Anatomy Lec 2 PDF

The anatomical position is characterized by all of the following except: a. palms facing posterior b. thumbs pointing laterally c. face pointing anteriorly d. body standing upright A vertical plane through the body dividing it into right and left is termed: a. mid-sagittal b. l...

The anatomical position is characterized by all of the following except: a. palms facing posterior b. thumbs pointing laterally c. face pointing anteriorly d. body standing upright A vertical plane through the body dividing it into right and left is termed: a. mid-sagittal b. lateral c. transverse d. frontal The elbow is _____ to the wrist: a. distal b. lateral c. ventral d. proximal The heart is ____ to the lungs: a. superior b. dorsal c. medial d. lateral  Skeletal System Skeletal system includes bones (hard), cartilage (rubbery) ,and joints in-between them. (A)Bones Bone is a living tissue capable of changing its structure (grow and repair itself after injury). bone is hard because of calcification of its extracellular matrix.  Functions of the bone: Bone forms the supporting framework of the body. It gives attachment to the muscles and act as levers essential for locomotion. It gives protection to the contained or underlying structures e.g. the skull protects the brain and the thoracic cage protects the heart and the lungs. Bone acts as storehouses for calcium and phosphorous. It acts as factories for the blood cells which are formed in the bone marrow.  Classification of bones : The adult skeleton is formed of 206 bones, they are classified according to: a) Position. b) Shape. Types Of Bones According To Position According to the position of the bone in the skeleton ,it can be described in two main classifications: 1)Axial Skeleton 2)Appendicular Skeleton.  Types Of Bones According To Shape 1-Long bones: They are : a)Typical long bones: e.g. bones of the proximal and distal segments of limbs, they are characterized by: having two ends and shaft. The shaft contains medullary cavity. b)Modified long bones: e.g. clavicle, is characterized by: having two ends and shaft.The shaft contains no medullary cavity. c) Miniature long bones: e.g. metacarpal & metatarsal, they are characterized by having one end only. 2-Short bones: They are generally cubical in shape e.g. carpal & tarsal bones. 3-Flat bones : They are composed of thin inner and outer layers e. g. Scapula ,ribs, and vault of the skull. 4-Irregular bones: They are irregular in shape having multiple processes e.g. vertebrae ,hip bone, and base of the skull 5-Sesamoid bone: They are small nodules of bone that are found in certain tendons. The greater sesamoid bone is patella. 6-Pneumatic bones: e.g. skull bones which contain air–filled spaces.  (B)Cartilage - Cartilage is a form of connective tissue in which the cells and fibres are embedded in a gel-like matrix - All these structures are covered with a fibrous membrane called perichondrium. (C ) Joints - A site where two or more bones come together whether or not movement occurs between them. - Classified according to the tissues that lie between the bones into: Fibrous joint Cartilaginous joint Synovial joints.  Fibrous joints The articulating surfaces of the bones are joined by fibrous tissue , and thus there is no movement. e.g. The sutures of the skull  Cartilaginous joints These joints have no or minimal movement ,and are joined by a layer of cartilage e.g. that between the first rib and the manubrium sterni, intervertebral joints.  Synovial joints The joint cavity is lined by a synovial membrane. The synovial membrane is protected on the outside by a fibrous membrane referred to as a capsule of the joint. Outside the capsule, there is a ligament ,which strengths it.