Musculoskeletal System. 2 Contents Introduction Functions of the skeleton Divisions of skeleton Axial skeleton Appendicular skeleton Bone structure Joints.

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3 Introduction This is a method of movement using muscles and bones in response to a stimulus.


Musculoskeletal System 2 Contents Introduction Functions of the skeleton Divisions of skeleton Axial skeleton Appendicular skeleton Bone structure Joints Synovial joints Movement Growth and development in bones Role of calcium in bone Disorders of the musculoskeletal system Arthritis Osteoporosis Other Musculoskeletal disorders 3 Introduction This is a method of movement using muscles and bones in response to a stimulus. 4 Functions of the skeleton Support - keeps the body upright and gives it shape. Protection - of delicate organs e.g. brain, lungs, heart and spinal cord. Movement - without the skeleton movement would be very slow e.g. earthworm. Long bones - manufacture red blood corpuscles, white blood cells and platelets. 5 Divisions of skeleton Axial skeleton, and Appendicular skeleton 6 The human skeleton 7 Axial skeleton (1/3) AXIAL SKELETON = skull + vertebral column + sternum + ribs. THE SKULL - composed of - the CRANIUM - protects brain and eyes, and gives shape to the head. - the JAWS - contain the teeth used in feeding. - attached to the top of the vertebral column. 8 Axial skeleton (2/3) THE VERTEBRAL COLUMN - composed of (33) vertebrae - cervical (7) - neck - thoracic (12) - ribs attached - lumbar (5) - small of back - sacral (5) - hips - caudal (4) tail 9 Parts of the vertebral column 10 Intervertebral discs Muscles and ligaments hold vertebrae together. Discs found between two vertebrae. Flexible and allow a little movement between each pair of vertebrae. Prevent bones rubbing off each other and act as shock absorbers. 11 Vertebrae diagram 12 Axial skeleton (3/3) THE STERNUM AND RIBS - ribs 1 to 7 attached to sternum - true ribs - ribs 8 to 10 attached to rib no. 7 - false ribs - ribs 11 & 12 - shorter with no attachments - floating ribs. Ribs protect the lungs and heart and used in breathing. 13 APPENDICULAR SKELETON APPENDICULAR SKELETON = all other bones - names should be known. pectoral girdle: the bones that attach the arms to the axial skeleton shoulder blades & colar bones. pelvic girdle: the fused bones of the hips, attached to the sacrum surrounding a cavity, that support the legs. 14 Axial & appendicular skeletons 15 Pentadactyl limbs arms and legs 16 Bone structure (1/2) Bones need to be of maximum strength and minimum weight in order to provide support and be moved by muscles. Compact bone strength and rigidity living cells needs blood and nerve supply. Spongy bone strength and rigidity contains bony bars and plates separated by irregular spaces spaces filled with 17 L.S. of a long bone 18 Red bone marrow produces blood cells Yellow bone marrow in centre of long bones (medullary cavity) stores fat. Cartilage - at ends of bones at a joint rubbery matrix may contain elastic protein fibres reduces friction between hard bones. Bone structure (2/2) 19 Joints (1/2) are where two bones meet. Three types of joints: - 1.Immovable bones held together without cartilage e.g. skull 20 Joints (2/2) 2.Slightly movable joints where flexibility is required e.g. vertebra in vertebral column. 3.Freely movable joints cartilage and a space at the joint called synovial joints four types 21 Synovial joints 1.BALL AND SOCKET JOINT e.g. shoulder, hip - allows circular movement. 2.HINGE JOINT e.g. elbow, knee - allows movement in one plane only. 3.GLIDING JOINT e.g. wrist, ankle - allows limited circular movement. 4.PIVOT JOINT e.g. in neck - skull rests on axis to allow head move from side to side and nod. 22 Synovial joints structure Synovial membrane surrounds joint and secretes synovial fluid lubricant Bones covered with cartilage Bones held together by ligaments LIGAMENTS - join bone to bone - elastic. TENDONS - join muscle to bone - non- elastic. 23 A synovial joint 24 Movement Muscles can only contract and relax (cannot expand or elongate). To contract they need energy - ATP, from respiration of glucose or glycogen with oxygen. 25 Antagonistic muscles (1/2) These are muscles working in pairs, opposing each other, controlling the movement of a joint. e.g. movement about the elbow controlled by biceps (= flexor muscle = bring bones closer to each other) and triceps (= extensor muscle = pull bones away from each other ). 26 Antagonistic muscles (2/2) To raise hand - biceps contract and triceps relax and is stretched by the upward movement of the radius and ulna. To lower hand - triceps contract and biceps relax and is stretched by the downward movement of the radius and ulna. 27 Bending at the elbow 28 Bending at the elbow 29 Growth and development in bones (1/2) Bone forming cells are called osteoblasts. These replace cartilage with bone during the growth stage in a human. The bone eventually stops increasing in size and limits the height of the individual. In adults bone is continually being broken down and replaced. As osteoclasts break bone down, osteoblasts build it up. 30 The conversion of an immature long bone from cartilage to bone 31 Growth and development in bones (2/2) osteoclast: a large cell, having more than one nucleus, that can break down and absorb calcified bone. The broken down bone is absorbed by osteoclasts. They remove worn cells and deposit calcium into the blood. The continued renewal of bone is dependent upon physical activity, hormone levels and diet. 32 Role of calcium in bone Bone contains a hard, rigid matrix comprised of a protein impregnated with a calcium salt and phosphorous The calcium gives strength to bones The protein gives flexibility and prevents the bone from being brittle 33 Disorders of the musculoskeletal system Study one of the following: - Arthritis OR Osteoporosis 34 Arthritis (1/2) arthritis: inflammation of a joint. There are many pathological (disease- related) causes, including bacterial or viral infection, inflammatory or degenerating disease, commonly rheumatoid arthritis and osteoarthritis. 35 Arthritis (2/2) Arthritis can affect different joints, and sufferers may have symptoms of pain, swelling over the joint and restricted movement. The treatment of arthritis depends on its cause if inflammatory, specific drugs help to relieve pain and swelling. Infection, anti-bacterial drugs and severe arthritis may require joint replacement. 36 Osteoporosis (1/2) osteoporosis: a reduction in the density of bones as result of the ageing process or from enforced inactivity = brittle bone disease. It is caused by excess reabsorption of bone and leads to an increased risk of fractures. Osteoporosis often follows the menopause, because oestrogen is responsible for maintaining bone calcium and levels of oestrogen fall after the menopause. 37 Osteoporosis (2/2) Osteoporosis may also be induced by long- term treatment with steroids, and may occur in males as well as females. Diagnosis is normally made using a DEXA scan (dual-energy X-ray absorptiometry). Damage can be limited by taking vitamin D and calcium tablets and by taking exercise e.g. walking. HRT can benefit some women. Other Musculoskeletal disorders not examinable for information only 39 Disc prolapse 40 Whiplash injury 41 Ligament injury 42 Torn cartilage 43 END


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