Chapter 9 - Blood Vessels of the Lower Limb

What comprises the Cardiovascular system

The cardiovascular system consists of the heart and all blood vessels (arteries, veins, capillaries)

Artery - any vessel that carries blood away from the heart

–Arteries supply any structure that they go past

• Arterial patterns are moderately variable between different individuals

–Muscles can be supplied by more than one artery

• Large or long muscles usually supplied by several arteries

Know location of artery within body and surrounding structures that could be supplied by that artery*

Vein - any vessel that carries blood toward heart

–Veins have thinner walls compared to arteries - due to lower venous blood pressure

• Blood flows down pressure gradient - higher blood pressure in arteries

–Movement of blood in veins aided by contraction of adjacent muscles

• Bulging of contracted muscle squeezes veins; moves blood

• Particularly important in lower limb, where is blood must move against gravity

–Veins have one-way valves - prevent backflow of blood

• Varicose veins - due to weak valves that allow backflow; leads to pooling of blood, inflammation, and pain

–Venous patterns are highly variable between individuals

–Vein running with an artery has same name as artery

Capillary - microscopic vessels connecting arteries and veins

• Very thin walled

• Capillaries are the only vessels that allow for the exchange of nutrients and metabolic waste products between blood and cells of body

Describe the blood supply to limbs

Blood is pumped to body by left ventricle of heart

• Blood pumped into aorta (largest artery of body)

Aorta - divided into 3 regions:

–Ascending aorta - 1^st region

• Exits left ventricle and passes superiorly

• Located at mid-line of thorax, directly behind upper sternum

–Arch of aorta (aortic arch) - 2^nd region

• Makes U-turn - curves posteriorly and to left

• Gives off 3 arteries that supply head, neck, & upper limbs

–Descending aorta - 3^rd region

• Passes posterior to heart and runs inferiorly through thorax and abdomen

–Located against posterior body wall (immediately anterior to vertebral column)

• Subdivided into thoracic aorta and abdominal aorta

• Terminates in lower abdomen (at level of your umbilicus) - divides into right & left common iliac arteries

–Common iliac arteries supply the pelvis and lower limbs*

Describe blood supply to hip and thigh

Common iliac artery

–Terminal branch from abdominal aorta

• Runs inferiorly and laterally - descends into pelvic region

–Terminates by dividing into:

• External iliac artery

• Internal iliac artery

Internal iliac artery. Branches, exits, emerges, supplies

–Passes into true (lesser) pelvic cavity

–Gives off branches that supply pelvic organs

–Branches to posterior hip that exit pelvis:

Superior gluteal artery (runs with superior gluteal n.)

• Exits via greater sciatic foramen

• Emerges at superior margin of piriformis muscle

• Supplies mm. gluteus medius, gluteus minimus, and tensor fasciae latae

Inferior gluteal artery (runs with inferior gluteal n.)

• Exits via greater sciatic foramen

• Emerges at inferior margin of piriformis muscle

• Supplies m. gluteus maximus

–Internal iliac artery sends one branch to the thigh:

Obturator artery (runs with obturator n.)

• Exits via obturator foramen

• Passes into medial thigh

• Supplies obturator externus and proximal ends of medial thigh muscles

External iliac artery

–Runs along pelvic brim

–Exits pelvis by passing under inguinal ligament - enters anterior thigh

–At inguinal ligament, name of artery changes to femoral artery

• External iliac artery terminates at the inguinal ligament

• Femoral artery begins at inguinal ligamen

Femoral artery

–Femoral artery begins at inguinal ligament, then descends through thigh

–Proximal ⅓ of thigh - femoral artery is located within femoral triangle (with femoral nerve)

• Femoral triangle: inguinal ligament, m. sartorius, m. adductor longus

–Middle ⅓ of thigh - femoral artery located within adductor canal

–Adductor canal - groove located between m. quadriceps femoris and adductor muscles of medial thigh

• M. Sartorius forms roof of adductor canal (overlies femoral artery in middle ⅓ of thigh)

–Distal ⅓ of thigh - femoral artery passes through adductor hiatus (gap in insertion of adductor magnus muscle)

–Artery passes from thigh into popliteal fossa (behind knee)

• Name of artery changes to become popliteal artery

–Femoral artery thus terminates at adductor hiatus

• Popliteal artery begins at adductor hiatus

Describe and list the Branches of Femoral Artery

Only major branch given off by femoral artery within the thigh is the deep femoral artery

• This branch provides majority of blood supply to muscles of thigh

Note: obturator artery supplies proximal ends of medial thigh muscles

Deep femoral artery

Perforating arteries

medial & lateral circumflex femoral arteries

Deep femoral artery

–Branches from femoral artery within femoral triangle (in proximal thigh)

–Deep femoral artery dives deep and runs along medial side of femur

• Terminates by dividing into four perforating arteries

• Perforating arteries wrap around posterior, lateral, and anterior sides of femur

–Deep femoral artery (with perforating arteries) supply majority of blood for muscles of the thigh

Perforating arteries

Arteries must thus perforate (penetrate) through all muscles attaching to linea aspera of posterior femur:

•M. Vastus medialis

•M. Vastus lateralis

•M. Pectineus

•M. Adductor longus

•M. Adductor brevis

•Adductor part of m. adductor magnus

•Short head of m. biceps femoris

Perforating arteries also contribute to blood supply for mm. vastus intermedius & rectus femoris, plus all hamstring muscles of posterior thigh

Medial & lateral circumflex femoral arteries

In proximal thigh, deep femoral artery also gives off medial & lateral circumflex femoral arteries

–These wrap around proximal end of femur (circumflex = “to bend around”)

• Medial artery passes to medial side of proximal femur; lateral artery passes to anterior & lateral sides of femur

–Both supply muscles of the proximal thigh and muscles that attach to greater & lesser trochanters of femur

• Also provide blood supply to head & neck of femur and to hip joint

• “Broken hip” = fracture of femoral neck; damage to circumflex arteries can lead to poor healing or necrosis of femur

Popliteal Artery

Popliteal artery

–Begins at adductor hiatus

• Adductor hiatus - gap in attachment of adductor magnus muscle to femur

–Popliteal artery then descends through popliteal fossa

• Popliteal artery is deepest structure within popliteal fossa

• Tibial nerve is most superficial structure within popliteal fossa

–Begins at adductor hiatus - enters popliteal fossa

–Popliteal artery exits popliteal fossa and enters posterior leg

• Passes between medial/lateral heads of m. gastrocnemius, then dives under m. soleus

–Popliteal artery terminates in proximal leg by dividing into anterior tibial artery and posterior tibial artery

Anterior Tibial Artery

Anterior tibial artery - arises in posterior leg as terminal branch of popliteal artery

–Passes through interosseous membrane to enter anterior compartment of the leg

• Runs inferiorly - supplies all muscles of anterior leg compartment

–Continues across anterior ankle to dorsum of foot

• Supplies intrinsic muscles of dorsal foot (m. extensor hallucis brevis and m. extensor digitorum brevis)

Posterior Tibial Artery

Posterior tibial artery - arises in posterior leg as terminal branch of popliteal artery

–Posterior tibial artery runs inferiorly within deep posterior leg compartment

• Runs with tibial nerve

• Supplies all muscles of deep posterior leg compartment

–Gives off fibular artery - to muscles of lateral leg

–Crosses ankle by passing posterior to medial malleolus of tibia and enters plantar foot

• Supplies all intrinsic muscles of plantar foot

Structures at Medial Malleolus

Three muscles, an artery, and a nerve all pass posterior to medial malleolus of the tibia to enter the plantar foot

Use pneumonic “Tom, Dick, and Harry”

• T: tibialis posterior (1^st muscle tendon; located immediately posterior to medial malleolus)These structures are held in place by a retinaculum and have specific positions at the medial malleolus

• D: flexor digitorum longus (2^nd muscle tendon)

• an: posterior tibial artery and tibial nerve

• H: flexor hallucis longus (3^rd muscle tendon; located the most posteriorly from medial malleolus)

Superficial Veins of Lower Limb

Superficial veins run within the superficial fascia (superficial to deep investing fascia)

• Unaccompanied by arteries

• Connected to (can drain to) deep veins of the limb

Dorsal venous arch

• Formed by veins on dorsal side of foot - receive drainage from toes and foot

• Gives rise to great saphenous vein (from medial side of dorsal arch) and small saphenous vein (from lateral side of dorsal arch)

Great saphenous vein

• Begins on medial side of dorsal foot

• Runs up medial side of leg and thigh

—» Passes posterior to medial knee

• In proximal thigh (just inferior to inguinal ligament), vein dives deep (penetrates through fascia lata) and drains into femoral vein

Small saphenous vein

• Begins on lateral side of dorsal foot

• Runs up posterior leg

• Posterior to knee, dives through popliteal fascia to drain into popliteal vein