Blood Supply of Lower Limb

Compare vasculature of skin

• epidermis (epithelium) → avascular

• dermis → vascular

What vasculature travel through the greater and lesser sciatic foramen?

• Greater sciatic foramen

  • exit pelvis → superior and inferior gluteal av, pudendal av

• Lesser sciatic foramen

  • reenter pelvis → pudendal a.

What vasculature travels through the obturator foramen?

• through obturator canal of obturator membrane

  • obturator av

    • anterior and posterior obturator a. branches wrap around external opening

Lower limb blood supply branching (trunk → inguinal)

• Descending abdominal aorta gives off two →

  • Common iliac arteries, divides into →

    • Internal iliac artery →

      • Superior and inferior gluteal arteries

      • Obturator artery

    • External iliac artery →

      • passes deep to inguinal ligament →

        • femoral artery

Gluteal vessels (name, path/branching)

• Superior gluteal artery

  • exits pelvis superior to piriformis through greater sciatic foramen

    • divides into superficial (b/w gluteus max and med) and deep branches (b/w glut med and min)

• Inferior gluteal artery

  • exits pelvis inferior to piriformis through greater sciatic foramen

Obturator a. (path, branches)

• branches from internal iliac a. and exits pelvis through obturator canal of obturator membrane

  • right after leaving plevis, gives off

    • anterior branch

      • lines anterior/medial obturaor forman margin

    • posterior branch

      • lines posterior/lateral obturator foramen magirn

      • gives off acetabular branch (a. to the ligament of the head of the femur)

        • travel through acetabular notch

What are the branches of deep femoral a.?

•  medial circumflex femoral a → hip joint prominent blood supply

  • ascending branch

  • transverse branch

    • retinacular a.

• lateral circumflex femoral a → anastomosis a.

  • ascending branch

    • travels up to gluteal region

      • anastomosis with gluteal arteries

      • connects external and internal iliacs

  • transverse branch

    • wraps around femur

      • anastomosis with medial circumflex femoral a. before it dives into joint capsule

  • descending branch

    • runs to knee

      • anastomosis with superior lateral genicular a.

What do we name blood vessels by?

• based on where they end up not where they originate

Describe the vascular supply to the hip joint

• Medial circumflex femoral artery

  • circles the femur medially

    • ascending branch

    • transverse branch

  • supplies majority of blood supply to head and neck of femur

    • retinacular a. pass from the medial circumflex along the neck towards the head

• Lateral circumflex femoral artery (mainly anastomoses)

  • circles the femur laterally

    • ascending branch

    • descending branch

    • transverse → anastomosis with medial circumflex femoral a. before it divides into joint capsule

• Artery of the head of the femur

  • provides small amount of blood to head

Why are intracapsular femoral neck fractures a concern? (especially elderly individuals)

• Unlike the knee joint, for instance, that is highly anastomosed, the hip joint is described as having a “dead end” blood supply.

• This means if the main vessels are damaged or blocked, there is no alternative network of blood supply to sufficiently maintain the head and neck of the femur.

• Even if the artery of the head of the femur was still intact, it cannot supply an adequate amount of blood to sustain the bone.

• The dangers with femoral neck fractures, is that it can result in the laceration of the surrounding vascular structures.

• If the retinacular arteries are cut and not repaired quickly, the head of the femur will begin to undergo avascular necrosis.

• The combination of instability and potential osteoporosis in elderly patients makes them much more susceptible to falls and thus hip fractures.

• Due to their age and bone quality, they would likely need a hip replacement.

What vasculature supplies the posterior thigh?

• Inferior gluteal artery

• Medial circumflex femoral artery

• Deep femoral artery

  • deep artery of thigh/profunda artery and perforating artery

  • 1st, 2nd and 3rd perforating arteries

• Popliteal artery

  • after femoral triangle it travel through adductor canal, through adductor magnus muscle and exits through adductor hiatus

  • femoral artery has name change in back of knee

Popliteal artery branches

• Superior medial genicular artery

  • anastomoses superiorly with →

    • Descending genicular artery

• Superior lateral genicular artery

  • anastomoses superiorly with →

    • Descending branch of the lateral circumflex artery

• Middle genicular artery →

  • branches anteriorly from popliteal artery behind the knee to supply knee joint

• Inferior medial genicular artery

• Inferior lateral genicular artery

  • anastomoses inferiorly with →

    • Anterior tibial recurrent (from anterior leg)

Discuss anastomosis in context of the knee

• Tissues require oxygen to survive

• Anastomosis creates alternative vascular pathways, so that if one blood vessel is blocked, the tissue can still receive blood flow from a different source

• Pressure gradients allow for blood to shift directions through the network of vessel to continue supplying that area

• In the knee for example, if the popliteal artery is blocked, the surrounding genicular ateries can supply enough blood flow to maintain tissue viability, but not for long term function

• Similar to a “spare tire”, they can provide blood flow to keep the lower leg alive long enough to receive medical attention. In response to the decreased blood supply, the body would start producing pain signals as a warning.

Subcutaneous branching of femoral a.

• branch from femoral a. in femoral triangle and pierce through cribriform fascia at saphenous opening

  • superficial epigastric a. (ascending up abdominal wall)

  • superficial circumflex iliac (runs lateral to ilium)

  • superficial external pudendal a. (runs medial to perineum)

• same spot where greater saphenous v. pierces fascia to drain into femoral v.

Deep vessels branching originating from femoral a.

• deep external pudendal a.

  • deeper, also running medially to perineum

• deep femoral a (profunda femoris)

  • sits deep to femoral a

• descending genicular (knee)

  • gives off branch before becoming popliteal

• popliteal a

  • name change after adductor hiatus

Popliteal fossa - contents

• Deep → superficial

  • popliteal artery (deep)

  • popliteal vein (middle)

  • Tibial and common fibular nerve (superficial)

  • Small saphenous v (subcutaneous)

  • posterior cutaneous nerve of the thigh (subcutaneous)

Discuss the superficial veins of the lower extremity

• Dorsal venous arch (dorsal foot)

  • has two ends (medial and lateral)

  • Great saphenous vein

    • runs medially up leg and thigh → drains into femoral vein (through saphenous opening of cribriform fascia)

    • saphenous n. runs with it

  • Lesser saphenous vein

    • runs laterally up ankle to posterior leg → drains into popliteal vein

    • sural n. runs with it

  • Perforating veins

    • both great and lesser saphenous have vein branches that perforate through the deep fascia to deeper veins as they ascend up the leg

Why do we have an extra network of superficial veins with no arterial counterparts?

• Veins have to carry venous blood against gravity back to the heart. Arterials walls have much more smooth muscle compared to the thin walls of veins. To help compensate for this, veins carry smaller blood volumes across an additional network of superficial veins.

What happens if great saphenous is lost?

• There will be impaired superficial venous drainage, or venous congestion, resulting in the build up of excess fluid in surrounding tissues (edema).

Deep veins of the lower extremity

Basically, all of the named arteries but veins

• femoral v.

• deep femoral v.

• medial/lateral circumflex v.

• anterior tibial v.

• dorsal venous arch

• popliteal v.

• fibular v

• plantar arch

• posterior tibial v.

• common iliac v.

• internal iliac v

• external iliac v

• obturator v.

• genicular v.

• medial and lateral circumflex v.

• superior and inferior gluteal v

What do deep veins of the body use compensate for their weakened muscle wall?

• valves

  • prevent back flow of blood as they fight against gravity/internal pressure

• skeletal muscle

  • walking compresses the veins and helps push up blood back to heart

  • pressure on sole of foot during stance and toe off pushes venous blood out of foot into veins of calf

• sitting for long time → blood pooling → clots → stroke/heart attack/pulmonary embolism

Femoral triangle contents

• NAVL (lateral to medial)

  • femoral n

  • femoral a

  • femoral v

  • deep inguinal lymph nodes

    • passing through the femoral canal

What contributors to blood supply of the knee joint?

• middle genicular a. pierces the joint capsule to supply the cruciate ligaments, synovial membrane, peripheral aspect of menisci

Blood supply of the leg

• popliteal a exits popliteal fossa through → tendinous arch (soleus m.)

  • anterior tibial a.

    • passes through opening in interosseous membrane to enter anterior leg

      • runs lateral to tibialis anterior muscle belly and tendon

    • after it crosses ankle joint on dorsum →

      • dorsalis pedis a.

  • posterior tibial a.

    • runs parallel to tibial n within posterior leg

      • gives off fibular a.

        • supplies lateral leg compartment through perforating branches (but stays in posterior leg)

    • travels through tarsal tunnel at medial ankle to plantar surface of foot

What vasculature runs through the tarsal tunnel?

• posterior tibial a.

  • splits into medial and lateral plantar a.

What provides blood supply to the ankle joint?

• fibular a.

• anterior tibial a.

• posterior tibial a.

Arterial supply for plantar foot

Posterior tibial a (enters foot via tarsal tunnel)

• Medial Plantar a. (smaller branch)

  • runs between abductor hallucis and flexor digitorum brevis (b/w layers 1 + 2)

  • gives off media plantar digital a. to hallux

• Lateral Plantar a. (larger branch)

  • runs across quadratus plantae and deep to flexor digitorum brevis towards 5th metatarsal (b/w layers 1 + 2)

  • At 5th metatarsal, dives deep to interossei/metatarsal surface and runs medially (b/w layers 3 + 4) to form the →

    • Deep Plantar Arch

      • arches medially across bases of metatarsals 2-4

      • dives into plantar surface of 1st doral interosseous m. to anastomose with terminal branch of dorsalis pedis a (Deep Plantar a.)

      • off of arch →

        • Perforating Branches

          • dive through intermetatarsal spaces to anastomose with dorsal metatarsal a.

        • Plantar Metatarsal a.

          • run superficial to plantar interossei m. (spaces 2-4) and 1st dorsal interosseous m.

          • Give off →

            • Plantar Digital a. (supply adjacent sides of digits 1-5)

Arterial supply of the dorsal foot

Anterior tibial a. crosses ankle joint (name change)

• Dorsalis pedis (travels straight forward along dorsum to first intermetatarsal space), along the way gives off

  • Medial and Lateral tarsal a.

    • small branches at proximal ankle

  • Arcuate a. (branches laterally near metatarsal bases, arches across bases of metatarsals 2-4)

    • → 2-4th dorsal metatarsal a. (run superficial to dorsal interossei)

      • → Dorsal digital a. (supply adjacent sides of digits 2-5 + lateral border of digit 5)

    
    

• Terminal divisions of Dorsalis pedis a. (at proximal 1st intermetatarsal space

  • 1. Deep plantar a

    • dives between two heads of 1st dorsal interosseous m. and anastomosis with the terminal end of deep plantar arch

  • 2. 1st Dorsal Metatarsal a

    • runs along dorsal surface of 1st dorsal interossious m. →

      • dorsal digital a. (supplies medial and lateral sides of 1st digit and medial side of 2nd digit)