1 Structure and Function of the Musculoskeletal System Chapter 41

Mosby items and derived items © 2006 by Mosby, Inc. 2 Skeletal System  Forms the body  Supports tissues  Permits movement by providing points of attachment for muscles  Site of blood cell formation  Mineral storage

Mosby items and derived items © 2006 by Mosby, Inc. 3 Bone  Rigid connective tissue  Constituents Cells Fibers Ground substance

Mosby items and derived items © 2006 by Mosby, Inc. 4 Bone Tissue  Osteoblasts Derived from mesenchymal cells Produce type I collagen Respond to parathyroid hormone Produce osteocalcin Synthesize osteoid  Nonmineralized bone matrix

Mosby items and derived items © 2006 by Mosby, Inc. 5 Bone Tissue  Osteocytes A transformed osteoblast that is surrounded in osteoid as it hardens from deposited minerals  Osteoclast The major reabsorptive cell of the bone Large, multinucleated cells Contain lysosomes filled with hydrolytic enzymes

Mosby items and derived items © 2006 by Mosby, Inc. 6 Bone Matrix  35% organic and 65% inorganic  Collagen fibers  Calcium and phosphate minerals  Proteoglycans  Glycoproteins

Mosby items and derived items © 2006 by Mosby, Inc. 7 Bone Tissue  Compact (cortical) bone 85% of the skeleton Haversian system  Haversian canal, lamellae, lucunae, osteocyte, and canaliculi  Spongy (cancellous) bone Lack haversian systems Trabeculae  Periosteum

Mosby items and derived items © 2006 by Mosby, Inc. 8 Compact Bone

Mosby items and derived items © 2006 by Mosby, Inc. 9 Bone  206 bones  Axial skeleton 80 bones  Skull, vertebral column, thorax  Appendicular skeleton 126 bones  Upper and lower extremities, the shoulder girdle, the pelvic girdle

Mosby items and derived items © 2006 by Mosby, Inc. 10 Skeleton

Mosby items and derived items © 2006 by Mosby, Inc. 11 Bones  Long bones Diaphysis Metaphysis Epiphysis  Epiphyseal plate  Epiphyseal line Medullary cavity Endosteum

Mosby items and derived items © 2006 by Mosby, Inc. 12 Long Bone

Mosby items and derived items © 2006 by Mosby, Inc. 13 Bones  Flat bones  Short bones (cuboidal bones)  Irregular bones

Mosby items and derived items © 2006 by Mosby, Inc. 14 Bone Remodeling  Bone-remodeling units  Repairs microscopic injuries and maintains bone integrity  Phases Activation of the remodeling cycle Reabsorption Formation of new bone

Mosby items and derived items © 2006 by Mosby, Inc. 15 Bone Remodeling

Mosby items and derived items © 2006 by Mosby, Inc. 16 Bone Wound Healing  Hematoma formation  Procallus formation  Callus formation  Callus replacement  Remodeling

Mosby items and derived items © 2006 by Mosby, Inc. 17 Joints  Site where two or more bones meet  Promote stability and mobility to the skeleton

Mosby items and derived items © 2006 by Mosby, Inc. 18 Joints  Joint classifications based on movement Synarthrosis Amphiarthrosis Diarthrosis

Mosby items and derived items © 2006 by Mosby, Inc. 19 Joints  Joint classifications based on structure Fibrous  Suture, syndesmosis, gomphosis Cartilaginous  Symphysis and synchondrosis Synovial  Joint capsule, synovial membrane, joint cavity, synovial fluid, articular cartilage

Mosby items and derived items © 2006 by Mosby, Inc. 20 Joints

Mosby items and derived items © 2006 by Mosby, Inc. 21 Joints

Mosby items and derived items © 2006 by Mosby, Inc. 22 Joints

Mosby items and derived items © 2006 by Mosby, Inc. 23 Joints

Mosby items and derived items © 2006 by Mosby, Inc. 24 Joints

Mosby items and derived items © 2006 by Mosby, Inc. 25 Skeletal Muscles  Millions of individual muscle fibers that contract and relax to facilitate movement  75% water, 20% protein, 5% organic and inorganic compounds  350 named muscles (most are paired)  2 to 60 cm long  Fusiform muscles  Pennate muscles

Mosby items and derived items © 2006 by Mosby, Inc. 26 Skeletal Muscles

Mosby items and derived items © 2006 by Mosby, Inc. 27 Skeletal Muscles

Mosby items and derived items © 2006 by Mosby, Inc. 28 Skeletal Muscles  Whole muscle Fascia Epimysium Tendon Perimysium Fascicles Endomysium

Mosby items and derived items © 2006 by Mosby, Inc. 29 Skeletal Muscle

Mosby items and derived items © 2006 by Mosby, Inc. 30 Muscle  Skeletal muscle Voluntary Striated  Sarcomeres Motor unit  Lower motor neurons  Innervation ratios Sensory receptors

Mosby items and derived items © 2006 by Mosby, Inc. 31 Motor Units

Mosby items and derived items © 2006 by Mosby, Inc. 32 Muscle Fibers  Myofibrils  Myoblasts  White muscle (type II fibers)  Red muscle (type I fibers)  Muscle membrane Sarcolemma and basement membrane  Sarcoplasm

Mosby items and derived items © 2006 by Mosby, Inc. 33 Muscle Fibers  Sarcotubular system Transverse tubules Sarcoplasmic reticulum  Sarcomere Actin Myosin Troponin-tropomyosin complex

Mosby items and derived items © 2006 by Mosby, Inc. 34 Myofibrils

Mosby items and derived items © 2006 by Mosby, Inc. 35 Myofibrils

Mosby items and derived items © 2006 by Mosby, Inc. 36 Muscle Fibers  Creatine and creatine kinase  Phosphate, chloride, calcium, magnesium, sodium, potassium

Mosby items and derived items © 2006 by Mosby, Inc. 37 Muscle Contraction  Activation Muscle fiber action potential  Coupling  Contraction Cross-bridge theory  Relaxation

Mosby items and derived items © 2006 by Mosby, Inc. 38 Muscle Contractions and Movement  Types of muscle contractions Isometric contraction Isotonic contraction  Eccentric  Concentric  Muscle movement Agonist Antagonist

Mosby items and derived items © 2006 by Mosby, Inc. 39 Test of Bone Function  Gait analysis  Serum calcium and phosphorus  X-rays  Angiography  Bone scanning

Mosby items and derived items © 2006 by Mosby, Inc. 40 Test of Joint Function  Arthrography  Arthroscopy  MRI  Synovial fluid analysis

Mosby items and derived items © 2006 by Mosby, Inc. 41 Test of Muscular Function  Serum creatine kinase  Myoglobin  EMG

Mosby items and derived items © 2006 by Mosby, Inc. 42 Aging and the Musculoskeletal System  Bones Bone loss Stiff, brittle, decreased strength Bone remodel time is lengthened  Joints Cartilage becomes more rigid, fragile, stiff Decreased range of motion

Mosby items and derived items © 2006 by Mosby, Inc. 43 Aging and the Musculoskeletal System  Muscles Sarcopenia Decrease in muscle strength and bulk Reduced oxygen intake, basal metabolic rate, and lean body mass