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VEINS

SYSTEMIC VENOUS SYSTEM (figures from Moore Anatomy)

• inferior vena cava (see Figure 2-82) <--
  • hepatic veins (see below)
  • renal veins (+ gonadal veins)
• superior vena cava (Figures 7-43) <-- brachiocephalic <--
  • subclavian
  • cephalic vein
    • external jugular
    • internal jugular
• upper limb (Figures 6-57, 6-15, 6-16)
  • superior vena cava <-- jugular vein <--
    • internal jugular
    • external jugular <--
      • axillary vein (travels in axillary sheath)
  • in the arm and cubital fossa:
    • two brachial veins accompany the brachial artery to join the axillary vein
    • cephalic vein is located in the superficial fascia along anterolateral surface of biceps; superiorly cephalic vein runs between deltoid and pectoralis major and through deltopectoral triangle, where it empties into axillary vein
    • basilic vein is located in superficial fascia and passes on medial side of inferior part of arm; this becomes the axillary vein in the axilla
    • median cubital vein
      • forms the communication between the basilic and cephalic veins in the cubital fossa, where it lies anterior to the bicipital aponeurosis
      • median cubital vein <--
        • perforating vein
        • median antebrachial vein
• lower limb (Figures 5-7, 5-8)
  • superficial veins:
    • great saphenous vein
      • passes over medial malleolus of tibia to eventually drain into the femoral vein
      • many large tributaries of this vein exist
    • small saphenous vein
      • passes over posterior malleolus to eventually drain into the popliteal vein (although sometimes it ends in the great saphenous vein)
    • there are communications between the great and small saphenous vein
  • deep veins: these just follow the arteries (I think, but am not sure)
• varicose veins
  • normally blood flows from the superficial veins into the deep veins; to prevent flow in the opposite direction, there are valves between the perforating (communicating) veins
  • if these valves become incompetent, contraction of the calf muscles which normally propels blood superiorly causes a reverse flow through the perforating veins (i.e. from deep to superficial veins)
  • as a result, the perforating and superficial veins become tortuous and dilated (varicose veins)

PORTAL VENOUS SYSTEM

• portal vein and portal-systemic anastomoses
  • see Figure 2-40
  • introduction:
    • portal vein collects blood from abdominal part of GI tract, gallbladder, pancreas, spleen and carries it to liver
    • there it branches eventually into sinusoids, and is mixed with hepatic artery blood
    • it drains out of liver collected by hepatic veins
    • hepatic veins drain into inferior vena cava
  • formation of portal vein:
    • formed posterior to neck of pancreas by union of:
      1. splenic vein <--
         1. splenic vein (spleen)
         2. inferior mesenteric vein (descending colon, stomach) <-- superior rectal vein
      2. superior mesenteric vein (ascending colon, small intestine)
  • portal venous system communicates with systemic venous system in several locations - see Figure 2-83
    1. oesophagus
    2. rectum and anus
    3. umbilicus
  • these systemic anastomoses are clinically important; when portal circulation is obstructed (e.g. owing to liver disease), blood from GI tract can still reach the right side of heart through the inferior vena cava via these collateral routes; this causes veins in the anastomotic areas to dilate and become varicose