Chapter 2 Arthrologyor immovable joint, and diarthrosisormovable joint.Section 1GeneralDescriptionI . SynarthrosisIn order to serve their prime functions,bonesThe synarthrosis occurs between the bones thatmust be joined together one another by various softare in almost direct contact,fastened togetherby in-tissue structures at where they meet, and such connec-tervening connective tissue or hyaline cartilage, andtions are termed Joints or Articulations.According tothere is no space and appreciable motion betweenthe nature of the intervening soft tissues,joints can bebones. It includes the fibrous joints, cartilaginousclassified intofibrous joints,cartilaginous joints,andjoints, and synostoses (Fig.I-2-1)synostoses. They can also be classified according totheirrelativefreedom of movement into synarthrosisFibrous membraneSynovialmembraneSyndesmosesArticularcavityGomphosisArticular cartilagePubicsymphysiFig.I-2-1 The classification of jointsjoints in common: suture, syndesmosis and gompho-sis.Fibrous jointsI) Sutures ' In this kind of fibrous joints, bonesare united by a thin layer of fibrous tissue. It is metThebones are connected by intervening densefwith only in theskull, such as the sagittal and coronalbrouscoivtiseasednthhsutures. The fibrous tissue is continuous externallybesunihbhreaees ffuswith the pericranium, intermally with the dura mater.·55·-扫描全能王创建
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.56·PARTI LOCOMOTORSYSTEMnovialcavity, thecontiguousbonysurfasare covWith age, the fibrous tissue is gradually replaced byered with articularcartilag,andcontedbyasurbone and many sutures become a completely bonyroundingcapsuleofdensefbroustissueandisalsoconnection or synostosis.There is a little or no move-calledthesyovial jointulasurfacearticularment between the bones.capsuleand aricularcavity are thecharacteristisof2) SyndesmosisThe bone are united by a vis-synovialjoint. This class includes the greater numberible and elastic ligaments or membrane, such as theof the joints in the body. Synovial joints provide variinterspinal ligament joining the adjacent spinousous movement between the bones. However, the actu.processes, and the interosseous membrane offorearmal range ofmovement depending on the requirementsconnecting the shafts of radius and ulna.Syndesmosisfor function and stability.permits a slight degree of movement.3)GomphosisIt is articulation by the insertionEssential structures of synoviaof a conical process into a socket and is seen in thearticulations of the roots of the teeth with the alveolijointsof the mandible and maxilla.1) Articular surfaceThe articular surface isthe corresponding surfaces of the joining bones, one.Cartilaginous jointsusually convex, called articular head, the other concave, called articular fossa. Articular cartilage coversThe connecting medium is cartilage. There arethe surfaces, and in most joints, is hyaline cartilage.twotypes:synchondrosesand symphysis.They allowThe articular cartilage is very smooth and uneven inlittleornomovementbetweenthebones.the thickness, it can decrease the friction and absorb1)SynchondrosesThebones arejoined bythe shake occurred between the articular surfacesa plate of hyaline cartilage.Such joints are foundArticular cartilageisfreeof blood vessels andnerves,between the occipital and the sphenoid bones, theits nourishment being largely dependent on synovialribs and the sternum, and between the adjacent en-fluid. Once being damaged, articular cartilage doesdochondral centers of ossification,for example,thenot regenerate (Fig. I- 2-2).epiphysial cartilage plate between the epiphyses and2) Articular capsuleThe articular capsulesshafts of long bones. Synchondroses occur in embryo,form complete envelopes for the freely movableand with age, the cartilage is eventually convertedjoints. It consists of an outer layer of fibrous memintoboneforming synostosis,or transformed intofi-brane and an inner lining of synovial membrane. Thebrocartilageformingthesymphysis,synchondrosearefibrous membrane is attached to the whole circumfertemporary joint.ence of the articular end of each bone entering into2) Symphysis The bones are joined by a broad,thejoint and adjacentbonesurface, whereitcontinuesflatdisc offibrocartilage.Itmaybe amore orless com-to the periosteum. It is composed of dense connecplex structure,such as the intervertebral disc joining thetive tissue and isricher in blood vessels and nervesbodies of thevertebraeand permitting the columntoThe symovial membraneinvests the inner surfaceofthebend; or the pubic symphysis connecting the pubis.Thefbrouscapsuleefortaicularsurfaceandsymphysis is not ossified throughout the life.refectedover anytendons pasing throughthejointcaityIislyrryhindelicatecntivetss3.Synosteosiswhich secrets syovialfuid (syoviathat fllsthearicular cavity and lubricates the joint (Fig. I-2-2)The bones are united by the ossification of the3)Articular cavityThe articularcavity isfibrous joint or synchondroses between them. Suchclosedspacefomedbythesynovialmembrane anda joint occur at sacrum between the sacral vertebraethaalanmand at acetabulum uniting ilium, ischium and pubis.ialdothbriajnandatvpressurenhcaiyshelufothesabilII.Diarthrosesof the joint (Fig.I-2-2),The bones of a diarthrosis are separated by a sy-扫描全能王创建
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Chapter2Arthrology·57.TAVOFibular collateral ligIntracapsular lig-IntracapsularcartilageSynovial foldTibial collatral ligFibrous membraneFibrous membraneArticularcapsuleSynovialmembraneSuprapatellarbFibrousmembranePatellaArticular capsuleSynovial membraneIntracapsular cartilagePatellar synovial foldArticular cartilageFig.I-2-2Structures ofa typical synovial jointthe attachment of their margins and extremities to thesurrounding articular capsule and ligaments.In knee2.Accessory structures of synovialjoints, the pad is called semilunar articular meniscus.The disc can divide the articular cavity completely orjointsincomplctely into two compartments.Their actionsare to obliterate the intervals between opposed sur-1)LigamentsThe ligaments are bundles offaces in their various motions; to increase the depthsdense connective fibrous tissue, which strengthen theof the articular surfaces and give ease to the glidingjoint either inside or outside it.They are divided intomovements; to moderate the effects of great pressureintracapsular and extracapsular ligaments.The liga-and deaden the intensity of the shocks. So it serves anments increase the stability and prevent over move-important purpose in increasing the varicties ofmove-ment of joints (Fig.I-2-2).ment in a joint (Fig.I-2-2).2)Articular disc In some joints, such as sterno-The articular labrum isa3)Articularlabrumclavicuar joint and temporomandibular joint,there ispliable fibrocartilaginous ring that surrounds the mar-fattened fibrocartilaginous plate named articulardiscgins ofsomeofthe articular surfaces,e.g. the acetabbetween the articular surfaces of the bones.They areular labrum of the hip joint and the glenoid labrum offeeon both surfaces,usually thinnertoward thecenthe shoulder joint, They serve to deepen the articularter than at the circumference,and hold in position by2口扫描全能王创建口
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·58·PARTI LOCOMOTORSYSTEMthe body is abduction.surface and to protect their edges.4) RotationTherotation occurs when a bone4) Synovial fold In some ofthe joints,especial-spins around a central longitudinal axis without unly in theknee, the synovial membrane isthrown intodergoing any displacement from this axis.The axisfolds which pass across the cavity,named Synovialof rotation may lie in its own, in a separate bone,orfold. The larger fold often contains considerablein both, as in the cases of the humerus rotating at thequantities of fat, called synovial fat cushion (Fig.I-shoulder joint, the atlas rotating around the dens of2-2),axis, and the radius rotating around the ulna during5) Synovial bursa Some joints have closed,pronation and supination of the forearm.fluid filled sacs, called Synovial bursae.They arePronation and supination The pronation and supiinterposed between surfaces that glide upon each oth-nation are movements specially for theforearm.Pro-er.The bursae are formed with synovial membrane,nation isrotation oftheforearm sothatthe palm faceswhich may be continuous with the synovial mem-backward, while the supination is tuning theforeambranes of the joint cavity.so that the palm faces forward.The circumductionisa5)Circumduction3.Types of joint movementsmovement in which the proximal end of a bone re-mains relatively stationary while the distalend movesThe movements at synovial joint,produced bythein a circular path. It is the harmonious combination ofactions of skeletal muscle,may be divided into fourflexion,abduction,extension and adduction,givingakinds:gliding and angularmovements,rotation andcompression of rotation as the bone circumscribes acircumduction.Thesemovements are often,however,conical space.more or less combined in the various joints, so as toproduce an infinite variety (Fig.1-2-3)Types of synovial jointsThegliding1)Gliding(orslipping)movement(orslipping)movementisthesimplestmovementAccording to the number of axes along which thebetween the two articulating surfaces. One surfaceglides or moves over another without any angular ormovementtake place,the synovial joints can be clas-rotatory movement.In the most of articulations ofsified into uniaxial, biaxial and polyaxial joints.the carpus and tarsus, it is the only motion permitted.(1) Uniaxial jointsThis movement is not confined to plane surfaces2)Flexion and extensionThese two antago-nistic movements are performed on the coronal axis.All movements of uniaxial joints take placeTheflexion is themovement that decreases the anglearound one axis (coronal, sagittal or vertical) . Thesebetweentheadjoining bones,as bendingthe elbowjoints are subdivided into two types.forward.The extension is themovement that increas-1) The hinge joint (or trochlear joint)is onees the angle between the adjoining bones,as straight-with concave and convex surfaces, and movementening the elbow.An exception for this is the ankletakinglaiaawjojoint, which has dorsiflexion (extending the foot atinterphalangeal joints of the hand.the ankle)and plantarflexion (flexing the foot at the2) The pivot joint is one with a ring encirclingankle).Both movements take place in one, usuallya pivot set on a vertical axis, e. g.,the radioulnar andthe coronal axis.the atlantoaxial joints (Fig.I-2-3)3)Adduction and abductionThe adductionThe movements permitted in a hinge joint areand abduction aretwoantagonistic movements per-flexion and extension; only one movement, rotation.formed on the sagittal axis, toward and from theccurs ipivot joingthroxmalradoumedian plane of the body, except in digits, wherejoint.arbitrary planes are chosen (midlines of the middledigit of the hand and second digit of the foot).For(2) Biaxial jointsexample, returning the arm from the horizontal posi-tion tothesideothebody isadduction, raising theThemovementsofbiaxial joints arepermitedarmhorizontally tofomarightanglewiththesideofaround twoaxes that lieat approximately straight口2扫描全能王创建
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Chapter2Arthrology·59.aneschothehey incudellipoidjonsorndyloid joint, and saddejoints orsellarjoints(Fig23)Trochoid joint (Pivot joint)Sellar joint (shaddle joint)CBall and socket jointEllipsoid jointHinge jointFig.I-2-3 The types of synovial jointsI) Ellipsoid joints or condyloid jointsIn thisare two sub-classes: one with a shallow articularfossa, such as shoulder joint; the other with a deeperfom ofjoint, an ovoid convex surface,or condyle, iarticularfossa, such as thehipjoints,in which thereceived into an elliptical concave cavity.One axis isarticularhead is embedded.Thedistal bone is capablealong the long diameter and the other along the shortof motion around an indefinite number of axes.diameter of the articular surfaces. The wrist and the2)Plane joints (or gliding joints)Theplanemetacarpophalangeal joints are examples of this typeariuaonFxndxanklajoints(orglidingjoints)areformedbytheappositionofplanesurfaces,andarereferredtomultiaxial joints.inthelong axisadductionandabuctioncanoccurinOnly a little ofmovement can take place in thiskindtheshort one,and socircumductionis allowedofarticulation,e.g.,the acromioclavicular joint2) Saddle joints or sellar jointsThe opposingsurfacesofsaddlejoints aresaddleshaped,achiSection 2Joints ofmaxmaynexinartculardirctionandimaximalyconcaveatright anglestothisdirectionSkullThtxmehsfomapmaapalThe joints of the skull are divided into three types:joinmhmsadejonsutures,cartilaginous and synovial joint.the sameas intheellipsoidjoints.The sutures of the skull include the coronal,sagittal, lambdoid and sphenoparietal sutures. The(3) Polyaxial jointscartilaginous joints in the skull are occipitosphenoid,petrosphenoid and occipitopetrous synchondrosis.Themovementsofthe polyaxial joints arepsiThe only synovial joint is the temporomandidularblearound immerable axes (Figl-2-3)joint (Fig.I-2-4).Theball)Ball and socket (spheroid) jointsThe temporomandibular joint consists of theakeokdyemandibular fossa and the articular tubercle of the tem-口A扫描全能王创建D5
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.60.PARTILOCOMOTORSYSTEMcle,belowtohelateralsurfaceandposteriorbordeporal bone above and the head of the mandible below.of the neck of the mandible.The sphenomandibularThe articular surfaces of the joint are covered byligament onthemedialsideofthe jointextendsfromfibrocartilage.The articular capsule is a thin,looseen-thespineofsphenoid bone totheramusofmandibie.velope, attached to the articular circumference of theThe stylomandibular ligament extendsfrom the apextemporal bone above and to the neck of the mandibleand adjacent anterioraspect ofthestyloidprocessofbelow.The joint is reinforced by two ligaments:Thethe temporal bone to the angle and posterior border oflateral ligamentoftemporomandibularjoint,closedtotheramus ofmandible.Itcanonly beconsidered asthe lateral side of the capsule, is attached above to theaccessory to it (Fig.I-2-4).lateral surface of the zygomatic arch and to the tuber-Articular cavityMandibularfossaArticular discLateral ligArticularStyloidprocesscapsuleStylomandibular ligHead ofmandibleFig.I-2-4 The temporomandibular jointThere is an articular disc in the articular cavity,byments are combined in grinding, biting, chewing, andwhich the joint can be divided completely into upperrotation.and lower parts.Thedisc is an oval plate of fibrocarti-The mandible is dislocated only forwards. A ex.lage.Its superiorsurface,toaccommodateitselftothetremely opening ofthe mouth may lead to slipping ofform of mandibular fossa and the articular tubercle,the head of mandible forwards into the infratemporalis sagittally concavo-convex; its inferior surface,infossa. Pulling the mandible down over the articularcontact with the condyle, is concave.tubercle while pushing the jaw backwards may reloThe movements ofthemandiblecan bedepress-cateit.ing or elevating,and protruding or refracting; and aslight amount of side to side movement and rotationSection3.Joints ofare also permitted. These actions involve gliding,Bones of Trunkspin,roll and angulation.Opening and closing of themouth are primarily hinge movements and are con-The vertebral column consists ofthe 24 pieces offined to thelower parts ofthe two joints, when thebae, thesacm andcccy which articulateoemouth is opened more widely,both upper and lowerby one to form a longitudinal axis ofthe trunk.Cranillyparts of the two joints are involved.In protrusion, theitsuporsthskullandlateraygivesaachmenttmovement takes place principally inthe upperpart ofribs.The verebralcolumnreceived the weight ofthethejoint,thedisc and thehead ofmadiblearepulledunk,hd adupper lm,aduallyitsudforward onto the articular tubercle.Inretraction,thewith the hip bones by which the weight of thetrunk.disc and the head of madible are moved backwardheadanduperlimsistranmiedothlowerlimbsintothe mandibularfossa.In lateralmovement oftheThevebralcanalgivessupporstothespinalmandible,thedisc andtheheadofmandiblerotateinosopinalandirrinrone joint andglideforwards intheother.Thesemovelocated within the canal.口扫描全能王创建口
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Chapter 2 Arthrology · 61 .I . Articulations of Verte-.Joints of vertebral bodiesbral ColumnThe adjacent vertebral bodies are mainly jointedby the intervertebral disc and reinforced by the anteri-The vertebrae articulate each other by interverte-orand posterior longitudinal ligaments(Fig.1-2-5,)bral discs, ligaments and synovial joints (Fig.-2-5)Anterior longitudinal ligAnnulus fibrosusNucleus pulposusVertebral foramenPosterior longitudinal lig.Ligamenta flavaFig. 1-2-5 The intervertebral discThe intervertebral discs vary in shape; size, and1) Intervertebral diseThe intervertebral disc isthickness, in different regions and within individuala symphysis interposed betweenthe adjacent surfacesdiscs.The shape and size of them correspond with theofthevertebral bodiesfromC2tothesacrum.ExceptSurfaces of the bodies between which theyare placed.at the sites of the uncovertebral joints of Luschka,Discs are thinnest in the upper thoracic region anddisc outlines correspond with the adjacent bodies.thickest in the lumbar region They are thicker in ante-Each intervertebral disc is composed, at the circum-rior part than posterior in cervical and lumbar regions,ference, of a tough lamellated fbrocartilaginous ringcontributing to the anterior convexities of these partscalled the annulus fibrosus and in the center, of aofthe column,but nearly uniform in thoracic regionmore pliable gelatinous mass named the nucleus pul-where the anterior concavity is largely due to the ver-posus (Fig.I-2-5).tebral bodies.The intervertebral discs constitute aboutThe nucleus pulposus ishighly plasticandistheone-fourth of the length of the vertebral column; theremainderof the notochord in embryo.The annuluscervical and lumbar portions have a much greaterfibrosus insert frmly into the brims ofthe upper andamount than the thoracic region,with the result thatlower surfaceoftheertebralbodyThesebrocartthese parts possess greater pliancy and freedom oflaginousrngs arecomposedofdensecollagenfbersmovement.rdarinra2)Anterior longitudinal ligament The anteriorintervertebral discs areimportant shockaborberslongitudinal ligament is a broad and strong band ofUnderpreurethehighlyelasticnucleus pulposusfibers,which extends along the anterior surfaces ofbomsfltterandbrader,ndpushsthmothe vertebral bodies and intervertebral discs from theresistant aulus fbrosus inalldirections.Therelabase of the skull to the pelvic surface of the first ortivelythinposteriorparofthannulusfbrosusmaysecond sacral vertebra. It is the longest ligament ofuptureetherduetotraumaortodegenerativechangthe body and broader below than above, thicker inauthoracic than in cervical and lumbar regions. The lig-ament is intimately adhered to the intervertebral discsdidestadand prominent margins of the vertebrae,but not to theamiddle parts of the bodies.This strong ligament mayofback20口扫描全能王创建
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·62·PARTI LOCOMOTORSYSTEMand thicker in thoracic than the cervical and lumbarprevent hyperextension of the vertebral column and isregions.Thisligamenttendstocheckthefexionandespecially important in the lumbar region, where theprevent hyperfexion ofthe vertebral column (Fig.l-2.weight of thebodytends to increasethenormal posture7)ofextensionofthelumbarspine(Fig.1-2-6,7)2.Joints of vertebral archesIntervertebralforamenInf.costalfoveaThe vertebral arches are connected by synovial4Sup.costal foveajoints between articular processes and by accessoryligaments that connect the laminae and all processes.Transverse castalfovea1) Zygapophysial jointsThe zygapophysialjoints are formed by opposing articular processes ofthe adjacent vertebrae.They are mostly of the glidingZygapophysialtype and move only slightly (Fig.1-2-6, 7) .joint2) Ligamenta flavaThe ligamenta fava con.nect laminae of adjacent vertebrae in the vertebral ca-nal.They are thick,yellow andelastic plates,descendfrom the lower anterior surface of one lamina to theFig.I-2-6 The joints of the vertebraeposterior surface and upper margin of the laminabelow, and extend from-zygapophysial joint capsules3)Posteriorlongitudinal ligamentTheposte-to the point where laminae fuse to form spines.It isrior longitudinal ligament is a narrowband lying oncontributed to part of the posterior boundary of thetheposteriorsurfaces ofthevertebral bodiesanddiscsvertebral canal and tends to prevent hyperflexion ofin the vertebral canal, attached between the body ofthe vertebral column.So it is the strongest and mostC2 and the sacrum,and continuous with the tectorialimportant ligament (Fig.1-2-5,7)membrane above. It is broader above than below,Posterior longitudinal lig.Nucleus pulposusIntervertebralforamenMCAnnulus fibrousACLInterspinous lig.aSpinous process物Intervertebral discLigamenta flaSupraspinous ligAnterior longitudinal lig.Fig.I-2-7 The joint and ligaments of the vertebrae3) Interspinous ligamentsThe interspinous lig-behind (Fig.I-2-7).aments are thin and membranous, which connect ad.4)Intertransverse ligamentsjoining spinous processes and extend ventrally fromThe intertrans-verse ligaments connt succeeding transverse prothe root to the apexof each process.They meet thecess and are functionally insignificantligamentafava infontand the supraspinalligament5) Supraspinal ligament (Fig.I-2-5, 7)The口S格扫描全能王创建合品
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Chapter2Arthrology .63supraspinal ligament isastrongfbrous cord,whichJoints of the atlas with the二conncts togethertheapicesofthespinousprocssesaxisfrom the seventh cervicalvertebratothesacrum.Itis continued upwardtotheexternaloccipital protuThe articulation of the atlas with the axis is aberanceandmediannuchalline,astheligamentumcomplicated nature,comprising four distinct joints.Except for the lateral atlantoaxial joints between thenuchae.6) Ligamentum nuchae The ligamentum nu-articular processes of the atlas and axis on both sides,chae isatiangularfbrous membrane, which extendsthere is a median atlantoaxial joint between the densfrom theexternaloccipitalprotuberanceandmediof the axis and the ring formed by the anterior archan nuchal line above, to the spinous process of theand the transverse ligament of atlas.The median atseventh cervical vertebra below, and tips of cervicallantoaxial joint includes two parts:One between thespinous process infront,Itformsamedian septumdental fovea and the dens, the other between the antebetween the musclesoneithersideoftheneck.Inhu-rior surface of the transverse ligament and the back ofman it is merely the rudiment of an important elasticthe dens.ligament, but in some of the lower animals, whichThe median atlantoaxial joint is reinforced by theserves to sustain the weight of the head.apical ligamentofdens,alarligaments and transverse7) Intertransverse ligaments The intertrans-ligamentof atlas (Fig.1-2-8):verse ligaments are interposed between the transverseprocesses.Basilarpart of occipital boneApical ligamentof densOccipital boneAlarligAtlautooccipital joint小鸟Transverselig,of atlasLateral atlantoaxial jointTectorialmembraneAxisFig.I-2-8Ligaments of atlantoaxial and atlantooccipital jointsIt is a thick3)Transverse ligament of atlasI) Apical ligament of dens It extends from theand strong band, which firmly attached to either me-tipof dens to the anterior margin of foramen magdial sides of the lateral mass of the atlas, and retainsum beingintimately bend withthedporiothe dens in contact with the anterior arch. As it cross-theanterioratlantoocipitalmmbranandsuperoes the dens,a small fasciculus prolongs upward, andcrusofthe transverseligamentofatlasanother downward from the superficial or posterior2)AlarligamentsThey arise fromeachsideoffibers of the ligament. The former is attached to thethperardnadpasbiquelyadbasilar part of the occipital bone, in close relatione asisowith the tectorial membrane; the latter is fixed to thetal condyles.口口扫描全能王创建D
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.64.PARTILOCOMOTORSYSTEMthe posteriorlongitudinalligament.It isfixed inferiposterior surface of the body-of the axis; hence theorly to the posterior surface of the body of the axis.whole ligament is named the cruciform ligament ofandexpanded superiorly, which attached to the basi-atlas.larparoftheocipitalboneInfrontoftheforamn4) Tectorial membraneThe tectorial mem-magnum it blends with the cerebral dura mater (Fig.brane is a broad, strong bands, which covers the densI-2-9).and its ligaments,and appears tobea prolongation ofMidian atlantoaxial jointAnteriorarchDensTransverselig.ofatlasTectorialmembranePosteriorarchA.superiorviewTectorialmembraneAnterioratlantooccipitalmembraneApical ligamentofdenPosteriorMedian atlantoaxial jointatlantooccipitalTransverselig.of atlasB.sagttal sectionFig.I-2-9 The atlantoaxial jointThe atlantoaxial joints allow the head toturnfromwith two ligaments: The anterior atlantoccipitalside to side.During this movement, the skull and atlasmembrane isthe upper part of the anterior longitudi-rotate as a unit on the axis.nal ligament, which located between the anterior mar.gin ofthe foramen magnum above, and the superior4. Joints of the vertebral columnborder of the anterior arch of the atlas below; laterallywith the craniumitiscontinuous withthearticularcapsulesofthealanoccipljointshosroratlantooccpiThe atlantooccipital joints are condyloid andmmbransboadbutthn,whichionnctedcooperated joints,formed by the occipital condylesposteriormarginoftheforamenmagnum aboveandandsuperiorarticularsurfacesoftheatlas.The jointstothesuperorbrderofthepserorarchofheaasallow the head bendforward, backward and laterally.below.The articular capsule of the joint is connected-扫描全能王创建口
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