Spinal Cord Vascular Anatomy

• Primary blood supply (75%): anterior spinal arteries, arising from the vertebral arteries

vertebral artery anterior spinal artery posterior inferior cerebellar artery (PICA) basilar artery anterior inferior cerebellar artery (AICA) pontine perforating branches posterior cerebellar artery (PCA)

image: William G. Staten, R.T. (R) (ARRT), copyright November 1996

• Posterior spinal artery (25%): provides blood supply to part of the posterior columns & posterior horns.
• Anastomoses between the anterior & posterior arteries -- inconsistent {not sufficient to provide adequate spinal cord blood circulation}
• Radicular arteries {intercostal & lumbar artery branches}, anastamose with the anteroposterior spinal artery system
  •  Typically 8 (range 4-10) radicular branches-- cervical, thoracic, lumbar
  • Largest reticular artery: arteria radicularis magna {artery of Adamkiewicz) lower thoracic/upper lumbar region}
    • If: Origination is suprarenal, lower thoracic/upper lumbar, then only significant reticular artery
    • If: origination is infrarenal, associated with lumbar segments 2-4: indicative of good segmental cord blood supply -- probably due to another major radicular thoracic vessel.

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Hepatic/Portal Circulation

• Liver: Blood Supply
  •  Hepatic artery
  •  Portal vein
• Blood flow characteristics 
  •  20% of cardiac output {100 ml/min/100 g tissue}
  •  Hepatic blood flow
    •  65%-80% -- portal venous flow
    •  Remainder: hepatic arterial system
  •  Superior mesenteric + splenic + renal veins Portal Vein 

Peripheral Venous Circulation

• Cerebral:
  •  Internal +External jugular veins   subclavian veins bilaterally
  •  External jugular vein (variable/tortuous) course
    • Associated with two valves
      • valve 1: subclavian vein entrance
      • valve 2: 4 cm superior to the clavicle
• Arms:
  •  basilic (medial)   +  cephalic veins brachial vein
  •  brachial vein axillary vein subclavian
  •  bilateral subclavian veins superior vena cava (SVC)
• Cardiac:
  •  Great & Middle cardiac veins  +  a posterior left ventricular vein drain into the coronary sinus
  •  Near the great cardiac vein orifice, oblique vein of Marshall (vein of the left atrium) enters the coronary sinus
  •  Thebesian veins drain into cardiac chambers
  •  Thebesian venous flow + bronchial + pleural venous flow account for the expected 1%-3% arteriovenous shunt
• Legs: superficial & deep veins
  •  Primary superficial veins --
    • Greater Saphenous vein (located overlying the medial malleolus): may be used in aortocoronary  bypass graft surgery
    • Lesser saphenous vein: calf
  •  Saphenous vein +femoral vein (thigh) pelvis as the iliac vein
  •  Right + left iliac veins inferior vena cava (IVC)
  •  Right, left, middle hepatic veins enter the IVC
• Bronchial:
  • Extrapulmonary components of the proximal tracheobronchial tree azygos & hemiazygos veins (right side of heart) {azygos vein drains also perispinal regions and esophagus}
  • Bronchial venous drainage from intrapulmonary veins pulmonary veins (left side of heart)

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