Presentation on theme: "The Musculoskeletal System"— Presentation transcript:
1 The Musculoskeletal System Chapter 27The Musculoskeletal System
2 Learning Objectives (1 of 2) Name common congenital abnormalities of the skeletal systemDescribe three major types of arthritis, pathogenesis, clinical manifestations, and treatmentDescribe causes and effects of osteoporosis, and methods of treatmentDescribe structure and functions of intervertebral disks; clinical manifestations of herniated disk
3 Learning Objectives (2 of 2) Describe pathogenesis, manifestations, and treatment of myasthenia gravisDescribe manifestations, complications, and treatment of scoliosisCompare pathogenesis, common types, and clinical manifestations of muscular atrophy and dystrophy
4 Skeletal System (1 of 2)Skeleton: rigid supporting structure of the bodyAll bones have same basic structureCortex: outer layer of compact bone, the cortexTrabeculae: inner spongy layer arranged in a loose meshed lattice of thin strandsBone marrow: spaces between trabeculae consist of fat and blood-forming tissueBone: specialized type of connective tissueComposed of a dense connective tissue framework impregnated with calcium phosphate saltsContinually broken down and reformed
5 Skeletal System (2 of 2) Types of cells in bone OsteoblastsOsteocytesOsteoclastsStrength and thickness of bones depend on activityBones of skeleton are connected by jointsTypes of jointsFibrous jointCartilaginous jointSynovial joint
6 Bone Formation Intramembranous Endochondral Mesoderm transformed into osteoblasts that are converted into boneEndochondralCartilage model converted into bone
7 Congenital Malformations (1 of 2) AchondroplasiaFaulty endochondral bone formationImpaired growth of extremities and formation of skull bonesCauses dwarfism with disproportionately short limbsOsteogenesis imperfectaThin and delicate bones easily brokenMay be born with multiple fracturesMalformation of fingers and toesExtra digits or polydactylyEasily removedFused digits more difficult to correct
8 Congenital Malformations (2 of 2) Congenital clubfoot (talipes)Multifactorial inheritanceMost common type: talipes equinavarusTreatment: manipulation and castsCongenital dislocation of the hipMore common in femalesShallow acetabulum causes femoral head to be displaced out of socketBreech position favors development
15 Rheumatoid Arthritis (RA) Systemic disease affecting connective tissues throughout the body, specially the jointsProduces chronic inflammation and thickening of synovial membraneClassified as an autoimmune diseaseRheumatoid factor: autoantibody in blood and synovial tissues; produced by B lymphocytes directed against individual’s own gamma globulinEncountered most frequently in young men and middle-aged womenUsually affects small joints of hands and feetDislocation from joint instability
18 Photomicrograph of rheumatoid arthritis illustrating destruction of articular cartilage by inflammatory reaction.
19 Photomicrograph of rheumatoid arthritis Photomicrograph of rheumatoid arthritis. Chronic inflammatory reaction in synovium.
20 Osteoarthritis Not a systemic disease “Wear and tear” degeneration of one or more weight-bearing jointsCauses degeneration of articular cartilageSeen in older adults, considered a manifestation of normal aging processTreatment: drugs; joint replacement if severe
21 Knee joint, illustrating smooth articular surface of femoral condyles.
24 Osteoporosis with a compression fracture of vertebral body.
25 Gout Disorder of purine metabolism Uric acid: an insoluble end-product of purine metabolismAcute episodes caused by precipitation of uric acid crystals in joint fluidUric acid stones also may form within kidney and lower urinary tractUrate nephropathy: urate deposits plug tubules and damage kidneysTreatment: diet and drugs that lower uric acid
27 Gout A. Mass of urate crystals with macrophages and fibrous tissue B Gout A. Mass of urate crystals with macrophages and fibrous tissue B. Needle-like sodium urate crystals under polarized light
28 Radiograph of right hand of patient with gouty arthritis illustrating area of bone destruction (arrow) caused by masses of uric acid crystals.
29 Fractures Simple fracture: bone broken in only two pieces Comminuted fracture: bone shattered into many piecesCompound fracture: overlying skin is broken with potential for infectionPathologic fracture: fracture through a diseased area in the boneTreatmentClosed reduction: plaster castOpen reduction: internal fixation
30 Osteomyelitis (1 of 2)Infection of bone and adjacent marrow cavity as a result of bacteriaOrganisms gain access to bone viaHematogenousBacteria carried to bone from an infection in body; occurs at ends of bonesSpread of infection may strip periosteum from cortex and devitalize boneMostly in childrenIn adults: infection may spread into jointsInfection in drug abusers tend to localize in vertebral bodies
31 Osteomyelitis (2 of 2)Organisms gain access to bone via direct implantation of bacteriaFrom conditions that expose bone to direct infectionFollowing trauma or surgeryManifestationFever, local pain and tendernessDiagnosis and treatmentX-ray reveals changes in boneAntibiotics, possible surgery
32 Tumors of the BoneUsually metastatic tumors from prostate, breasts, other organsMultiple myeloma: plasma cell neoplasmBenign cysts and tumors: encountered occasionallyPrimary malignant bone tumors: unusualChondrosarcoma: malignant tumor of cartilageOsteosarcoma: malignant tumor of bone-forming cells
33 A. Chondrosarcoma of chest wall B. Metastatic carcinoma in humerus
34 OsteoporosisGeneralized thinning and demineralization of entire skeletal system“Porous bones”Most common in postmenopausal womenLoss of estrogen accelerates rate of bone resorptionAlso develops in elderly menTreatment: high-calcium diet, estrogen
35 Osteoporosis, with compression fracture of vertebral body
36 Avascular NecrosisInterference in blood supply to the epiphysis of bonesResults in necrosis and degeneration at ends of boneDisturbance in blood supply probably from injuryLocal pain and disabilityCommon sitesFemoral head, tibial tubercle, articular surface of femoral condyle
39 Spine Vertebral column forms the central axis of the body Series of vertebrae joined by intervertebral disks and fibrous ligamentsDisks: fibrocartilaginous cushions interposed between adjacent vertebral bodies; function as shock absorbers4 curves of vertebral columnCervical and lumbar curves arch forwardThoracic and sacral curves bend in opposite direction
40 A. Side view of vertebral column illustrating normal curves. B A. Side view of vertebral column illustrating normal curves. B. Structure of typical vertebra viewed from above. C. Side view of two vertebrae.
41 Cross-section through the lumbar spine at the level of the intervertebral disk.
42 Intervertebral Disk Disease Intervertebral disks undergo progressive wear-and-tear degeneration of both nucleus and annulusNucleus pulposus may be extruded through tear in annulus fibrosusManifestationSudden onset of back pain radiating down the legDiagnosis: CT scan or myelogramTreatment: surgery
43 Herniated nucleus pulposus (“slipped disk”) Herniated nucleus pulposus (“slipped disk”). Schematic of anatomic structures and lesion as demonstrated on CT scan.
44 Herniated nucleus pulposus (“slipped disk”) Herniated nucleus pulposus (“slipped disk”). X-ray examination obtained after radiopaque contrast material was instilled into dural sac.
46 Scoliosis Abnormal lateral curvature of spine Occurs in 4% of the populationMost cases are idiopathic, occurs in adolescenceCan lead to asymmetry of trunk and ↓size of thoracic cavityOne shoulder is higher than the other; pelvis is tiltedLarge curvatures cause pronounced disabilitiesTreatment: depends on extent of curvature
48 Skeletal Muscle (1 of 3) Muscle contraction Myofilaments slide togetherMyoneural junction: communication between nerve and muscleNerve stimulation releases acetylcholine that interacts with receptors on surface of muscle fibers andinitiates contractionNormal structural and functional integrity depends onIntact nerve supplyNormal transmission of impulses across myoneural junctionNormal metabolic processes within muscle cell
49 Skeletal Muscle (2 of 3) Myositis: muscle inflammation LocalizedFrom injury or overexertionGeneralizedSystemic diseaseWidespread degeneration and inflammation of skeletal muscle or polymyositisDermatomyositis: type of polymyositis associated with swelling and inflammation of skin
50 Skeletal Muscle (3 of 3)Group of relatively rare diseases characterized by progressive atrophy or degeneration of skeletal muscleCategoriesProgressive muscular atrophySecondary to motor nerve cell degeneration with secondary muscle atrophyMuscular dystrophyPrimary muscle degeneration
51 Myasthenia GravisChronic disease characterized by abnormal fatigability of voluntary muscles due to abnormality at the myoneural junctionAutoimmune disease; autoantibodies against acetylcholine receptors at myoneural junctionTreatment: drugs that prolong action of acetylcholine
52 DiscussionArthritis pain that begins in one joint is usually characteristic of:A. Rheumatoid arthritisB. OsteoarthritisJoint pain accompanied by redness, swelling, warmth, and tenderness is usually characteristic of:Type of arthritis that affects only joints and not internal organs.