The Lower Limb

Pelvis, Thigh, Legand Foot

Surface Anatomy

Surface AnatomyGluteal region / posterior pelvis

Iliac crestGluteus maximus

Cheeks

Natal/gluteal cleft Vertical midline; “Crack”

Gluteal folds Bottom of cheek; “prominence”

Surface Anatomy

Anterior thigh and legPalpate

PatellaCondyles of femur

Femoral TriangleBoundaries:

Sartorius (lateral)Adductor longus (medial)Inguinal ligament (superior)

Contents:Femoral artery, vein and nerve, lymph nodes

Surface AnatomyPosterior leg

Popliteal fossaDiamond-shape fossabehind kneeBoundaries

Biceps femoris(superior-lateral)Semitendinosis and semimembranosis(superior-medial)Gastrocnemius heads (inferior)

ContentsPopliteal artery and vein

Calcaneal (Achilles) tendon

Surface Anatomy

Anterior leg bonesTibia

Tibial tuberosityAnterior crestMedial surfaceMedial malleolus

FibulaLateral malleolus

Skeletal Composition

Bones of the Lower LimbFunction:

LocomotionCarry weight of entire erect bodySupportPoints for muscular attachments

Components:Thigh

FemurKnee

PatellaLeg

Tibia (medial)Fibula (lateral)

FootTarsals (7)Metatarsals (5)Phalanges (14)

Thigh

FemurLargest, longest, strongest bone in the body!!Receives a lot of stressCourses medially

More in women!Articulates with acetabulum proximallyArticulates with tibia and patella distally

KneePatella

Triangular sesamoidboneProtects knee jointImproves leverage of thigh muscles acting across the kneeContained within patellar ligament

LegTibia

Receives the weight of body from femur and transmits to footSecond to femur in size and weightArticulates with fibula proximally and distally

Interosseous membrane

FibulaDoes NOT bear weightMuscle attachmentNot part of knee jointStabilize ankle joint

Foot Function:Supports the weight of the bodyAct as a lever to propel the body forward

Parts:Tarsals

Talus = ankleBetween tibia and fibulaArticulates with both

Calcaneus = heelAttachment for CalcanealtendonCarries talus

NavicularCuboidMedial, lateral and intermediate cuneiforms

MetatarsalsPhalanges

Foot

3 archesMedialLateralTransverse

Has tendons that run inferior to foot bones

Help support arches of foot

FunctionRecoil after stepping

Longitudinal

Joints of Lower Limb

Hip (femur + acetabulum)Ball + socketMultiaxialSynovial

Knee (femur + tibia)Hinge (modified)BiaxialSynovialContains menisci, bursa, many ligaments

Knee (femur + patella)Plane Gliding of patellaSynovial

Joints of Lower Limb

Proximal Tibia + FibulaPlane, GlidingSynovial

Distal Tibia + FibulaSlight “give” (synarthrosis)Fibrous (syndesmosis)

Ankle (Tibia/Fibula + Talus)Hinge, UniaxialSynovial

Intertarsal & Tarsal-metatarsalPlane, synovial

Metatarsal-phalangesCondyloid, synovial

InterphalangealHinge, uniaxial

Muscles

Muscles of Hip and ThighGluteals

Posterior pelvisExtend thighRotate thighAbducts thigh

Anterior Compartment ThighFlexes thigh at hipExtends leg at knee

Medial/Adductor Compartment

Adducts thighMedially rotates thigh

Posterior Compartment Thigh

Extends thighFlexes leg

GlutealsGluteus maximus

Origin - Ilium, sacrum and coccyxInsertion - Gluteal tuberosity of femur, iliotibial tractAction - Extends thigh, some lateral rotation and abductionInnervation - Inferior gluteal nerve

Gluteus mediusGluteus minimus

Origin - Ilium Insertion - Greater trochanter of femur Action - Abduction, medial rotationInnervation - Superior gluteal nerve

Lesser Gluteals help stabilize hip to allow fluent bipedal walking

Posterior PelvisTensor fasciae latae

Origin – iliac crest and anterior inferior iliac spineInsertion – iliotibial tractAction - Flex thigh, abduct thigh, medial rotation of thighInnervation – Superior gluteal nerve

Anterior Compartment ThighQuadriceps femoris

Rectus femorisOrigin – anterior inferior iliac spine, margin of acetabulumInsertion – patella and tibialtuberosity via the patellar ligament Action – extends knee, flexes thigh

Vastus lateralisVastus medialisVastus intermedius

Origin - femurInsertion – patella and tibialtuberosity via the patellar ligamentAction – extends knee

SartoriusOrigin - anterior superior iliac spineInsertion – medial tibiaAction - flex, abduct, lat rotate thigh; weak knee flexorAll above innervated by the femoral nerve!!!

Anterior Compartment Thigh

IliopsoasOrigin - Ilia, sacrum, lumbar vertebraeInsertion – lesser trochanterAction – flexor of thighInnervation – femoral nerve

AdductorsAdductor longusAdductor brevisAdductor magnus

Origin – inferior pelvisInsertion - femurAction – adducts and medial rotatesInnervation – Obturator nerve

PectineusOrigin - pubisInsertion – lesser trochanterAction – adducts, medial rotatesInnervation – femoral, sometimes obturator

GracilisOrigin - pubisInsertion – medial tibiaAction – adducts thigh, flex, medial, rotates legInnervation – Obturator nerve

Posterior Compartment - HamstringBiceps femoris (2 heads)

Origin – ischial tuberosity, distal femurInsertion - lateral tibia, head fibulaAction - thigh extension, knee flexion, lateral rotation

SemitendinosusSemimembranosus

Origin - ischial tuberosityInsertion - medial tibiaAction - thigh extension, knee flexion, medial rotation

Sciatic nerve innervates all of the above muscles!!!

Muscles of the Leg

Anterior CompartmentDorsiflex ankle, invert foot, extend toesInnervation: Deep fibular nerve

Lateral CompartmentPlantarflex, evert footInnervation: Superficial Fibular nerve

Posterior Compartment Superficial and deep layersPlantarflex foot, flex toesInnervation: Tibial nerve

Anterior CompartmentTibialis anterior

Origin - tibiaInsertion - tarsalsAction - dorsiflexion, foot inversion

Extensor digitorum longusOrigin – tibia and fibulaInsertion - phalangesAction – toe extension

Extensor hallucis longusOrigin – fibula, interosseousmembraneInsertion – big toeAction - extend big toe, dorsiflexfoot

All innervated by deep fibular nerve

Lateral CompartmentFibularis (peroneus) longus

Origin – lateral fibulaInsertion – 5th metatarsal, tarsalAction - plantarflex, evertfoot

Fibularis (peroneus) brevisOrigin – distal fibulaInsertion - proximal fifth metatarsalAction – same as above!!

All innervated by the superficial fibular nerve

Superficial Posterior CompartmentTriceps surae

Gastrocnemius (2 heads)Origin - medial and lateral condyles of femurInsertion - posterior calcaneus via Achilles tendon

SoleusOrigin – tibia and fibulaInsertion – same as above

Action of both – plantarflex foot

Plantaris (variable)Origin – posterior femurInsertion – same as above!Action – plantarflex foot, week knee flexionAll innervated by the tibial nerve

Deep Posterior CompartmentPopliteus

Origin - lateral condyle femur and lateral meniscusInsertion – proximal tibiaAction – flex and medially rotate leg

Flexor digitorum longusOrigin - tibiaInsertion - distal phalanges of toe 2-5 Action – plantarflex and invert foot, flex toe

Flexor hallucis longusOrigin - fibulaInsertion - distal phalanx of halluxAction - plantarflex and invert foot, flex toe

Tibialis posteriorOrigin – tibia, fibula, and interosseousmembraneInsertion - tarsals and metatarsalsAction - plantarflex and invert foot

All innervated by the tibial nerve

Innervation

Plexuses of the Lower Limb“Lumbosacral plexus”Lumbar Plexus

Arises from L1-L4Lies within the psoas major muscleMostly anterior structures

Sacral PlexusArises from spinal nerve L4-S4Lies caudal to the lumbar plexusMostly posterior structures

Lumbar PlexusFemoral nerve

Cutaneous branchesThigh, leg, foot (e.g. saphenous nerve)

Motor branchesAnterior thigh muscles (e.g. quadriceps, sartorius, iliopsoas)

Obturator nerveSensory

Skin medial thigh; hip, knee jointsMotor

Adductor musclesLateral femoral cutaneous

SensorySkin lateral thigh

GenitofemoralSensory

Skin scrotum, labia major, anterior thighMotor

Cremaster muscle

Sacral PlexusSciatic

Motor:Hamstring

Branches into:Tibial nerve

CutaneousPosterior leg and sole of foot

MotorPosterior leg, foot

Common fibular (peroneal) nerveCutaneous

Anterior and lateral leg, dorsum footMotor

Lateral compartment, tibialis anterior, toe extensors

Superior gluteal nerveMotor

Gluteus medius and minimus, tensor fasciae latae

Sacral Plexus (continued)

Inferior gluteal nerveMotor

Gluteus maximus

Posterior femoral cutaneous nerve

SensoryInferior buttocks, posterior thigh, popliteal fossa

Pudendal nerveSensory

External genitalia, anusMotor

Muscles of perineum

Vasculature

Arteries

Common iliac (from aorta) branches into:

Internal iliacSupplies pelvic organs

External iliacSupplies lower limb

Arteries

Internal iliac branches into:Cranial and Caudal Gluteals

(Superior and Inferior)Gluteals

Internal PudendalPerineum, external genitalia

ObturatorAdductor muscles

Other branches supply rectum, bladder, uterus, vagina, male reproductive glands

ArteriesExternal iliac becomes…….

FemoralOnce passes the inguinal ligamentLower limbBranches into Deep femoral

Adductors, hamstrings, quadricepsBranches into Medial/lateral femoral circumflex

Head and neck of femur

Femoral becomes……Popliteal (continuation of femoral)

Branches into:Geniculars

KneeSplits into:

Anterior TibialAnterior leg muscles, further branches to feet

Posterior TibialFlexor muscles, plantar arch, branches to toes

Veins Deep Veins: Mostly share names of arteries

Ultimately empty into Inferior Vena Cava

PlantarTibialFibularPoplitealFemoralExternal/internal iliacCommon iliac

Superficial Veins Dorsal venous arch (foot)Great saphenous (empties into femoral)Small saphenous (empties into popliteal)