The blood supply of the spinal cord
The arrangement of blood vessels supplying the spinal cord and the nerves arising from it may be summarised as intrinsic and extrinsic. The intrinsic blood supply delivers oxygen only to the spinal cord and the portion of the spinal nerves nearest to it.
Two intrinsic blood vessels run longtitudinally along the dorsal aspect of the cord (posterior spinal arteries) and another anterior longtitudinally down the front of the cord (the anterior spinal artery). These vessels themselves are fed by elements of the extrinsic system via a radiculopial branch which reaches the surface of the cord and irrigates the posterior spinal arteries. A radiculomedullary irrigates the anterior longtiudinal arterial access. Branches from the posterior spinal arteries encircle the cord as Vasa Coronae penetrating the superficial part of the white matter. sulco-commisural branches from the anterior spinal artery penetrate into the centre of the cord and radiate from the centre to supply the remainder of the cord.
The extrinsic blood supply irrigates the lining of the spinal cord the intrinsic system as well as bony elements of the spine. Because the body develops from a series of similar functional subunits like building blocks (known as metameres) each "segment" of the body bbegins with its own blood vessels a pattern that is intially repeated identically at each level but as development progresses some vessels regress or fuse with neighbours. Some persist predictably providing bblood supply to the intrinsic system over multiple segments and are known as metameric arteries. The best known of these is the artery of Adamkiewicz or arteria radicularis magna. In most people it arises on the left side in the mid-thoracic region. Persisting metameric arteries may also supply the cervical (artery of the cervical expansion) or lumbar areas.
Blood form the cord collects via two systems of veins, one ventral the other dorsally situated. They communicate by veins that traverse the cord.
Abnormal arteriovenous shunts affecting the spinal cord may be classified as follows:
- Type 1 Spinal Dural Arteriovenous Fistula
Acquired malformation of the extrinsic blood supply
- Type 2 Spinal Arteriovenous Malformations
analgous lesions to brain AVM developing from the intrinsic blood supply extrinsic blood supply
- Type 3 Metameric Arteriovenous Malformaitons
Very rare ongenital arteriovenous shunts formed from both the intrinsic and extrinsic systems. Multiple tissues may be involved and assosciated with other genetic conditions (see also: Parkes-Weber Syndrome, Spinal Arteriovenous Metameric Syndrome-SAMS, CLOVES syndrome)
- Type 4 Perimedullary Fistula
Acquired malformation of the intrinsic blood supply usually fromed from the anterior spinal arterial axis
Cavernomas also develop within the spinal cord although there is no abnormal shunting of blood from arteries to veins in that case and cavernomas cannot bbe deomstrated on an angioram although they are readily identified on MR imaging. The menu on the right of this page provides access to more information about the commonest spinal vascular malformations.