Linea splendens

Linea splendens is the term used to describe the thickening of the spinal epipial layer along the ventral surface of the spinal cord. It covers the entire length of the anterior median fissure.

Within the spinal cord, the pia mater can be divided into two layers. The inner layer called the intimal pia layer, is the actual pia mater and tightly surrounds the spinal parenchyma. The outer layer, is the spinal the epipial layer or intermediate meningeal layer. The latter becomes thickened anteriorly along the length of the anterior median fissure, consisting of dense collagenous tissue, forming a structure called the linea splendens.

The linea splendens covers the anterior spinal artery and vein that lie within the anterior median fissure. This means that the artery and vein are located in the sub-eippial space. However, due to the presence of numerous pores in the thickened epipial linea splendens, cerebrospinal fluid can circulate through these pores. As a result, the fluid can travel between the subarachnoid space and the sub-epipial space where the anterior spinal artery and vein are located. This functional arrangement is similar to the positioning of cerebral arteries and veins, which reside within the actual subarachnoid space in the brain.