The Skeletal System Presentation PDF

# The Skeletal System ## What do you know about the Skeletal System? The Skeletal system is a network of many different parts that work together to help you move. ## What is Skeleton? - The skeleton's protective function alone may be provided by structures situated on the body surface. - The ske...

# The Skeletal System ## What do you know about the Skeletal System? The Skeletal system is a network of many different parts that work together to help you move. ## What is Skeleton? - The skeleton's protective function alone may be provided by structures situated on the body surface. - The skeleton supports the body against the pull of gravity. - It gives the body its shape, allows movement, makes blood cells, provides protection for organs and stores minerals. - It provides a storage site for excess calcium. Calcium may be removed from bone to maintain a normal blood calcium level, which is essential for blood clotting and proper functioning of muscles and nerves. ## Division of the Skeleton These are: Axial and Appendicular Skeleton ### Axial Skeleton The axial skeleton is composed of the skull (29 bones), the thorax (25 bones) and the vertebral column (26 bones). There are a total of eighty bones in the axial skeleton. ### Appendicular Skeleton The appendicular skeleton is composed of the upper extremity and lower extremity bones. There are a total of 126 bones in the appendicular skeleton. ## Classification of Bones There are five classifications of bones in the skeleton: flat, long, short, irregular, and sesamoid. ### Flat Bone Is to protect internal organs such as the brain, heart, and pelvic organs. Flat bones are somewhat flattened, and can provide protection, like a shield; flat bones can also provide large areas of attachment for muscles. ### Long Bone Is to support the weight of the body and facilitate movement. Long bones are mostly located in the appendicular skeleton and include bones in the lower limbs (the tibia, fibula, femur, metatarsals, and phalanges) and bones in the upper limbs (the humerus, radius, ulna, metacarpals, and phalanges). ### Short Bone Is one that is cube-like in shape, being approximately equal in length, width, and thickness. The only short bones in the human skeleton are in the carpals of the wrists and the tarsals of the ankles. Short bones provide stability and support as well as some limited motion. ### Sesamoid Bone Are bones embedded in tendons. These small, round bones are commonly found in the tendons of the hands, knees, and feet. Sesamoid bones function to protect tendons from stress and wear. The patella, commonly referred to as the kneecap, is an example of a sesamoid bone. ### Irregular Bone Vary in shape and structure and therefore do not fit into any other category (flat, short, long, or sesamoid). They often have a fairly complex shape, which helps protect internal organs. ## Types of Bone Tissues ### Compact Bone Tissue Forms the extremely hard outside layer of bones. Compact bone tissue gives bone its smooth, dense, solid appearance. It accounts for about 80% of the total bone mass of the adult skeleton. ### Spongy Bone Tissue Is lighter and less dense than compact bone. Spongy bone consists of plates (trabeculae) and bars of bone adjacent to small, irregular cavities that contain red bone marrow. ### Other Tissues in Bones Besides compact and spongy bone tissues, bones contain several other tissues, including blood vessels and nerves. In addition, bones contain bone marrow and periosteum ### Bone Marrow Is a soft connective tissue found inside a cavity, called the marrow cavity. There are two types of marrow in adults - yellow bone marrow (which consists mostly of fat) and red bone marrow. All marrow is red in newborns, but by adulthood, much of the red marrow has changed to yellow marrow. In adults, red marrow is found mainly in the femur, ribs, vertebrae, and pelvic bones. Only red bone marrow contains hematopoietic stem cells that give rise to red blood cells, white blood cells, and platelets in the process of hematopoiesis. ### Periosteum Is a tough, fibrous membrane that covers the outer surface of bones. It provides a protective covering for compact bone tissue. It is also the source of bone cells.