Download - Structure and Function of the Musculoskeletal System Chapter 41 Mosby items and derived items © 2010, 2006 by Mosby, Inc., an affiliate of Elsevier Inc.

Structure and Function of the Structure and Function of the Musculoskeletal SystemMusculoskeletal System

Chapter 41Chapter 41

Mosby items and derived items © 2010, 2006 by Mosby, Inc., an affiliate of Elsevier Inc.Mosby items and derived items © 2010, 2006 by Mosby, Inc., an affiliate of Elsevier Inc.

22Mosby items and derived items © 2010, 2006 by Mosby, Inc., an affiliate of Elsevier Inc.Mosby items and derived items © 2010, 2006 by Mosby, Inc., an affiliate of Elsevier Inc.

Skeletal SystemSkeletal System Forms the bodyForms the body Supports tissues Supports tissues Permits movement by providing points of Permits movement by providing points of

attachment for musclesattachment for muscles Site of blood cell formationSite of blood cell formation Mineral storageMineral storage


BoneBone Rigid yet flexible connective tissueRigid yet flexible connective tissue ConstituentsConstituents

CellsCells FibersFibers Ground substanceGround substance


Bone TissueBone Tissue OsteoblastsOsteoblasts

Derived from mesenchymal cellsDerived from mesenchymal cells Produce type I collagenProduce type I collagen Respond to parathyroid hormoneRespond to parathyroid hormone Produce osteocalcin Produce osteocalcin Synthesize osteoidSynthesize osteoid

• Nonmineralized bone matrixNonmineralized bone matrix


Bone TissueBone Tissue

OsteocyteOsteocyte Transformed osteoblast surrounded in osteoid as it Transformed osteoblast surrounded in osteoid as it

hardens from deposited mineralshardens from deposited minerals OsteoclastOsteoclast

The major reabsorptive cell of the boneThe major reabsorptive cell of the bone Large, multinucleated cellsLarge, multinucleated cells Contains lysosomes filled with hydrolytic enzymesContains lysosomes filled with hydrolytic enzymes


Bone MatrixBone Matrix 35% organic and 65% inorganic35% organic and 65% inorganic Collagen fibers Collagen fibers Calcium and phosphate mineralsCalcium and phosphate minerals ProteoglycansProteoglycans GlycoproteinsGlycoproteins


Bone TissueBone Tissue Compact (cortical) boneCompact (cortical) bone

85% of the skeleton85% of the skeleton Haversian systemHaversian system

• Haversian canal, lamellae, lucunae, osteocyte, and Haversian canal, lamellae, lucunae, osteocyte, and canaliculicanaliculi

Spongy (cancellous) boneSpongy (cancellous) bone Lack haversian systemsLack haversian systems TrabeculaeTrabeculae

PeriosteumPeriosteum


Compact BoneCompact Bone


BoneBone 206 bones206 bones Axial skeletonAxial skeleton

80 bones 80 bones • Skull, vertebral column, thoraxSkull, vertebral column, thorax

Appendicular skeletonAppendicular skeleton 126 bones 126 bones

• Upper and lower extremities, the shoulder girdle, the Upper and lower extremities, the shoulder girdle, the pelvic girdlepelvic girdle


SkeletonSkeleton


BonesBones

Long bonesLong bones DiaphysisDiaphysis MetaphysisMetaphysis EpiphysisEpiphysis

• Epiphyseal plateEpiphyseal plate In a child epiphysis is separated from metaphysis by a In a child epiphysis is separated from metaphysis by a

cartilaginous growth plate. After puberty epiphyseal plate cartilaginous growth plate. After puberty epiphyseal plate calcifies and epiphysis and metaphysis merge calcifies and epiphysis and metaphysis merge

• Epiphyseal lineEpiphyseal line

Medullary cavityMedullary cavity EndosteumEndosteum


Long BoneLong Bone


BonesBones Flat bonesFlat bones Short bones (cuboidal bones)Short bones (cuboidal bones) Irregular bonesIrregular bones


Bone RemodelingBone Remodeling Bone-remodeling unitsBone-remodeling units Repairs microscopic injuries and maintains Repairs microscopic injuries and maintains

bone integritybone integrity PhasesPhases

Activation of the remodeling cycleActivation of the remodeling cycle Reabsorption Reabsorption Formation of new boneFormation of new bone


Bone RemodelingBone Remodeling


Bone Wound HealingBone Wound Healing Hematoma formationHematoma formation Procallus formationProcallus formation Callus formationCallus formation Callus replacementCallus replacement RemodelingRemodeling


JointsJoints Site where two or more bones meetSite where two or more bones meet Promote stability and mobility of the skeletonPromote stability and mobility of the skeleton


JointsJoints Joint classifications based on movementJoint classifications based on movement

SynarthrosisSynarthrosis• ImmovableImmovable

AmphiarthrosisAmphiarthrosis• Slightly movableSlightly movable

Diarthrosis Diarthrosis • Freely movableFreely movable


JointsJoints Joint classifications based on structureJoint classifications based on structure FibrousFibrous

Usually synarthroses (immovable)Usually synarthroses (immovable) However, many allow some movementHowever, many allow some movement

• Degree of movement depends on the distance between Degree of movement depends on the distance between the bones and the flexibility of the fibrous connective the bones and the flexibility of the fibrous connective tissuetissue

Sutures, syndesmoses, and gomphoses Sutures, syndesmoses, and gomphoses


JointsJoints Joint classifications based on structureJoint classifications based on structure CartilaginousCartilaginous

• SymphysisSymphysis Bones are united by a pad or disk of fibrocartilage Bones are united by a pad or disk of fibrocartilage Example: symphysis pubis, intervetebral disksExample: symphysis pubis, intervetebral disks

• SynchondrosisSynchondrosis Bones are united by hyaline cartilage Bones are united by hyaline cartilage Example: joints between the ribs and the sternumExample: joints between the ribs and the sternum


JointsJoints

Classifications based on structureClassifications based on structure Synovial (most movable, most complex) contain:Synovial (most movable, most complex) contain:

A fibrous joint capsule (articular capsule)A fibrous joint capsule (articular capsule) Synovial membrane that lines inner surface of joint Synovial membrane that lines inner surface of joint

capsulecapsule Joint cavity (synovial cavity), a space formed by the Joint cavity (synovial cavity), a space formed by the

capsulecapsule Synovial fluid, which fills the joint cavity and lubricates Synovial fluid, which fills the joint cavity and lubricates

joint surfacejoint surface Articular cartilage, which covers and pads the Articular cartilage, which covers and pads the

articulating bony surfacesarticulating bony surfaces


JointsJoints


Skeletal MusclesSkeletal Muscles Millions of individual muscle fibers that Millions of individual muscle fibers that

contract and relax to facilitate movementcontract and relax to facilitate movement 75% water, 20% protein, 5% organic and 75% water, 20% protein, 5% organic and

inorganic compoundsinorganic compounds 350 named muscles (most are paired)350 named muscles (most are paired) 2 to 60 cm long2 to 60 cm long Fusiform musclesFusiform muscles Pennate musclesPennate muscles


Skeletal MusclesSkeletal Muscles


Skeletal MusclesSkeletal Muscles Whole muscleWhole muscle

FasciaFascia EpimysiumEpimysium TendonTendon PerimysiumPerimysium FasciclesFascicles EndomysiumEndomysium


MuscleMuscle Skeletal muscleSkeletal muscle

Voluntary Voluntary • Controlled directly by the central nervous systemControlled directly by the central nervous system

StriatedStriated• The striated, or striped, pattern of skeletal muscle The striated, or striped, pattern of skeletal muscle • Result from organization of muscle fibers into the contractile Result from organization of muscle fibers into the contractile

units called units called sarcomeressarcomeres Extrafusal Extrafusal

• Distinguishes skeletal muscle fibers from other contractile Distinguishes skeletal muscle fibers from other contractile fibersfibers


MuscleMuscle Motor unit (anterior horn cell, its axon, and its Motor unit (anterior horn cell, its axon, and its

muscle fiber)muscle fiber) Anterior horn cell of the spinal cordAnterior horn cell of the spinal cord Axons of motor nerves branch out to innervate a Axons of motor nerves branch out to innervate a

specific group of muscle fibers; lower motor specific group of muscle fibers; lower motor neuronsneurons

Functional unit of the neuromuscular systemFunctional unit of the neuromuscular system Innervation ratioInnervation ratio Sensory receptorsSensory receptors


Motor UnitsMotor Units


MuscleMuscle Innervation ratioInnervation ratio

Motor units per muscleMotor units per muscle The greater the innervation ratio of a particular The greater the innervation ratio of a particular

organ, the greater its enduranceorgan, the greater its endurance Higher innervation ratios prevent fatigueHigher innervation ratios prevent fatigue Lower innervation ratios allow for precision of Lower innervation ratios allow for precision of

movementmovement


MuscleMuscle

Sensory receptors (send signals to the central Sensory receptors (send signals to the central nervous system)nervous system) SpindlesSpindles

• Mechanoreceptors that lie parallel to muscle fibersMechanoreceptors that lie parallel to muscle fibers

• Respond to muscle stretchingRespond to muscle stretching

Golgi tendon organs: dendrites that terminate and Golgi tendon organs: dendrites that terminate and branch to tendons near the neuromuscular junctionbranch to tendons near the neuromuscular junction

Spindles, Golgi tendon organs, and free nerve Spindles, Golgi tendon organs, and free nerve endings report changes in muscle length, tension, endings report changes in muscle length, tension, velocityvelocity

System of afferent signals responsible for muscle System of afferent signals responsible for muscle stretch response and maintaining muscle tonestretch response and maintaining muscle tone


Muscle FibersMuscle Fibers MyofibrilsMyofibrils Myoblasts Myoblasts White muscle (type II fibers)White muscle (type II fibers) Red muscle (type I fibers)Red muscle (type I fibers) Muscle membraneMuscle membrane

Sarcolemma and basement membraneSarcolemma and basement membrane SarcoplasmSarcoplasm


Muscle FibersMuscle Fibers Sarcotubular systemSarcotubular system

Transverse tubules Transverse tubules Sarcoplasmic reticulumSarcoplasmic reticulum

SarcomereSarcomere Actin Actin MyosinMyosin Troponin-tropomyosin complexTroponin-tropomyosin complex


MyofibrilsMyofibrils


Muscle FibersMuscle Fibers Creatine and creatine kinaseCreatine and creatine kinase Phosphate, chloride, calcium, magnesium, Phosphate, chloride, calcium, magnesium,

sodium, potassiumsodium, potassium


Muscle ContractionMuscle Contraction ActivationActivation

Muscle fiber action potentialMuscle fiber action potential CouplingCoupling ContractionContraction

Cross-bridge theoryCross-bridge theory RelaxationRelaxation


Muscle Contractions and Muscle Contractions and MovementMovement

Types of contractionsTypes of contractions IsometricIsometric IsotonicIsotonic

• EccentricEccentric

• Concentric Concentric

Muscle movementMuscle movement AgonistAgonist AntagonistAntagonist


Test of Bone FunctionTest of Bone Function Gait analysisGait analysis Serum calcium and phosphorusSerum calcium and phosphorus X-raysX-rays AngiographyAngiography Bone scanningBone scanning


Test of Joint FunctionTest of Joint Function ArthrographyArthrography ArthroscopyArthroscopy MRIMRI Synovial fluid analysisSynovial fluid analysis


Test of Muscular FunctionTest of Muscular Function Serum creatine kinase Serum creatine kinase MyoglobinMyoglobin EMGEMG


Aging and the Aging and the Musculoskeletal SystemMusculoskeletal System

BonesBones Bone lossBone loss Stiff, brittle, decreased strengthStiff, brittle, decreased strength Bone remodel time is lengthenedBone remodel time is lengthened

JointsJoints Cartilage becomes more rigid, fragile, stiffCartilage becomes more rigid, fragile, stiff Decreased range of motionDecreased range of motion


Aging and the Aging and the Musculoskeletal SystemMusculoskeletal System

MusclesMuscles SarcopeniaSarcopenia Decrease in muscle strength and bulkDecrease in muscle strength and bulk Reduced oxygen intake, basal metabolic rate, and Reduced oxygen intake, basal metabolic rate, and

lean body masslean body mass