Anatomy of Spinal Cord Blood Supply in the Pig

Background In a species as popular in research as the pig, little information is available concerning the blood supply and vascular anatomy of the spinal cord and comparability to humans. Methods To visualize vessels contributing to the blood supply of the spinal cord, x-ray digital subtraction angiography and vascular casting by injection of a polymerizing solution of methylmethacrylate were used. Results The pig has larger internal thoracic arteries and subscapular arteries than the human, providing extensive collateral flow to the lower body, which offers blood supply to the spinal cord through the collaterals. The pig has a fine-caliber vessel plexus providing blood to the neck area, from which flow will reach both the spinal cord and the base of the brain. The segmental thoracic and lumbar arteries are relatively small in pigs, and they almost all originate as a single branch from the aorta and divide after 3 to 4 mm. The segmental vessels show a clear diminution after 2 to 3 cm at the level of the vertebral bodies. Pigs show major differences in the anatomy of the aortic bifurcation compared with humans. The median sacral artery in pigs is a large-caliber vessel, of a size almost comparable to the common iliac artery, with an isolated single dorsal branch leading to the spinal cord. Conclusions Documenting the anatomic differences in spinal cord blood supply between pigs and humans will aid in the planning of future experimental studies and in determining the clinical relevance of such studies.