The blood supply of spinal cord is mainly dependent on three vessels. These are namely anterior median longitudinal arterial trunk and a pair of posterolateral trunks. These posterolateral trunks are situated near posterior nerve rootlets.
These longitudinal arterial trunks are largest in size in the cervical and lumbar regions because the demand for grey matter is much more than white matter.
The size is much smaller in thoracic regions because of the same reason.
Generally speaking the blood supply of the spinal cord in the thoracic area is poor as compared to the cervical and lumbar region. The blood supply of the spinal cord is poorest between levels T4 and T9.
However, these are not the sole vessels on which blood supply of the spinal cord is dependent. There are many other reinforcing vessels. A list of other vessels supplying the spinal cord is as follows.
Radicular Arteries of The Cord
Also called medullary feeder arteries, these reinforce the longitudinal arterial channels.
These vary from 2-17 on the anterior side and 6-25 on the posterior side.
The vertebral arteries supply 80% of feeder arteries in the neck. In thoracic and lumbar areas the aorta gives rise to these vessels. In the sacral area, iliolumbar arteries, fifth lumbar arteries, middle sacral arteries, and lateral sacral arteries are important sources.
Vertebtral and Posteroinferior Cerebellar Arteries
These form additional important source of blood supply in cervical region.
Segmental arteries are at every level of the spine and occur in pairs. These supply both spinal and extraspinal tissues.
They originate from vertebral arteries in the neck, aorta in thoracolumbar area and lateral sacral artery in the sacral region.
In few people ascending pharyngeal artery is an important source of segmental arteries.
The segmental arteries branch profusely at intervertebral foramen and a second anastomosis occurs within the spinal canal in extradural region.
This anastomosis forms a rich network of vessels and allows to ligate segmental arteries without affecting the circulation of the cord.
Artery of AdamKiewz
It is the largest feeder of lumbar part of the spinal cord. It is on the left side between T9-T11 vertebrae in almost 80% of the people.
Venous drainage of the spinal cord is not as clearly defined as arterial circulation and can be highly variable.
Generally speaking, there are two sets of vessels
- Veins of spinal cord
- Venous plexus of Batson
Veins of the spinal cord are small veins and form a small component of the venous system. they drain into Batson plexus.
Batson plexus is a large and complex venous channel communicating directly with inferior and superior venae cavae. It extends from base of the skull to coccyx. The Batson plexus has three components
- Extradural venous plexus
- Extravertebral venous plexus
- Veins to osseous structures of the spine
The longitudinal venous trunks are called anterior and posterior venous channels.
Clinical Significance of Blood Supply of Spinal Cord
The knowledge of arterial circulation is important during surgical procedures. As for as possible the blood supply to the cord should be preserved.
As venous system communicates directly with large vessels, this interconnection allows metastatic spread from pelvis to the vertebral column.