers The fingers are made up of fourteen phalanges. There are three phalanges in each finger but only two in the thumb. The Pelvic (Hip) Girdle. The pelvic girdle consists of two large, sturdy hip bones. Each hip bone consists of three fused bones namely the