Extracranial guiding structures for navigation to specific topographical sectors of the equine neopallium : an anatomical investigation performing three-dimensional distance measurements in adult warm-blooded horses

This basically anatomical study focuses on two items; firstly, the establishment of a system for the cartographic subdivision of the neopallium; secondly, the topographical correlation of extracranial landmarks and intracranial sites on the neopallium. The surface of the neopallium was subdivided into 15 Sectors with reference to a newly introduced pattern of Primary Sulci. The topographical link between extracranial landmarks and certain intracranial sites (i.e., neopallium Sectors) was elaborated by using a simple stereotactic device and a computer-assisted measurement device. Measurements were performed between points on the head´s outer surface and on the isolated brain. The introduction of an anatomical three-dimensional Coordinate System was an essential key issue for this investigation. This setting facilitated the measurements and calculations of the so-called Indirect Distances that were characterized by their alignment along the three orthogonal axes (x, y, z) of the anatomical Coordinate System. The inter-individual comparison (16 adult horses [Equus caballus]) of the Indirect Distances revealed that each Sector Center lay within a distinct morphometric Residence Area. The measured and calculated data also showed that each Sector Center could be assigned to its proper extracranial landmark that - in comparison with other landmarks - was best suited for the optimal allocation of the Sector Center Point.