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Lower Limbs 2 Surgical Society | Junior Anatomy Series Lecture8 7/02/2023 PresentedBy Anas Aboukoura Learning Objectives Structure of Structure of the Lumbo-sacralPlexus the session Femoral Nerve ObturatorNerve Sciatic Nerve Nerveinjury and assessinginnervation Arteries of the Lower Limb Veins and Lymphatics of the Lower Limb Summary and Practice Questions Surgical Society | Junior Anatomy SeriesLearning Objectives • Nerves of the Lower Limb: - Outline the general organisation of the lumbo-sacral plexus from its origins in the lumbar and sacral spine to its terminal branches. - Name the major terminal branches of the plexus: the sciatic (including its terminal branches, the tibial and common fibular nerves), femoral and obturator); describe their course in the limb, and outline their major motor and sensory innervation targets. - Identify points where major nerves are commonly damaged and outline the important motor and sensory consequences of such damage. Demonstrate the testing of motor innervation of the lower limb muscles by assessing the tone, power and eliciting tendon reflexes. Describe and demonstrate the general pattern of the dermatomes in the lower limb and demonstrate the testing of sensory innervation. • Arteries of the Lower Limb: - Describe the course and distribution of the major arteries and their main branches, identify where vascular structures are at risk of damage. - Demonstrate palpation of femoral, popliteal, posterior tibial and dorsalis pedis arterial pulses. • Veins and Lymphatics of the Lower limb: - Describe the course of the main veins of the lower limb and contrast the organisation and function of the deep and superficial veins; identify the common sites of venous access and describe their key anatomical relations. - Outline the anatomy of the lymph nodes and explain their importance in the lymphatic drainage of the lower limb in the spread of infection and malignancy. Recognise the importance of the inguinal nodes in draining pelvic structures. Surgical Society | Junior Anatomy Series Lumbo-sacral plexus • Somaticmotorandgeneralsensoryinnervation of the lowerlimb is by peripheralnerves on the posteriorabdominalandpelvic walls. •rami of spinal nerves L1 to L3 and part of L4. • The rest of the anterior ramus of L4 and the lumbosacral trunk, which enters the pelvic cavity and joins with the anterior rami of S1 to S3 and part of S4 to form the sacral plexus. Surgical Society | Junior Anatomy Series Major terminal branches • Femoral nerve EXTRA MATERIAL • Obturator nerve Other nerves include: • Lateral cutaneous nerve of the • Sciatic nerve thigh • Nerve to the obturator • Superior and inferior gluteal internus nerves • Nerve to the quadratus femoris • Posterior cutaneous nerve of the thigh • Perforating cutaneousnerve • Branches of the ilio-inguinal and genitofemoral nerves. Surgical Society | Junior Anatomy SeriesGateways to the lower limb Surgical Society | Junior Anatomy SeriesGateways to the lower limb Surgical Society | Junior Anatomy Series Femoral nerve • L2 to L4 anteriorrami • Passes through gap between the inguinal ligament and superior margin of the pelvis -> femoral triangle on the anteromedial aspect of the thigh (lateral to the femoral artery) • Motor innervation targets: • Anterior compartment of the thigh • Iliacus and pectineus muscles (from branches in the abdomen) • Sensory innervation targets: • Anterior aspect of the thigh • Anteromedial side of the knee • Medial side of the leg • Medial side of the foot Surgical Society | Junior Anatomy Series Obturator nerve • L2 to L4 anteriorrami • Descends along the posterior abdominal wall (following the arcuate line), passes through the pelvic cavity and enters the thigh by passing through the obturator canal • Has an anterior and posterior branch relative to the adductor brevis • Motor innervation targets: • Medial/Adductor compartment of the thigh (EXCEPT the part of the adductor magnus muscle that originates from the ischium and the pectineus muscle) • Obturator externus muscle • Sensory innervation targets: • Medial side of the upper thigh Surgical Society | Junior Anatomy Series Sciatic nerve • L4 to S3 • Leaves the pelvis through the greater sciatic foramen inferior to the piriformis muscle, enters and passes through the gluteal region and then enters the posterior compartment of the thigh where it divides into its two major branches: • common fibular nerve (L4 to L2 posterior divisions) • tibial nerve (L4 to S3 anterior divisions) • Motor innervation targets: • Posterior compartment of the thigh • Part of the adductor magnus originating from the ischium • All muscles in the leg and foot • Sensory innervation targets: • Lateral side of the leg and the lateral side and sole of the foot Surgical Society | Junior Anatomy Series Sciatic nerve • L4 to S3 • Leaves the pelvis through the greater sciatic foramen inferior to the piriformis muscle, enters and passes through the gluteal region and then enters the posterior compartment of the thigh where it divides into its two major branches: • common fibular nerve (L4 to L2 posterior divisions) • tibial nerve (L4 to S3 anterior divisions) • Motor innervation targets: • Posterior compartment of the thigh • Part of the adductor magnus originating from the ischium • All muscles in the leg and foot • Sensory innervation targets: • Lateral side of the leg and the lateral side and sole of the foot Surgical Society | Junior Anatomy Series Fibular nerve Course: • followsthe medialmarginof the bicepsfemoristendonover the lateralhead of the gastrocnemiusmuscleand towardthe fibula. • compartmentby passingbetweentheattachmentsof thehe lateral fibularis longusmuscletothe head and shaftof the fibula. • Here it divides intoits two terminalbranches: • superficialperoneal/fibularnerve • deep peroneal/fibularnerve Surgical Society | Junior Anatomy Series Fibular nerve Innervation targets: • The superficialfibularnerve descendsin the lateral compartmentand innervates the fibularislongus and fibularisbrevis. • It thenpenetratesdeepfascia in the lowerleg and entersthe footwhereit divides intomedial and lateral branches,which supplydorsalareasof the foot and toes exceptfor: • the web space betweenthe great and second toes,which is suppliedby the deep fibularnerve • the lateralside of the littletoe, whichis suppliedby the sural branchof the tibial nerve. • The deep fibularnerve passesanteromediallythroughthe intermuscularseptumintothe anteriorcompartmentof the leg, whichit supplies. Surgical Society | Junior Anatomy Series Tibial nerve Course: • passesunderthe tendinousarchformedbetweenthe fibularand tibial heads of thesoleus muscle • passesverticallythroughthedeep regionof the posteriorcompartmentof the leg on the surfaceof the tibialis posteriormusclewiththe posteriortibial • passesthroughthe tarsaltunnelbehindthe medialmalleolusto enterthe footand supplymostintrinsicmuscles(notEDB)and skin. • divides intoa medialand lateral plantarnerve(roughlyat the level of the sustentaculumtali) Surgical Society | Junior Anatomy SeriesTibial nerve In the leg, gives rise to: • branches that supplyall posteriorcompartmentmuscles • the sural nerve and medialcalcanealnerve (cutaneousnerves); - The sural nerve originateshigh in the leg betweentwoheads of gastrocnemius and suppliestheskinon the lowerposterolateralsurfaceof the leg and the lateralside of the footand littletoe. - The medialcalcanealnerve innervatesskinon themedial surfaceand sole of theheel Surgical Society | Junior Anatomy Series Femoral and obturator nerve injury Injuryto the femoralNerve: • Relativelysuperficial • Rarely damagedexceptby iatrogenicinjuries • Hip replacements+ laparoscopicrepairof inguinalhernias • Femoralartery/veincannulation Injuryto the obturatornerve: • Rarely damaged • Pain in its cutaneousdistribution=> malignantdiseasein the pelvis. Surgical Society | Junior Anatomy Series Sciatic and gluteal nerve injury Injuryto the sciaticnerve: • Injuryduringhip replacement= mostcommon • Othercauses= trauma(e.g. hip dislocationsor acetabularfractures)and pelvic disease. • Commonperoneal/fibulardivisionmorevulnerablethanthe tibial division Injuryto the commonperonealnerve: • Highly vulnerableto damageat the level of the fibularneck,aroundwhichthe nerve winds. • Causes of damageare trauma,kneereplacementand externalpressuree.g. from plasters or during surgicalprocedures. Injuryto the tibial nerve: • Nerve is very deep so rarely damagedin isolation. Injuryto the superiorglutealnerve: • Damage=> Trendelenburggait • Injuryduringhip replacement= mostcommon Surgical Society | Junior Anatomy Series Assessing lower limb innervation Innervationof the lowerlimb can be assessedeither; • Segmentally(i.e.prolapsedintervertebraldisc causingpressureon nerve root => segmentaleffects) • Regionally,via the PeripheralNerves (i.e.damageto a particularnervebranch=> peripheralloss) Nerve functioncan be assessedvia the followingmodalities; • Sensoryfunction • Reflexfunction • Autonomic function(thesympatheticsupplyto the lowerlimbs is via the T11-L2 portionof the thoraco-lumbaroutflow,no PNS) • Trophic Function(= effecton surroundingtissuesdue to chronic loss of innervation) When therehas been an injuryor disorderto a nerve, always describethe functionaldeficitin terms of theabove five functions. Surgical Society | Junior Anatomy Series T esting motor function - T one • To assesstone,assessthe musclegroupsat the hip, kneeand ankle joints,comparingeachside like for like. • Ensurethe patientis relaxed,placeyour hands on theirknee and roll the leg suchthatthereis rotationat the hip. Repeat with the otherleg. • Lift each kneebrisklyat least30cmoffthe bed and thenrelease - the kneeshoulddropand the leg straighten.If the foot also comesoffthe bed with the knee,thenthis indicateshypertonia. • Fflexedin thatposition.If thereare greaterthan5 involuntarycontractions(beats)of the gastrocnemiusmuscle,thenthaty may be a sign of an uppermotorneuronelesion. Surgical Society | Junior Anatomy Series T esting motor function - Power Hip: • Ask the patientto raise one of their legs whilstkeepingthe knee extended. • Testflexion(L2-3,femoralnerve) and extension(L4-5,inferiorgluteal nerve and sciaticnerve)at the hip jointby applyinga downwardsand upwardsforce,whileaskingthe patienttoresist. • Do the same withthe otherleg. Knee: • Flexthe patient'skneeto a 90° angle whilstkeepingthefoot flat on the bed. • Testextension(L3-4,femoralnerve)and flexion(L5,S1,sciaticnerve)by askingthepatientto kickout and pull their leg in, againstresistance. Ankle: • Testankledorsiflexion(L4-5, deepfibular nerve)and plantarflexion (S1,2,tibial nerve)by askingthepatientto resistan upwardand downwardmovement. Surgical Society | Junior Anatomy Series T esting motor function - Reflexes Patellarreflex(L3-4):Takethe weightof theleg and ask the patientto relax.Tap the patellartendon,whichis superiorto the tibial tuberosityand inferiorto the patella. Calcanealreflex(S1-2):Bend the kneeat 90° and with one hand,dorsiflextheankle joint.Ask the patientto relaxand tap the calcanealtendonon the posterioraspectof the ankle. Plantarreflex(L5,S1-2):Run an orangestickup the lateral soleof the footin the directionof thebig toe.As you approachthe base of the toes run the stickmedially.Thetoes shouldplantarflexin normalcircumstances.If theydorsiflex,thenthe patient is Babinskisign positive. Surgical Society | Junior Anatomy SeriesT esting sensory function • Sensationshouldbe assessedin the distributionof the dermatomes(area of skinwhichis suppliedby a singlespinalnerve root). • Areas of skinon lowerlimb with a singledermatomeonly (whichshould b• L1 - On the anteriorsurfaceof the proximalthigh. • L2 - On the anteriorsurfaceof the middleof the thigh,15-20cmabove the knee. • L3 - On the anteriorsurfaceof the knee. • L4 - On the anteromedialsurfaceof themiddleof the leg, 15-20cm belowthe knee. • L5 - On the dorsumof the footat the thirdmetatarsophalangealjoint. • S1 - On the mostlateral and distalaspectof the soleof the foot,at the base of the littletoe. REVISION TIP L3 to the knee L4 to the floor Surgical Society | Junior Anatomy Series Arterial circulation • Major artery supplyingthelower limb = femoral artery • Othe superiorand inferiorglutealarteriesand thelude obturatorartery Surgical Society | Junior Anatomy Series Femoral artery Course: • begins as the externaliliac artery • passesunderthe inguinalligamentto enterthe femoraltriangleon the anterior aspectof the upper thigh • passesverticallythroughthefemoral triangleand thencontinuesdownthe thigh in the adductorcanal. • leaves the canalby passingthroughthe adductorhiatusin the adductormagnus muscleand becomesthe poplitealarterybehindthe knee. KEY POINT The femoral artery is palpablein the femoral trianglejust inferiortothe inguinalligament midwaybetween the anteriorsuperioriliac spine and the pubic symphysis. Surgical Society | Junior Anatomy Series Femoral artery branches • Largestbranch= profundafemoris • Ofemoraltrianglehe lateralside of the femoralartery in the • Hthreeperforatingbranches.cumflexfemoralbranchesand Surgical Society | Junior Anatomy SeriesFemoral artery branches 4 branchesoriginatingin the femoraltrianglesupplyingcutaneousregions of theupper thigh,lowerabdomen,and perineum: • Superficialepigastricartery • Superficialcircumflexiliac artery • Superficialexternalpudendalartery • Deepexternalpudendalartery Surgical Society | Junior Anatomy Series Obturator artery Course: • Originatesas a branchof the internaliliac artery in the pelvic cavity and entersthe medialcompartmentof the thighthroughtheobturatorcanal • Bifurcatesintoan anteriorbranchand a posteriorbranch, whichtogetherforma channelthatcirclesthe marginof the obturatormembraneand lies withinthe attachmentof the obturatorexternusmuscle • Suppliesadjacentmuscles • Anacetabular vessel originates from theposteriorbranch, enters the hip jointthrough the acetabular notch,and contributesto thesupply of the head of the femur. Surgical Society | Junior Anatomy Series Popliteal Artery Course and branches: • Passesintothe posteriorcompartmentbetweenthegastrocnemiusand popliteus muscles. • Passesunderthe tendinousarchformedbetweenthe fibularand tibial heads of the soleusmuscle • Entersthe deepposteriorcompartmentof the leg whereit immediatelydivides into an anteriortibialarteryand a posteriortibialartery. • Twolarge sural arteries,oneon each side,branchfrom thepoplitealarteryto supply the gastrocnemius,soleus,and plantarismuscles (superficialposterior compartment). KEY POINT The popliteal artery is the deepest of the neurovascular structures in the popliteal fossa and is therefore difficult to palpate; however,a pulse can usually be detected bydeep palpation near the midline. Surgical Society | Junior Anatomy Series Arterial Supply to the Knee Joint Predominantlythrough: • dpopliteal,and lateralcircumflexfemoralarteriesin the thigh • the circumflexperoneal/fibularartery • recurrentbranches from the anteriortibial artery in the leg. => Thesevesselsform an anastomoticnetworkaroundthe joint. Surgical Society | Junior Anatomy Series Anterior Tibial Artery The anteriortibial arterydescendsthrough(and supplies)the anteriorcompartmenton the interosseousmembrane. Course(distal): • passesbetweenthe tendonsof the tibialis anteriorand extensorhallucislongusmuscles. • passesanteriorto the anklejointand continuesontothe dorsal aspectof the footas the dorsalis pedis artery. • gives offan anteriormedialmalleolarartery and an anteriorlateralmalleolarartery,whichpass posteriorly aroundthe distalends of the tibia and fibula,respectively, and connectwith vessels fromthe posteriortibialand fibulararteries toform an anastomoticnetworkaroundthe ankle. Surgical Society | Junior Anatomy Series Posterior Tibial Artery Courseand supply: • descendson the superficialsurfacesof the tibialis posteriorand flexor digitorumlongus muscles. • suppliestheposteriorand lateral compartmentsof the leg. Major branches: • Circumflexfibularartery (helpsformanastomoticnetworkof knee • Peroneal/fibularartery(descendsalong the lateralside of the posterior compartmentadjacentto the medial posteriorsurfaceof the fibulabetween the tibialis posteriorand flexorhallucislongusmuscles) o Alsohas branchesthatpass laterally throughthe intermuscularseptumto supplythe lateralcompartmentmuscles. • A perforatingbranch from the peroneal/fibularartery passesanteriorly throughtheinferioraperturein the interosseousmembraneto anastomose with a branchof the anteriortibialartery. Surgical Society | Junior Anatomy SeriesEntry of tibial arteries in the foot and their respective pulses ATA: • Entersdorsumof foot underextensorretinaculumas the dorsalis pedis artery • Here it is palpablebetweenthe firstand second metatarsals PTA: • Enterssoleof footthroughthe tarsaltunnel(runs behindthe medialmalleoluswhereit caneasily be palpated) • Divides intomedialand lateralplantararteriesto supplyfoot Surgical Society | Junior Anatomy Series Superficial and deep drainage of the lower limb • Tnames (femoral,superiorgluteal,inferiorgluteal,and similar obturator). • The majordeep vein drainingthe limb = femoral vein. It becomestheexternaliliacvein when it passesunderthe inguinalligamenttoenterthe abdomen. • The superficialveins are in the subcutaneousconnective tissueand are interconnectedwithand ultimatelydrain into the deep veins. • The superficialveins form twomajorchannelsboth originatingfroma dorsalvenous archin the foot – the great saphenousveinand the smallsaphenousvein. Surgical Society | Junior Anatomy Series Femoral vein The greatsaphenous(superficial),deep femoral (venae intothe femoralvein.ndafemoris)and poplitealveins drain Course: • Runs from poplitealfossathroughadductorcanal,over the adductormagnus,throughthe femoralcanal and underthe inguinalligamenttodrain intothe externaliliac vein. Surgical Society | Junior Anatomy Series Great and small saphenous veins Great SaphenousVein Origin: Medial Side of DorsalVenous Arch Ascent: • Anteriorto Medial Malleolus • Medial side of leg, kneeand thigh Drainageinto: • Femoralvein justinferiorto inguinalligament SmallSaphenousVein Origin: Lateral Sideof DorsalVenous Arch Ascent: • Passesbehindthelateral malleolus • Posteriorsurfaceof leg Drainageinto: • Penetratesdeep fasciato jointhe poplitealvein posteriortoknee Surgical Society | Junior Anatomy Series Femoral artery and vein cannulation • The femoralartery and vein canbe easily exposedand cannulatedat the femoral trianglee.g. for cardiac arteriography(artery)or for resuscitation(vein). • In a shockedpatientfor example,venous cannulationmay not be easy or possible. • The anatomicalsurfacemarkingof the long saphenousvein at theankle (2cmaboveand proximalto the tip of the “cut-down”.olus)makesit an excellentsiteto performa • A smallincisioncan be madeat the ankleand a venous cannulaplacedunderdirectvisionintothe vein for resuscitation. Surgical Society | Junior Anatomy Series Lymphatic drainage • Mostlymphaticvesselsin the lowerlimb drain into superficialand deep inguinalnodes locatedin the fasciajustinferiortothe inguinalligament. • Deepinguinal nodesinterconnectwiththe superficial inguinalnodes and drain intothe externaliliacnodes via vessels thatpass alongthe medial sideof the femoralvein as it passesunderthe inguinalligamentin the femoralcanal. • Superficialinguinalnodes receivelymph fromthe glutealregion,lowerabdominalwall,perineum,and superficialregionsof the lowerlimb. • Deepinguinal nodesreceivelymphfrom deep lymphaticsassociatedwith thefemoral vessels and perineum. Surgical Society | Junior Anatomy Series Borders and contents of the femoral triangle Femoraltriangleborders • Base of the triangle(superiorborderof triangle)= Inguinal ligament • Medial borderof triangle= Adductorlongus • Lateral borderof triangle= Sartorius • Apexof the triangle(inferiorend)= Continuouswith the adductorcanal Femoraltrianglecontents(withinfemoralsheath): • Femoralartery • Femoralvein • Lymphatics *Notethatthefemoral nerve is outsidethe femoralsheath Surgical Society | Junior Anatomy Series Borders and contents of the adductor canal Adductorcanal borders: • Anteriorborder= Sartorius • Posteriorborder= Adductorlongusand magnus • Lateral border= Vastus medialis Adductorcanal contents: • Femoralvein • Femoralartery • Saphenousnerve *Notethattheadductorcanalends at the adductorhiatusof the adductormagnus. It is here that: - The femoralartery becomesthepopliteal artery - The poplitealvein becomesthe femoralvein Surgical Society | Junior Anatomy Series [SBAs] PRACTICE QUESTION PRACTICE QUESTION PRACTICE QUESTION 1.Structures passingthrough the 2.Which muscle has dual nerve 3.Boundaries of femoral triangle does adductor hiatus include: supply NOT include: A. Saphenous nerve A. Sartorius A. Inguinalligament B. Profunda femoris B. Vastuslateralis B. Medial border of sartorius C. Both C. Adductor magnus C. Lateral border of adductor D. Neither D. Rectusfemoris longus E. Adductor longus D. All of the above E. None of the above Surgical Society | Junior Anatomy SeriesSurgical Society | Junior Anatomy Series Anas Aboukoura JAS LEADS Contact aka2818@ic.ac.uk Phase 1a: Anya Nanchahal (sn1119) Phase 1b: Andrea Perez Navarro (ap6618) CPA Lead: Defne Artun (da1019) Please fill out the following feedback form on Feedback Medall in order to receive a copy of the slides along Form with bonus SBAs to aid your revision! We hope you enjoyed this lecture and we'llsee you next Tueday for our final JAS Phase 1b Lecture of the yearon the musculoskeletalsystem!