Book 4 - Self Instructional Manual for Cancer Registrars - SEER ...

SECTION KTHE SKELETAL SYSTEMThe skeletal system is composed of bones and cartilage. Most of the bones and much of thecartilage form joints which are held together by ligaments of tough, fibrous connective tissue. Jointscan be classified as immovable (synarthrosis), slightly movable (amphiarthrosis), and freely movable(diarthrosis).There are a total of 206 bones in the adult human body. Eighty of these bones form the uprightaxis of the body, the axial skeleton, which is the basic framework of the body. It includes the skull,vertebral column, and the bones (ribs) which encase the thorax. The other 126 bones comprise theappendicular skeleton which is made up of bones that are attached or appended to the axial skeleton:the upper and lower extremities (arms and legs) including the shoulder and pelvic girdles (clavicle,scapula, and hip bones). The main bones that compose the skeletal system can be located in Figures58 and 67.This complex skeletal system has a variety of functions.• It provides a supporting framework for the body.• It affords protection for the vital organs: heart, lungs, brain, spinal cord, as well assensory organs, and soft tissues.• It provides a leverage system for muscle action with the bones providingattachments for the muscles, ligaments,1 tendons,2 and fascia.3• It serves as a storehouse (within the bone) for minerals, and supplies calcium andphosphorus to the blood.• It contains bone marrow which produces millions of red blood cells and thousandsof white cells (hemopoiesis).lligament--a fibrous band of connectivestrengthen joints.tissue that connects bones to bones serving to support andZtendon--a fibrous cord of connective tissue by which a muscle is attached to bone.3fascia--a fibrous sheet of connective tissue covering and separating muscles.343