Blood Supply Spine

Blood Supply Spine


62 segmental arteries as 31 paired structures branches

- aorta 

- subclavian

- vertebral 

- internal iliac arteries 


Cervical spine 

- vertebral artery  (77%)

- additional supply is from branches of the subclavian artery (thyrocervical and costocervical)


Cervicothoracic spine

- branch from ascending pharyngeal in 60%

- vertebral artery responsible for only 36% of supply


Thoracic and lumbar spine

- aorta gives segmental arteries

- divide into lateral and dorsal branches 


Sacral spine

- internal iliac gives rise to iliolumbar artery (5th lumbar segmental artery) and lateral sacral artery

- additional supply from middle sacral artery


Blood Supply of the Spinal Cord 


General Features

- cord dependant on all three longitudinal vessels

- metabolic demands of grey matter greater than that of white matter

- longitudinal arterial trunks larger in cervical and lumbar regions due to ganglionic enlargements


Anterior Spinal Artery / ASA

- formed by union of anterior spinal branches of vertebral arteries at foramen magnum

- runs in anterior median fissure from medulla oblongata to conus medullaris

- narrows and may become absent in thoracic cord

- variable segmental supply

- probably supplies entire cord except posterior columns


Posterior Spinal Artery / PSA

- smaller than anterior spinal artery

- bilateral

- aries from posterior inferior cerebellar arteries or vertebral arteries at foramen magnum

- usually double running in between and behind posterior rootlets of spinal nerve

- anastomoses with anterior spinal artery particularly at conus

- may be noncontiguous areas

- variable segmental supply but more numerous and smaller than ASA


Segmental Supply

- average of 8 ASA radicular arteries (range 2-17)

- average 12 paired PSA radicular arteries (range 6-25)

- T4-T8 is narrowest portion of longitudinal supply and usually is fed by a single radicular artery

- thoracolumbar cord supplied by one or more prominent arteries


Artery of Adamkiewicz  

- originates on left from T9-T11 in 80% of cases (range T7-L4)


Cord Distribution

- ASA and PSAs give off central end arteries and peripheral branches

- central branches penetrate the cord via sulci

- peripheral branches anastomose with small pial branches of segmental vessels

- supply the periphery of the cord and are responsible for sacral sparing in ASA lesions


Venous Drainage


External venous plexus

- anterior to vertebral bodies


Internal venous plexus

- in epidural space

- anterior median spinal veins drains anterior cord


Posterior spinal veins are double and receive small radial veins from the posterior columns

- subsequent drainage into anterior and posterior medullary veins

- unite to form a segmental vein which anastomoses with the external plexus

- ultimate drainage into vertebral, azygous and lumbar veins and IVC


Surgical Considerations


T4-T9 is the critical vascular zone in which interference with the circulation is most likely to result in paraplegia


Principles of anterior spinal surgery

- ligate segmental spinal arteries only as necessary to obtain exposure

- ligate segmental spinal arteries at aorta rather than cord

- ligate segmental arteries on one side only

- limit dissection in vertebral foramina to a single level to preserve  anastomoses