ARTICULATIONS

HumanAnatomyUnit1

InAnatomyToday

ClassificationofJoints• Criteria– Howbonesarejoinedtogether– Degreeofmobility

• Minimumcomponents– 2articulatingbones– Interveningtissue

• FibrousCTorcartilage

• Categories– Synarthroses– nomovement– Amphiarthrosis– slightmovement– Diarthrosis– freelymovable

Synarthrosis

• Immovablearticulation• Types– Sutures– Schindylesis– Gomphosis– Synchondrosis

SynarthrosisSutures

• Foundonlyinskull• Immovablearticulation• FlatbonesjoinedbythinlayeroffibrousCT• Types– Serrate– Squamous(lap)– Plane

SynarthrosisSutures

• Serrate• Serratededgesofboneinterlock

• Twoportionsoffrontalbones

• Squamous(lap)• Overlappingbeveledmarginsformssmoothline

• Temporalandparietalbones

• Plane• Jointformedbystraight,nonoverlappingedges

• Palatineprocessofmaxillae

SynarthrosisSchindylesis

• Immovablearticulation• Thinplateofboneintocleftorfissureinaseparationofthelaminaeinanotherbone

• Articulationofsphenoidboneandperpendicularplateofethmoidbonewithvomer

SynarthrosisGomphosis

• Immovablearticulation• Conicalprocessintoasocket

• Articulationofteethwithalveoliofmaxillarybone

• Periodontalligament=fibrousCT

SynarthrosisSynchondrosis

• Cartilagenousjoints– Ribsjoinedtosternumbyhyalinecartilage

• Synostoses– Whenjointossifies– Epiphysealplatebecomesepiphysealline

Amphiarthrosis

• Slightlymoveablearticulation• Articulatingbonesconnectedinoneoftwoways:– Bybroadflattenedfibro-cartilagediscs• Fibrocartilage• Symphisis

– Byinterosseusligaments• Syndesmosis

AmphiarthrosisSymphysis

AmphiarthrosisSyndesmosis

• Twobonesjoinedbyinterosseousmembrane

• Example– Radioulnarjoint– Tibulofibularjoint

Diarthrosis

• Synovialjoints• Freelymovable• Types– Hinge– Gliding– Pivot– Saddle– Condyloid– Ballandsocket

SynovialJointStructure

GeneralAnatomy• Articularcartilage

– Hyalinecartilage– Coversendsofbones

• Jointcapsule– Enclosesjointcavity– Retainssynovialfluid– Twoparts

• Fibrouscapsule• Synovialmembrane

• Synovialfluid– Producedbyfibroblasts– Lubricatesjoint– Nourishesarticularcartilage– Removeswaste– Containsalbuminandhyaluronic

acid

GeneralAnatomy

• Meniscus– Cartilagesthatdonotcross

joint– Foundinknee– Shockabsorbers– Guidemovementofbone– Stabilizejoint

• AccessoryStructures– Tendon– Ligaments– Bursae(pl.)

• Fibroussacfilledwithsynovialfluid

TemperomandibularJoint

• Articulardisc– Fibrocartilagepad

crossesjointcapsule– Foundin

temporomadibularandradioulnarjoints

DiarthrosesHingeJoints

• Monaxial• Articulationbetweenconcaveandconvexsurfaces

• Locations– Knee– Elbow– Betweenphalanges

DiarthrosesGlidingJoints

• Biaxial• Articularsurfacesflatorslightlyconcaveandconvex

• Sidetosideorback/forthmotionwithslightrotation

• Locations– Betweencarpals– Betweentarsals

DiarthrosesPivotJoints

• Monaxial• Conicalbonefitsintoadepression

• Rotationaroundacentralaxis

• Locations– Radius/ulna– Atlas/axis

DiarthrosesSaddleJoints

• Eacharticularprocessisconcaveinonedirection,convexinanother

• Amodifiedcondyloidarticulationwithawiderrangeofmovement

• Locations– Betweenthetrapeziumand

1stmetacarpal– Betweenthemalleusand

incus

DiarthrosesCondyloidJoints

• Biaxial• Convexsurfaceisovalshaped

• Up/down,sidetosidemovements

• Locations– Radius/carpals– Metacarpals/phalanges

DiarthrosesBallandSocketJoints

• Multiaxial• Greatestrangeofmovementofallsynovialjoints

• Roundedconvexsurfacewithacuplikecavity

• Locations– Shoulder– Hip

MovementsofSynovialJointsMovementTerminology

• Flexion,Extension,andHyperextension• Abductionandadduction• Elevationanddepression• Protractionandretraction• Lateralandmedialexcursion• Circumduction• Rotation• Supinationandpronation• Oppositionandreposition• Dorsiflexionandplantarflexion• Inversionandeversion

Flexion,Extension,andHyperextension

• Flexion– Decreaseintheangleofthejoint– Usuallyinasagittalplane– Ex)bendingtheelbow

• Extension– Straightensjointandreturnsbodyparttoanatomicalposition

– Ex)straightentheelbow• Hyperextension– Extensionofjointbeyond180o

– Ex)lookingupwardattheceiling

AbductionandAdduction,ElevationandDepression

• Abduction– Movementawayfromthemedianplane– Ex)Raisingarm

• Adduction– Movementtowardthemedianplane– Ex)Loweringarm

• Elevation– Movementthatraisesbonevertically– Ex)shruggingshoulders

• Depression– Movementthatlowersbonevertically– Ex)loweringmandibletoopenmouth

Protraction,Retraction,LateralandMedialExcursion

• Protraction–Movementofboneforwardonahorizontalplane– Ex)thrustingpelvisforward

• Retraction–Movementofboneposteriorly

• Lateralandmedialexcursion– Lateral:Sidewaysmovementrightorleft–Medial:Movementbacktomidline– Ex)sidetosidegrindingofteeth

CircumductionandRotation,SupinationandPronation

• Circumduction– Movementconscribesaconicalspace– Ex)windingupforapitch

• Rotation– Boneturnsonitslongitudinalaxis– Ex)twistingatwaist

• Supination(forearmonly)– Rotationofforearmsothatpalmfacesforwardorupward

• Pronation(forearmonly)– Rotationofforearmsothatpalmfacestowardrearordownward

OppositionandReposition,DorsiflexionandPlantarFlexion

• Opposition–Movementofthumbtowardfingertips

• Reposition–Movementofthumbbacktoanatomicalpositionparalleltoindexfinger

• Dorsiflexion– Upwardmovementoffoot

• Plantarflexion– Steppingdownward

InversionandEversion

• Inversion– Turningsolesoffeetinwardmediallytowardeachother

• Eversion– Turingsolesoffeetoutwardawayfromeachother

LeverSystems

• Components1. Rigidrod:thestationarybone2. Effort• appliedforce:suppliedbymusclecontraction

3. Fulcrum• pivotpoint:joint

4. Resistance• theloadmovedbytheappliedforce• themovableboneandanythingattached

FirstClassLevers

• Fulcrumpositionedbetweeneffortandresistance

• Jointworkslikeasee-saw

• Example– atlanto-occipitaljoint(nodding)

SecondClassLevers

• Resistancepositionedbetweentheeffortandfulcrum

• Jointworkslikeawheelbarroworcrowbar

• Example– contractionofthecalfmusclestoelevatethebody

ThirdClassLevers

• Effortpositionedbetweenthefulcrumandresistance

• Mostcommon• Jointworkslikeforceps• Example– elbowjoint

RangeofMotionvsPower

• Rangeofmotionandspeed– Varietyofmovements– Numberofmovementsperunittime

• Power(leverage)– theamountofforce

• Effortclosertothefulcrum(3rd class)– increasesrangeofmotionandspeed

• Resistance(load)closertothefulcrum(2ndclass)

– increasespower