AnteriorandMedialRegionofThigh

LearningObjiective

1.Knowthestructuresformedbythedeepfasciaofthethigh(saphenoushiatusandiliotibialtract).

2.Knowthecontentsofanterior,medialandposteriorfascialcompartmentofthethigh.

3.Mastertheboundariesandcontentsofthefemoraltriangle

4.Knowthecompositionandcontentsofthefemoralsheath.

5.Mastertheboundariesofthefemoralring.

6.Masterthebeginning,endingandbranchesofthefemoralartery.

7.Mastertheorigin,branchesanddistributionofthefemoralnerve.

8.Mastertheboundariesandcontentsoftheadductorcanal.

9.Knowthebeginning,branchesanddistributionoftheobturatornerveandartery.

Keystone

1.Theboundariesandcontentsofthefemoraltriangle

2.Thecompositionandcontentsofthefemoralsheath.

3.Thecompositionandcontentsofthefemoralcnanl

4.Theboundariesandcontentsoftheadductorcanal.

QuestionsRequiringShortAnswer

1.Describetheboundariesandcontentsofthe①femoraltriangle;②adductorcanal.

2.Describethebeginnings,courseandendingsofgreatersaphenousveins.

3.Apatientisstabbedinthethighjustbelowthemiddleoftheinguinalligament.Whatstructuresareindamage?Whatwillbetheeffectofsectionofthemajornervehere?

ReadingandComprehension

I.Superficialstructures

Ⅰ)Cutaneousnerves

1.Lateralcutaneousn.ofthethigh

(1)Abranchofthelumberplexus

(2)Suppliestheskinofthelateralaspectofthethighandknee

2.Intermediatecutaneousn.ofthethigh

3.Medialcutaneousn.ofthethigh

Ⅱ)Thegreatsaphenousvein

1.Beginsthemedialendofdorsalvenousarchoffood

2.Passesanteriortothemedialmalleolusandascendsonthemedialsideoftheleg,thenpassesbehindthekneeandcurvesforwardaroundthemedialsideofthethigh

3.Inclinesanteriorlythroughthethightoenterthefemoralveinthroughthesaphenoushiatuswhichliesabout4cmbelowandlateraltothepubictubercle

4.Tributaries:

(1)Externalpudendalv.

(2)Superficialepigastricv.

(3)Superficialiliaccircumflexv.

(4)Superficialmedialfemoralv.

(5)Superficiallateralfemoralv.

Ⅲ)Superficialinguinallymphnodes:

1.Horizontalgroup:

(1)Liesjustbelowandparalleltotheinguinallig.

(2)Receivelymphfromanteriorabdominalwallbelowumbilicus,glutealregion,perinealregion,externalgenitalorgan

2.Verticalgroup:

(1)Liesalongtheterminalpartofthegreatsaphenousv.

(2)Receivesmostofthesuperficiallymphvesselsoflowerlimb

(3)Efferentvesselsdrainintothedeepinguinalln.orexternaliliacln.

II.Deepstructures

Ⅰ)Deepfascia–fascialata

1.Enclosesthethighlikeatrouserleg.

2.Laterallythedeepfasciaformsathickband,theiliotibialtract,fromtheiliactubercletothelateralcondyleoftibial.

3.Saphenoushiatus

(1)Agapinthedeepfasicawhichliesabout4cmbelowandlateraltothepubictubercle

(2)Falciformmarginisthelowerlateralborderoftheopening,whichliesanteriortothefemoralvessels.Thesaphenousopeningisfilledwithlooseconnectivetissuecalledthecribriformfascia

4.Thefascialatasendsintermuscularseptatothelineaasperaofthefemur.Theseseparatethethighintothreecompartmentseachofwhichcontainsagroupofmuscles,thevesselsandthenerves.

Ⅱ)Contentsoftheanteriorfascialcompartmentofthethigh

1.Muscles

(1)Sartorius

(2)Quadricepsfemoris

1)Origin:

Rectusfemoris:anteriorinferioriliacspine

Vastusmedialis:mediallipoflineaaspera

Vastuslateralis:laterallipoflineaaspera

Vastusintermedius:anteriorsurfaceoffemur

2)Insertion:tibialtuberosityviapatellarligament

3)Action:extendslegatkneejoint;rectusfemorisalsoflexesthighathipjoint

4)Nervesupply:femoraln.

(3)Iliopsoas

2.Nervesupply:lumbarplexus

3.Bloodsupply:femoralartery

Ⅲ)Contentsofthemedialfascialcompartmentofthethigh

1.Muscles

2.Bloodsupply:Profundafemorisa.andobturatora.

3.Nervessupply:obturatorn.

Ⅳ)Lacunamusculorum

1.Boundedbylateralportionofinguinalligamentanteriorly,iliumposterolaterally,iliopectinalarchmedially

2.Contents:iliopsoas,femoraln.andlateralfemoralcutaneousn.

Ⅴ)Lacunavasorum

1.Boundedbymedialportionofinguinalligamentanteriorly,pectinealligamentposteromedially,lacunarligamentmedially,andiliopectinalarchposterolaterally

2.Contents:femoralsheath,femorala.andv.,genitalbranchofgenitofemoraln.andlymphaticvessels

Ⅲ.Femoraltriangle(upperthirdoffrontofthigh)

Ⅰ)Boundries:Boundedbyinguinalligamentabove,medialborderofsartoriuslaterally,andmedialborderofadductorlongusmedially.Anteriorwallisformedfascialata.Posteriorwallisformedbyiliopsoas,pectineusadductorlongusandtheirfascia.

Ⅱ)Contents(lateraltomedial):femoraln.,femorala.,femoralv.andfemoralcanalcompartmentalizedwithinthefemoralsheath

Ⅲ)Femoralsheath

1.Afunnel-shapedsheath

2.Derivedfromtransversalisfasciaanteriorlyandiliacfasciaposteriorl

3.Itsurroumdsthefemoralvesselsandlymphaticabout2.5cmbelowertheinguinalligamemt.

4.Itslowerenddisappearsatthelowermarginofthesaphenousopeningwherethesheathfuseswiththeadventitiaofthevessels.

5.Dividedintothreecompartmentsbytwofibroussepta

(1)Thefemoralarteryoccupiesthelateralcompartmentofthesheath.

(2)Thefemoralveinliesthemiddlecompartment.

(3)Themedialcompartmentissmall,calledthefemoralcanal.

Ⅳ)Femoralcanal

1.Short,blindandpotentialspace,maybesiteoffemoralhernia

2.About1.3cmlong,anditsupperopeningiscalledthefemoralring.

3.Femoralring:formedbyinguialligamentanteriorly,lacunarligamentmedially,pectineallibamentpoateriorly,femoralveinlaterally;coveredbyfemoralseptum

4.Contains:alittleloosefattytissue,asmalllymphnode,andsomelymphvessels

5.Femoralhernia

1)Ifaloopofintestineisforcedintothefemoralring,itexpandstoformaswellingintheupperpartofthethigh.Suchaconditionisknownasafemoralhernia.

2)Afemoralherniaismorecommoninwomenthaninmen(possiblybecausetheirwiderpelvisandfemoralcanal).

6.Femoralartery

(1)Thisisthemainarteryofthelowerlimbandisdirectlycontinuouswiththeexternaliliacarteryoftheabdomenbehindtheinguinalligamentatthemid-inguinalpoint.

(2)Itbecomesthepoplitealarterybypassingthroughtheadductortendinousopening.

(3)Principalbranch－profundfemorisartery

1)Arisesfromtheposterolateralsideofthefemoralarteryabout4cmbelowtheinguinalligament.

2)Itgivesoff

①Lateralcircumflexartery:Itarisesfromtheprofundanearitsoriginandrunslaterallyamongthebranchesofthefemoralnerveandthendeeptorectusfemoris.Hereitdividesintoascending,transverse,anddescendingbranches.

②Medialcircumflexartery:ariseseitherfromtheprofundanearitsoriginoroccasionallydirectfromthefemoralartery.

③Threeperforatingarteries

3)Itendsbybecomingthefourthperforatinga.

7.Femoralvein

(1)Thisisthedirectcontinuationofthepoplitealvein.

(2)Itbeginsattheadductortendinousopeningandaccompaniesthefemoralarterytotheinguinalligamentbehindwhichitbecomestheexternaliliacvein.

(3)Thefemoralveincontainsseveralvalves.

8.Thedeepinguinallymphnodes

(1)Liemedialtothefemoralv.

(2)Receivedeeplymphaticsoflowerlimb,perinealregion,andefferentlymphaticsfromthesuperficialinguinalln.

(3)Efferentlymphvesselsdrainintotheexternaliliacln.

Threeorfourdeepinguinallymphnodesliealongthemedialsideofthefemoralvein.

9.Femoralnerve

Itarisesfromthelumbarplexusintheabdomen,andentersthethighposteriortotheinguinalligamentandlateraltothefemoralartery.Itendsbydividingintoanumberofbranches2cmbelowtheinguinalligament.

(1)Muscularbrancheto:pectineus,sartorius,quadricepsfemoris

(2)Cutaneousbranches:

1)Anteriorcutaneousnervesofthethigh(medialandlateral).

2)Saphenousnerveisthelongestbranchofthefemoralnerve.Itaccompaniesthefemoralvesselsintheadductorcanal,thenaccompaniesthegreatsaphenousveintothemedialsideofthelegandfood.

Ⅴ)Adductcanal(middlethirdofmedialpartofthigh)

1.Extendsfromapexoffemoraltriangletoadductorhiatus

2.Boundedbyvastusmedialislaterally,adductorslongusandmagmusposteriorly,andadductorlaminaandsartoriusanteriorly

3.Contents–saphenousnerve,femorala.,femoralv.,lymphaticvessels,andlooseconnectivetissue

Ⅳ.Bloodvesselsandnerveofmedialsideofthigh

Ⅰ)Obturatora.:arisesfrominternaliliacarteryinthelesserpelvis,passesthroughtheobturatorcanalwhereitdividesintoanteriorandposteriorbranches.

Ⅱ)Obturatorn.:arisesfromthelumbarplexusintheabdomen.Itentersthethighthroughtheobturatorcanalwhereitdividesintoanteriorandposteriorbranches.Theanteriorbranchdescendsanteriortotheadductorbrevis.Theposteriorbranchdescendsbetweenadductorsbrevisandmagnussupplyingboth.

Frontoftheleganddorsumofthefoot

LearningObjiective

1.Knowthecontentsofanteriorandlateralfascialcompartmentoftheleg.

2.Masterthebeginning,endingandbranchesoftheanteriortibialartery.

3.Masterthedistributionsofthesuperficialanddeepperonealnerves.

4.Mastertheinnervationofthemusclesoftheleg.

5.Knowthebeginning,endingandbranchesofthedorsalispedisartery.

Keystone

1.Thecontentsofanteriorandlateralfascialcompartmentofleg.

2.Thedistributionsofthesuperficialanddeepperonealnerves.

3.Thebeginning,endingandbranchesoftheanteriortibialartery.

4.Thebeginning,endingandbranchesofthedorsalispedisartery.

QuestionsRequiringShortAnswer

1.Describethedistributionsofthesuperficialanddeepperonealnerves.

2.Describethebeginning,endingandbranchesoftheanteriortibialartery.

3.Describethebeginning,endingandbranchesofthedorsalispedisartery.

ReadingandComprehension

Ⅰ.Superficialstructures

Ⅰ)Superficialveins

1.Thedorsalvenousarchliesonthedistalpartsofthebodiesofthemetatarsals.Itdrainsthedorsumofthefootandtoes.

2.Thesmallsaphenousveinrunsposteriorly,passingfirstinferiorandthenposteriortothelateralmalleolus.Itascendstothepoplitealfossainthebackoftheleg.

3.Thegreatsaphenousveinpassesposterioriyonthemedialsideofthefoot.Itascendsanteriortothemedialmalleolus,thenobliquelyacrossthedistalthirdofthemedialsurfaceofthetibia.

Ⅱ）Cutaneousnerves

1.Theuppertwo-thirdsofthefrontofthelegissuplliedbythesaphenousnerve(L3,4)medially,andthelateralcutaneousnerveofthecalflaterally.

2.Thelowerthirdissuppliedbythesuperficialperonealandsaphenousnerves.

3.Thedorsumofthefootismainlysuppliedbythemedialandintermediatecutaneousbranchesofthesuperficialperonealnerve.However,thelateralmarginissuppliedbythesuralnerveandthemedialmarginbythesaphenousnerveproximallyandthesuperficialperonealdistally.

4.Thefirstinterdigitalcleftandtheskinimmediatelyproximaltoitaresuppliedbythedeepperonealnerve.

Ⅱ.Deepstructures

Ⅰ)Deepfascia

1.Thedeepfasciasurroundsthelegandformstwointermuscularseptatobeattachedtothefibula.Dividedthelegintothreecompartments－anterior,lateralandposterior－eachofwhichcontainsagroupofmuscles,thevesselsandthenerves.

2.Attheankleitformsthickenedbands(retinacula)whichholdthetendonsdosetothejointandpreventthemfromspringingforwardsindorsiflexionoftheankle.

3.Superiorextensorretinaculumisabroadbandwhichextendsbetweenthefibulaandtheanteriorborderofthetibia.

4.InferiorextensorretinaculumisY-shaped.ThestemoftheYisattachedtotheuppersurfaceoftheanteriorpartofthecalcaneus.Medially,thelimbsoftheYseparate.Theupperisattachedtothemedialmalleolus,thelowerpassestothemedialsideofthefootandfuseswiththefasciaofthesole.

Ⅱ)Contentsoftheanteriorfascialcompartmentoftheleg

1.Muscles:

(1)Tibialisanterior

1)Origin:lateralsurfaceoftibia

2)Insertion:medialcuneiformandbaseof1stmetatarsal

3)Action:dorsiflexesandinvertsfoot

4)Nervesupply:deepperonealn.

(2)Extensordigitorumlongus

(3)Extensorhallucislongus

(4)Peroneustertius

2.Bloodsupply:

(1)Anteriortibiala.

1)Fromthepopliteaiarteryatthelowerborderofpopliteus.

2)Itpassesforwardsabovetheinterosseousmembrane,andturnsdownwardsontheanteriorsurfaceofthatmembranewiththedeepperonealnerve.

3)Itbecomesthedorsalispedisartery,midwaybetweenthemalleoli.

(2)Theanteriortibialveinsarecloselyappliedtotheartery.

3.Nervesupply:deepperonealnerve

(1)Itarisesfromthecommonperonealnervebetweentheneckofthefibulaandtheperoneuslongusmuscle

(2)Itdescendsintheanteriorcompartmentofthelegwiththeanteriortibialvessels.

(3)Itsuppliesallthemusclesoftheanteriorcompartmentofthelegandextensordigitorumbrevis.

(4)Ifthenerveisdestroyed,dorsiflexionoftheankleandextensionofthemetatarsophalangealjointsislost,andinversionisweakenedtheconditionknownas‘dropfoot’.

Ⅲ)Contentsofthelateralfascialcompartmentoftheleg

1.Muscles

(1)Peroneuslongus

(2)Peroneusbrevis

2.Bloodsupply:branchesfromtheperonealartey

3.Nervesupply:superficialperonealnerve

(1)Abranchofthecommonfibularn.

(2)Suppliestheperoneuslongus,peroneusbrevisandskinofthedistalpartoftheanteriorsurfaceofthelegandnearlyallthedorsumofthefoot.

Ⅳ)Dorsumofthefoot

1.Musclesofthedorsumofthefoot:

(1)Extensordigitorumbrevis

Action:extensionoftheinterphalangeaiandmetatarsophalangealjointsofthesecond,third,andfourthtoes.

(2)Extensorhallucisbrevis

Action:itextendsthemetatarsophalangealjointofthebigtoe.

2.Nervesupply:thedeepperonealnerve.

3.Dorsalispedisartery

(1)Itbeginsontheanteriorsurfaceoftheanklejointandrunswiththedeepperonealnerve

(2)Itdividesintothearcuatearteryandthefirstdorsalmetatarsalarteryattheproximalendofthefirstintermetatarsalspace.

(3)Onthedorsumofthefootitliesonthetarsalbonesandisreadilypalpatedagainstthembetweenthetendonsofextensorhallucislongusandextensordigitorumlongus

TheGlutealRegionandBackofThigh

LearningObjiective

1.Knowthename,positionandnervesupplyofmusclesoftheglutealregion.

2.Mastthestructuresthestructurespassingthroughthesuprapiriformforamen.

3.Mastthestructurespassingthroughtheinfrapiriformforamenandlessersciaticforamen.

4.Mastertheorigin,courseanddistributionofthesciaticnerve.

5.Knowcontentsofposteriorfascialcompartmentofthethigh.

Keystone

1.Thestructuresthestructurespassingthroughthesuprapiriformforamen.

2.Thestructurespassingthroughtheinfrapiriformforamenandlessersciaticforamen.

3.Theorigin,courseanddistributionofthesciaticnerve.

QuestionsRequiringShortAnswer

1.Describethestructurespassingthroughthesuprapiriformforamenandinfrapiriformforamen.

2.Describetheborigin,courseanddistributionofthesciaticnerve

ReadingandComprehension

Ⅰ.Theglutealregion

Ⅰ)Boundaries:

1.Superiorly:iliaccrest

2.Inferiorly:foldofbuttock

Ⅱ)Cutaneousnerves:Superiorclunealn.,Medialclunealn.,Inferiorclunealn.

Ⅲ)Musclesoftheglutealregion

1.Gluteusmaximus

(1)Origin:glutealsurfaceofiliumanddorsalaspectofsacrum

(2)Insertion:glutealtuberosityoffemurandiliotibialtract

(3)Action:extendsandlaterallyrotatesthighathipjoint;raisestrunkwhenthelowerlimbisfixed

(4)Nervesupply:inferiorglutealn.

2.Gluteusmedius

3.Gluteusminimus

4.Piriformis

5.Tensorfasciaelatae

6.Obturatorinternus

7.Quadratusfemoris

Ⅳ)Structurespassingsuprapiriformforamen:superiorglutealn.,a.,v.fromlateraltomedialside

Ⅴ)Structurespassinginfrapiriformforamen:sciaticn.,posteriorfemoralcutaneousn.,inferiorglutealn.,a.,v.,internalpudendalv.,a.,andpudendaln.fromlateraltomedialside.

Ⅵ)Pudendalnerve,internalpudendalartery

Thesestructuresentertheglutealregionthroughtheinfrapiriformforamen.Theythencurveforwardstoentertheperineumthroughthelessersciaticforamen.

Ⅶ)Nervesoftheglutealregion

1.Sciaticnerve

(1)Course:Itarisesfromthesacralplexusandpassesthroughinfrapiriformforamenintotheglutealregion,deeptogluteusmaximus,passingmidwaybetweenthegreatertrochanteroffemurandischialtuberositytobackofthigh,thenerveliesdeeptothelongheadofbicepsontheposteriorsurfaceofadductormagnus.Thesciaticnerveusuallyendshalf-waydownthebackofthethighbydividingintothecommonperonealandtibialnerves.

(2)Distribution:semitendinosus,semimembranosusandbicepsfemorisandhasarticularbranchestohipandkneejoints

(3)Relationshipofsciaticn.tothepiriformis:Occasionally,thesciaticn.dividesintoitstwoterminalpartsatahigherlevel－intheupperpartofthethigh,theglutealregion,oreveninsidethepelvis.

2.Posteriorcutaneousnerveofthethigh

(1)Arisesfromthesacralplexus

(2)Leavesthepelvisthroughthelowerpartofthegreatersciaticforamen

(3)liesonthesciaticnerveoralongitsmedialborder.Itthenrunsdownthemiddleofthebackofthethighimmediatelydeeptothedeepfascia

(4)Itpiercesthedeepfasciaatthebackofthekneeanddescendsasfarasthemiddleofthebackofthecalf.

3.Superiorglutealnerve

Thisbranchofthesacralplexusenterstheglutealregionthroughtheuppermostpartofthegreatersciaticforamen;suppliesgluteusmediusandminimusandtensorfasciaelatae

4.Inferiorglutealnerve

Thisbranchofthesacralplexusenterstheglutealregioninferiortopiriformis.Itsuppliesgluteusmaximus.

5.Pudendalnerve

Entertheglutealregionthroughthelowestpartofthegreatersciaticforamen;thencurveforwardstoentertheperineumthroughthelessersciaticforamen.

Ⅱ.Contemtsoftheposteriorfacialcompartmentofthethigh

Ⅰ)Muscles

1.Bicepsfemoris

2.Semitendinosus

3.Semimembranosus

Ⅱ)Bloodsupply－branchesofthedeepfemoralartery

Ⅲ)Nervesupply－sciaticnerve

TheBackoftheLeg

LearningObjiective

1.Mastertheboundaryandcontentsofthepoplitealfossa.

2.Knowcontentsofposteriorfascialcompartmentofleg.

3.Masterthebeginning,endingandbranchesoftheposteriortibialarteriy.

4.Masterthedistributionsofthetibialnerve.

5.Masterthestructuresthatpassthroughthemalleolarcanal.

Keystone

1.Thedistributionsofthetibialnerve.

2.Thebeginning,endingandbranchesoftheposteriortibialarteriy.

3.Theboundaryandcontentsofthepoplitealfossa.

5.Theboundaryandcontentsofthemalleolarcanal.

QuestionsRequiringShortAnswer

1.Describetheboundaryandcontentsofthepoplitealfossa.

2.Describetheboundaryandcontentsofthemalleolarcanal.

3.A20-year-oldstudenttwistshisankleplayingbasketball.Thereismarkedtendernessanteriortothelateralmalleolus.Namethebonesconstitutingtheanklejointandstatetheinjurythathasoccured.Listthemusclegroupactingonthejointandgivetheirnervesupply.

ReadingandComprehension

Ⅰ.Poplitealfossa－diamond-shapedintermuscularspacesituatedatthebackoftheknee

Ⅰ)Boundariesofthepoplitealfossa

1.Superolaterally:Bicepsfemoris

2.Superomedially:semimembranosusandsemitendinosus

3.Inferiorly:lateralandmedialheadsofgastrocnemius

4.Roof:deepfascia

5.Floor:poplitealsurfaceofthefemur,theposteriorcapsuleofthekneejoint,andthefasciacoveringpopliteus

Ⅱ)Contentsofthepoplitealfossa

1.Tibialandcommonperonealnervesandtheirbranches

(1)Tibialnerve

1)Itisthelargerofthetwoterminalbranchesofthesciaticnervewhichseparateaboutthelowerthirdofthethigh

2)Itrunsverticallythroughthepoplitealfossa,posteriortothepoplitealvessels.

3)Branchesinthepoplitealfossa::

①Suraln.descendsbetweenthetwoheadsofthegastrocnemiusandisusuallyjointedbythesuralcommunicatingbranchofthecommonperonealn.

②Muscularbrachessupplybothheadsofthegastrocemiusandplantaris,soleus,andpopliteus

③Articularbranchessupplythekneejoint

(2)Commonperonealnerve

1)Itrunsalongthemedialborderofthebicepsfemoristothebackoftheheadofthefibula.Itthencurvesforwardsbetweentheneckofthefibulaandtheupperfibresoftheperoneuslongusmuscle.Herethenervedividesintosuperficialanddeepperonealnerves.

2)Branchensinthepoplitealfossa:

①peronealcommunicatingnerve

②lateralcutaneousn.ofthecalf

③muscularbranch

④articularbranches

2.Poplitealveinanditstributaries

(1)Formedbythejunctionoftheanteriorandposteriortibialveinsnearthelowerborderofthepopliteusmuscle.

(2)Liesbetweenthetibialn.andpopliteala.throughoutitscourse

(3)Passesthroughtheopeningintheadductormagnustobecomethefemoralv.

3.Deeppopliteallympnnodes

(1)Theremaybe4-5nodesjustunderthedeepfascia,closetothepoplitealfossavessels.

(2)Receivesuperficiallymphvesselsfromthelateralsideofthefootandleg;alsoreceivelymphfromthekneejointandfromdeeplymphvesselsaccompanyingtheanteriorandposteriortibialvessels.Efferentspasstothedeepinguinallymphnode

4.Poplitealarteryanditsbranches

(1)Entersthepoplitealfossathroughtheopeningintheadductormagnus,asacontinuousofthefemoralartery.Itendsatthelowerborderofthepopliteusmusclewhereitdividesintoanteriortibiala.andposteriortibiala.

(2)Branches:

1)Superior,inferior,andmiddlegeniculararteries

2)Muscularbranches

5.Fattytissue

Ⅱ.Thebackoftheleg

Ⅰ)superficialstructures

1.Cutaneousnervesofthebackoftheleg

(1)Suraln.,abranchofthetibialnerve,supliestheskinonthelowerpartoftheposterolateralsurfaceoftheleg

(2)Peronealcommunicatingn.,arisesfromthecommonperonealnerveinthepoplitealfossa,anddescendstojointhesuralnerve.

(3)Lateralcutaneousn.ofthecalf,abranchof