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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