54 Neurovasculature

STUDYAIMS

At the end of your study, you should be able to:

Describe the arterial supplyof the lower limb, distinguishing the arteries supplying each of the compartments of the thigh and leg

Know the surface markings to locate the femoral arteryand palpate the pulses of the popliteal, posterior tibial, and dorsalis pedis arteries Describe the venous drainage of the lower limb

Describe the lymphatic drainage of the lower limb

Know the nervous innervation to the compartments of the thigh and leg and recognize the course of the major nerves of the lower limb Understand the dermatome and myotome maps of the lower limb

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GUIDE

Lower Limb: Neurovasculature

Vascular Supply: Arteries

[Plate 490, Arteries and Nerves of Thigh: Posterior View]

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[Plate 500, Arteries of Thigh and Knee: Schema]

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Femoral artery

Continuation of the external iliac artery

Main arteryof lower limb

Palpable inferior to the midinguinal point, not at the midpoint of the inguinal ligament

Descends in femoral triangle on iliopsoas and pectineus, lateral to femoral vein

Enters adductor canal deep to sartorius and exits at adductor hiatus Profunda femoris (deep arteryof thigh)

Main arteryto the thigh

Largest branch of femoral

Arises from lateral aspect of femoral in femoral triangle

Supplies anterior and medial (adductor) compartments of the thigh

Supplies posterior compartment byperforating arteries

Gives off medial and lateral circumflexfemoral arteries that supplythe head of the femur and muscles of lateral thigh Obturator artery

Branch of the internal iliac artery(or may arise from the inferior epigastric)

Enters thigh through obturator foramen

Divides into anterior and posterior branches

Supplies adductor compartment of the thigh along with profunda femoris Popliteal artery

Continuation of the femoral artery(at adductor hiatus)

Palpable in the popliteal fossa (best felt when knee is flexed)

Gives off five genicular branches supplying articular capsule and ligaments of knee joint

Medial and lateral superior genicular

Middle genicular

Medial and lateral inferior genicular

Form anastomosis around knee joint

Bifurcates into anterior and posterior tibial arteries Anterior tibial artery

Smaller of two terminal branches of popliteal Passes through gap in interosseous membrane

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Supplies muscles of anterior compartment of the leg

Descends on interosseous membrane and becomes dorsalis pedis artery

Posterior tibial artery

Larger of two terminal branches of popliteal

Supplies muscles of posterior compartment

Gives off fibular artery

Descends deep to soleus

Provides main blood supplyto foot, after passing inferior to medial malleolus

Palpable behind the medial malleolus

Gives off nutrient arteryto the tibia

Circumflexfibular artery

Arises from origin of anterior or posterior tibial

Passes over neck of fibula to anastomosis around knee

Fibular artery

Largest branch of posterior tibial

Supplies muscles of lateral compartment of the leg

Begins below tendinous arch of soleus

Gives off nutrient arteryto the fibula

Pierces interosseous membrane to reach dorsum of foot

Dorsalis pedis

Continuation of the anterior tibial artery

Palpable between the first and second metatarsal heads

Divides into plantar and arcuate arteries

Supplies muscles on dorsum of foot

Pierces first dorsal interosseous muscle as deep plantar arteryof foot (plantar arterial arch)

Medial plantar artery

Smaller of two terminal branches of posterior tibial artery

Supplies muscles of great toe, skin on medial side of sole

Gives off plantar digital arteries

Lateral plantar artery

Larger than medial

Accompanies lateral plantar nerve

Arches mediallyacross foot, beginning at base of fifth metatarsal as deep plantar arch

Gives off four plantar metatarsal arteries

Joins branches of medial plantar to form plantar digital arteries to toes

Vascular Supply: Veins

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Lower limb has superficial and deep venous systems with perforating veins communicating between them

Veins have valves

Veins of foot

Superficial

Metatarsal veins merge to form dorsal venous arch

Communicates with plantar arch

Both drain mediallyto great saphenous vein and laterallyto small saphenous vein

Deep

Begin as dorsal digital and plantar digital veins

Merge to deep veins accompanying arteries in leg and thigh

Superficial veins of leg and thigh

Great saphenous vein

Courses along medial side of dorsum of the foot

Passes in front of medial malleolus (location for venous cut down for emergency IV access here)

Anastomoses freelywith small saphenous vein

Ascends medial side of leg, then posterior to the knee

Ascends along medial thigh to saphenous hiatus in fascia lata

Traverses hiatus to emptyinto femoral vein

Has manyvalves

Small saphenous vein

Runs behind the lateral malleolus

Ascends along lateral border of calcaneal tendon

Pierces the deep fascia

Ascends between heads of gastrocnemius

Empties into popliteal vein

Accompanied bythe sural nerve

Deep veins of leg and thigh

Accompanyall major arteries (venae comitantes)

Are usuallypaired

Are variable and anastomose freely

Unite to form the popliteal vein and ascend as femoral vein

Perforating veins

Penetrate deep fascia

Connect superficial and deep veins

Have valves

Lymphatics

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Superficial lymphatics follow the superficial veins

Lymphatics following the great saphenous drain into superficial inguinal nodes

Lymphatics following the small saphenous vein drain into popliteal nodes

Deep lymphatics

Follow vasculature in the muscle compartments

Drain to deep inguinal nodes

Popliteal nodes drain into the deep inguinal nodes

Nerves

[Plate 526, Femoral Nerve and Lateral Cutaneous Nerve of Thigh]

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[Plate 528, Sciatic Nerve and Posterior Femoral Cutaneous Nerve]

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Cutaneous nerves

Subcostal nerve (T12) to skin anterior to greater trochanter

Iliohypogastric nerve (L1) to superior lateral buttock

Ilioinguinal (L1) to proximal and medial thigh

Genitofemoral nerve (L2-L3) to immediatelyinferior to middle inguinal ligament

Lateral femoral cutaneous ((L2-L3) to lateral and anterior thigh

Femoral nerve (L2-L4)

Via anterior femoral cutaneous branches to anterior and medial thigh

Via saphenous nerve to medial side of leg and foot

Obturator nerve-branch to anterior, medial and posterior proximal thigh

Posterior femoral cutaneous nerve-to posterior thigh and popliteal region

Sciatic nerve

Supplies foot and most of leg

Via sural, common, superficial, and deep fibular nerves

Cluneal nerves (superior middle and inferior)-buttock

Nerves to muscles of lower limb from lumbosacral plexus

Nerves in the gluteal region

Superior gluteal nerve (L4-S1)

Emerges superior to piriformis

Supplies gluteus medius, gluteus minimus and tensor fasciae latae

Inferior gluteal nerve (L5-S2)

Inferior to piriformis

Supplies gluteus maximus

Nerve to quadratus femoris (L4-S1): also supplies inferior gemellus

Pudendal nerve (S2-S4): supplies the perineum (not structures in the gluteal region)

Nerve to obturator internus (L5-S2)

Nerves to anterior and lateral thigh

Femoral nerve (L2-L4)

Enters thigh lateral and deep to femoral artery

Supplies the anterior compartment of the thigh

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Obturator nerve (L2-L4)

Enters thigh through obturator foramen and divides into anterior and posterior branches

Supplies medial (adductor) compartment of thigh

Nerves of posterior thigh

Sciatic nerve (L5-S2)

Enters gluteal region from pelvis through greater sciatic foramen

Emerges inferior to the piriformis muscle

Supplies no structures in the gluteal region

Supplies posterior thigh muscles

Bifurcates in lower third of thigh into tibial and common fibular nerves

Via tibial and common fibular nerves, supplies all leg and foot muscles

Nerves of leg

Tibial nerve

Supplies the posterior compartment of leg

Ends bydividing into medial and lateral planter nerves

Common fibular nerve

Wraps around fibular head

Divides into deep and superficial peroneal nerves

Deep fibular nerve supplies anterior compartment of leg

Superficial fibular nerve supplies lateral compartment of leg

Nerves of foot

Medial plantar to 3½ muscles of plantar foot

Lateral plantar to remaining muscle of plantar foot

Dermatomes

Myotomes

Agroup of muscles supplied byfibers from a single spinal nerve or a discrete group of spinal nerves is called a myotome

Myotomes of the Lower Limb

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