ABSTRACT
Mesoscopic study of the irrigation of the lumbosacral segment of the spinal cord and the roots of the cauda equina was carried out in corpses of 18 Brazilian newborns of either sex. Through the abdominal portion of the aorta nine newborns were injected with neoprene latex and the others were injected with a 5% solution of gelatin coloured with black Indian ink. The latter were cleared by the Spalteholz technique. Two types of arterial distribution were determined: (a) proximal and distal radicular arteries supplying the corresponding roots, which presented in their middle third an arterial low density, that is, hypo-irrigation; (b) segmental spinal arteries, varying in number, more frequent on the left side and having a larger caliber than that of the radicular arteries, accompanying the roots without providing collateral branches to the neural roots and anastomosed with the spinal arteries.