blood supply to spine

Arterial

Segmental vessels

Origin

Cervical

· C1 to C7

· segmental vessels arise from vertebral arteries

· enter O-C1 to C6-7 foramina

· C8

· deep cervical artery

· is branch of costocervical trunk from 2nd part of subclavian artery

· enters C7-8 foramen

Thoracic

· T1 and T2

· from superior intercostal artery

· is branch of costocervical trunk from 2nd part of subclavian artery

· divides into 2 branches

· enter T1-2 and T2-3 foramina

· T3 to T11

· intercostal arteries arising from thoracic aorta

· enter T3-4 to T11-2 foramina

· T12

· subcostal artery from thoracic aorta

· enters T12-L1 foramen

Lumbar

· L1 to L4

· segmental vessels arise from posterolateral aorta

· enter L1-2 to L4-5 foramina

· L5

· iliolumbar artery

· arises from internal iliac artery

· enters L5-S1 foramina

Sacral

· S1 to S5

· segmental vessels from lateral sacral arteries

· arise from internal iliac artery

Vessels

Vertebral

· ascending and descending branches

· form network on front and sides of body

· penetrate vertebra

Extraspinal

· anterior and posterior branches

· given off just proximal to foramen

· supply

· paravertebral muscles

· facet joint and posterior lamina

Spinal

· given off just proximal to foramen

· enters foramen

· divides into

1. radicular branches

· supply dorsal and ventral nerve roots

· usually do not reach spinal cord

2. anterior and posterior branches

· form anastamotic mesh on surface of spinal canal

spinal cord

Three vessels

· cord dependent on 3 longitudinal vessels

· each extends from medulla oblongata to conus medullaris

Anterior median longitudinal trunk

· is anterior spinal artery

· formed by union of 2 branches of vertebral artery

· runs in anterior median fissure

· gives central (sulcal) branches

· supplies anterior 2/3 of cord

Pair of posterolateral longitudinal trunks

· are posterior spinal arteries

· derived from vertebral artery or posterior inferior cerebellar artery

· run anterior and posterior to posterior rootlets

· supply posterolateral 1/3 of cord

Medullary feeders

· arise from segmental arteries

· reinforce longitudinal trunks

· present where need for blood supply greatest

· cervical and lumbar limb expansions

· average of 8 anterior and 12 posterior feeders

· particularly large feeder

· usually enters on left at T9 to T11

· called artery of Adamkiewicz or arteria radicularis anterior magna

· supply of cord least rich from T4 to T9

· critical vascular zone

Venous

· all valveless vessels

drainage

Vertebral column

· majority of blood drains posteriorly into basivertebral veins

· emerge from foramina in posterior surfaces of vertebral bodies

· some blood drains anteriorly

· into anterior external plexus

Spinal cord

· drains into venous plexus in pia mater

· this drains into internal venous plexus

Plexuses

Internal venous plexus

· lie within vertebral column

· two groups

Anterior plexus

· lie on posterior surfaces of vertebral bodies

· receive basivertebral veins

Posterior plexus

· lie on anterior surface of posterior elements

External venous plexus

· lie outside vertebral column

· two groups

Anterior plexus

· in front of vertebral bodies

· receives some blood from vertebral bodies

Posterior plexus

· behind posterior elements

segmental veins

· external and internal venous plexuses drain into intervertebral veins

· these drain into segmental veins

· segmental veins correspond to segmental arteries