Bones, Joints and Muscles

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Bones, Joints and Muscles. Bones: 206 in human body. Function: support (eg) pelvic bowl, legs protect (eg) skull, vertebrae mineral storage (eg) calcium, phosphate, inorganic component movement (eg) walk, grasp objects blood-cell formation (eg) red bone marrow - PowerPoint PPT Presentation


  • Bones, Joints and Muscles

  • Bones: 206 in human body Function:support (eg) pelvic bowl, legsprotect (eg) skull, vertebraemineral storage (eg) calcium, phosphate, inorganic componentmovement (eg) walk, grasp objectsblood-cell formation (eg) red bone marrowOsteoblasts: secrete organic part of bone matrix = osteoidOsteocytes: mature bone cells, maintain bone matrix

  • Some Reminders about BonesBone = bone tissue (type of CT)A Bone = an organCompact vs. Spongy BoneComposition: Hydroxyapatite, protoplasm, collagen, blood vessels, marrowSkeleton = bones, cartilage (avascular, no nerves, 80% H2O), joints, ligamentsShapes of BonesLong, Flat, Irregular, ShortBefore 8 weeks, embryo is all cartilage

  • Structure of Bone

  • Anatomy of a Long BoneDiaphysisMedullary CavityNutrient Art & Vein2 EpiphysesEpiphyseal PlatesEpiphyseal Art & VeinPeriosteumOuter: Dense irregular CTInner: Osteoblasts, osteoclastsDoes not cover epiphysesAttaches to bone matrix via collagen fibersEndosteumOsteoblasts, osteoclastsCovers trabeculae, lines medullary cavity

  • 2 Types of Bone Formation1) Intramembranous OssificationMembrane bones: most skull bones and clavicleOsteoblasts in membrane secrete osteoid that mineralizesOsteocytes maintain new bone tissueTrabeculae forms between blood vesselsGrows into thickened plates at periphery = compact bonePeriosteum forms over it

  • 2 Types of Bone Formation :2) Endochondral Ossification: All other bones Begins with a cartilaginous model Perichondrium becomes replaced by periosteumCartilage in diaphysis calcifies Trabeculae forms from Periosteal budPeriosteal bud = arteries & veins, cells forming bone marrow, osteoblasts, osteoclastsMedullary cavity is formed by action of osteoclastsEpiphyses grow and eventually calcifyEpiphyseal plates remain cartilage for up to 20 years

  • Bone Growth & RemodelingGROWTHAppositional Growth = widening of boneBone tissue added on surface by osteoblasts of periosteumMedullary cavity maintained by osteoclastsLengthening of BoneEpiphyseal plates enlarge by chondroblasts Matrix calcifies (chondrocytes die and disintegrate)Bone tissue replaces cartilage on diaphysis sideREMODELINGDue to mechanical stresses on bones, their tissue needs to be replacedOsteoclasts-take up bone ( = breakdown) release Ca2++ , PO4 to body fluids from boneOsteoblasts-lay down bonesecrete osteoid to form new boneIdeally osteoclasts and osteoblasts work at the same rate!

  • Joints (articulations) Where parts of skeleton meetAllows varying amounts of mobilityClassified by structure or functionArthrology: study of joints

  • Classification of Joints

    Function:Synarthroses = no/little movementAmphiarthroses = slight movementDiarthroses = great movement

  • Joints by Functional Classification

    TypeMovementExampleSynarthrosisNone (minimal)Sutures, Teeth,Epiphyseal plates,1st rib and costal cart.AmphiarthrosisSlightDistal Tibia/fibulaIntervertebral discsPubic symphysisDiarthrosisGreatGlenohumeral jointKnee jointTMJ

  • Joint ClassificationStructureCartilagenousSynchondrosis: connected by hyaline cartilage (synarthroses)Symphysis: connected by fibrocartilage (amphiarthroses)FibrousSutures: connected by short strands of dense CT (synarthroses)Syndesmoses: connected by ligaments (varies)Gomphosis: peg in socket w/short ligament (synarthroses)Synovial (diarthroses)

  • Joints by Structural Classification

    StructureTypeExampleCartilagenousSynchondrosisSymphysisEpiphyseal platesIntervertebral discsFibrousSuturesSyndesmosesGomphosisSkullDistal Tibia/fibulaTeeth in socketsSynovialGlenohumeral jointKnee jointTMJ

  • Components of SYNOVIAL JOINTS:(Structural Joint Classification continued)Articular cartilage: hyaline; covers ends of both bones articulatingSynovial (joint) cavity: space holding synovial fluidArticular capsule: Made of 2 layersFibrous: external, dense CT for strengthSynovial membrane: internal, produces synovial fluidSynovial fluid: viscous; lubricates and nourishes; contained in capsule and articular cartilagesReinforcing ligaments: extracapsular/intracapsularNerves + vessels: Highly innervated, Highly vascularMeniscus (some): fibrocartilage; improves the fit of 2 bones to increase stability

  • Synovial Jointpg 215

  • Bursae & Tendon SheathsBursae: flat, fibrous sac w/synovial membrane liningTendon Sheaths: elongated bursae that wraps around tendons3 Factors in Joint Stability:Muscle Tone Ligaments Fit of Articular Surfacepg 219

  • Joint ShapesHinge: cylindrical end of 1 bone fits into trough shape of otherangular movement-1 plane (eg) elbow, ankle, interphalangal

    Plane: articular surface in flat planeShort gliding movement(eg) intertarsal, articular processes of vertebraepg 224

  • Joint ShapesCondyloid: egg-shape articular surface + oval concavityside-to-side, back+forth movement(eg) metacarpophalangeal (knuckle)

    Pivot: round end fits into ring of bone + ligamentrotation on long axis(eg) prox. radius/ulna, atlas/denspg 225

  • Joint ShapesSaddle: articular surface both concave + convexside-to-side, back-forth movement(eg) carpometacarpal jt of thumb Ball + Socket: spherical head + round socketmultiaxial movement(eg) shoulder, femurpg 225

  • !Muscles!Function: 1) movement 2) maintain posture 3) joint stability 4) generate heat!Muscles!

  • Special Features of MuscleContractibility = cells generate pulling forceExcitibility = nervous impulses travel through muscle plasma membrane to stimulate contractionExtensibility = after contraction muscle can be stretched back to original length by opposing muscle actionElasticity = after being stretched, muscle passively recoils to resume its resting length

  • Muscle System: uses levers to move objectsHow it works: A rigid bar moves on fixed point when a force is applied to it, to move objectLever = rigid bar = boneFulcrum = fixed point = jointEffort = force applied = muscle contractionLoad = object being moved = bone

  • Movements of Muscles

    Extension: increasing angle between body parts Flexion: decreasing angle between body parts Dorsiflexion vs. PlantarflexionInversion vs. EversionAbduction: moving away from the median planeAdduction: moving towards the median planeRotation: moving around the long axisCircumduction: moving around in circles

  • Movements of MusclesElevation: lifting body part superiorlyDepression: moving body part inferiorlySupination: rotating forearm laterallyPronation: rotating forearm mediallyProtraction: Anterior movement Retraction: Posterior movement

  • Muscle Basics to Remember3 Types: Skeletal, Cardiac, SmoothOrigin vs. InsertionDirect vs. Indirect Attachmentsdirect = right onto boneindirect = via tendon/aponeurosis more commonleave bony markings = tubercle, crest, ridge, etc.Sometimes attach to skin

  • Functional Muscle GroupsAgonist = primary mover of a muscle, major response produces particular movement(eg) biceps brachii is main flexor of forearm

    Antagonists = oppose/reverse particular movement, prevent overshooting agonistic motion(eg) triceps brachii is antagonist to biceps brachii

  • Functional Muscle GroupsSynergists = muscles work together, adds extra force to agonistic movement, reduce undesirable extra movement (eg) muscles crossing 2 joints

    Fixators = a synergist that holds bone in place to provide stable base for movement (eg) joint stablilizers

  • Naming MusclesLocation: (eg) brachialis = armShape: (eg) deltoid = triangleRelative Size: (eg) minimus, maximus, longusDirection of Fascicles: (eg) oblique, rectusLocation of Attachment: (eg) brachioradialisNumber of Origins: (eg) biceps, quadricepsAction: (eg) flexor, adductor, extensor

  • Arrangement of Muscle FibersParallel: long axis of fascicles parallel to axis of muscle; straplike (eg) biceps, sternocleidomastoid

    Convergent: O = broad, I = narrow, via tendon; fan or triangle shaped (eg) pectoralis major

    Circular: fascicles arranged in concentric circles; sphincter (eg) around mouth

  • Arrangement of Muscle FibersPennate: fascicles short + attached obliquely to tendon running length of muscle; featherlikeUnipennate = fascicles insert on only 1 side (eg) flexor pollicis longusBipennate = fascicles insert both sides (eg) rectus femorisMultipennate = many bundles inserting together(eg) deltoid

  • Arrangements of Muscle Fasciclespg 269

  • STOPMore on Levers on the following pages

  • First Class LeverEffort at 1 endLoad at other endFulcrum in middle(eg) scissors(eg) moving head up and downpg 267

  • Second Class LeverEffort at 1 endFulcrum at other endLoad in middle(eg) wheelbarrel(eg) standing on tip toes (not common in body)pg 267

  • Third Class LeverLoad at 1 endFulcrum at other endForce in middle(eg) using a tweezers(eg) lifting w/bicepspg 267

  • Mechanical AdvantageWhen the load is close to the fulcrum, effort is applied far from fulcrumSmall effort over large distance = move large load over short distance(eg) Using a jack on a carpg 266

  • Mechanical DisadvantageWhen the load is farther from the fulcrum than the effort, the effort applied must be greater than the load being movedLoad moved quickly over large distance (eg) using a shovelpg 266


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