Arterial supply of the interpeduncular part of the human oculomotor nerve

The aim of this study was a detailed examination of the arterial vascularization of the interpeduncular cisternal part (ICP) of a proximal segment of the human oculomotor nerve (ON). The blood vessels of the ONs were carefully microdissected and studied in 30 brain hemispheres using 6.3× to 20× magnification of the stereoscopic microscope. The arteries were injected with the mixture of 10% India ink and gelatin. For better understanding, one brainstem specimen was prepared following a histological procedure, transversely serially cut into 5-μm thick slices, and stained with Luxol fast blue. Another injected midbrain specimen was cut in 1-mm-thick transverse sections, completely cleared with methylsalycilate, and analyzed under transmitted light. The common oculomotor arteries (COAs) and the small oculomotor branches, which participate in the vascularization of the dorsal and ventral surfaces of the ICPs of ONs, were analyzed and their diameters were measured. The dorsal COA was present in 83.33% of the ONs, one per nerve, with an average diameter of 213.57 μm. The ventral COAs were found in 76.67% of the ONs, one per nerve, with an average diameter of 137.64 μm. The mean diameter of the dorsal COAs was significantly higher than the mean diameter of the ventral COAs (<i>p</i> < 0.001). The oculomotor fine central vessels supplied the oculomotor root exit zone (OREZ) with the central type of myelin, and distally, fascicles of the rest of ICS with the peripheral type of myelin. The results describing the ON arteries may have diagnostic and microsurgical significance. The lack of detailed morphological analysis of the dorsal region related to the ventral arterial vessels of the ICP, along with measurements of the oculomotor arterial diameters, guided us to conduct this anatomical research to improve diagnostic procedures and the quality of microsurgical interventions in this region.