Spinal Cord Vascular Anatomy

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

• Vertebral and Spinal 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 and posterior horns.

• Anastomoses between the anterior and posterior arteries -- inconsistent {not sufficient to provide adequate spinal cord blood circulation}

• Radicular arteries {intercostal and 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.

• 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 and 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 and 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 and 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)