Review of the surface architecture of the equine neopallium: Principle elements of a cartographic pattern of sulci revisited and further elaborated

Abstract

The surface architecture of the equine telencephalon is far more complex and complicated than, for example, that of the carnivore's brain, and basic organization patterns are more difficult to recognize. This is due to species differences, to interindividual variations and even to asymmetries between right and left hemispheres. Moreover, a very heterogeneous anatomical terminology, especially in the pioneering older literature, does not allow easy access to a unanimous topographical orientation. This review article presents the key features of this heterogeneity and its anatomical and terminological backgrounds, focusing on the cerebral sulci. The abundant, often divergent data from the reviewed literature are displayed by means of graphical illustrations highlighting the key issues and comparing them with the terminology of the present Nomina Anatomica Veterinaria. These illustrations are supposed to convey the relevant conformities and discrepancies regarding locations, courses and names of cerebral sulci in an easier and more effective manner than written texts could possibly do with such a complex and heterogeneous matter. The data from the selected literature are supplemented by and discussed together with photographs and drawings of brains from our own collection. This combination of a classic review article and own findings is supposed to confirm, to further elaborate and to evaluate the key sulci serving as landmarks for an orientation on the equine neopallium. These are, laterally, the Sulcus suprasylvius, coronalis and praesylvius; dorsally, the Sulcus marginalis; and medially, the Sulcus genualis, cinguli and splenialis. Special attention is also given to the Fissura sylvia; a Fissura sylvia accessoria is proposed.

Equine Stereotaxtic Population Average Brain Atlas With Neuroanatomic Correlation

“…The manually segmented anatomic priors of the olfactory bulbs, rostral commissure, caudate nuclei, globus pallidus, thalamus, hypothalamus, optic chiasm, pineal gland, corpus callosum, fornix, hippocampi, amygdala, mesencephalon, pons, medulla oblongata and cerebellum are compared to corresponding transverse gross brain slices (Figure 5). The surface render of the brain atlas is compared to a gross brain specimen and corresponding sulci outlined according to the recent anatomic literature (Figure 6; Lang et al, 2018).…”

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

“…The distinct, appropriately narrow allocation and designation of sites on the neopallium was challenged by the complex gyration pattern, which is known to be extremely heterogenous in the equine brain [9,23,24]. The subdivision of the Facies convexa into 15 Sectors, in accordance with the recently introduced cartographic mapping system [5,13], was the key element for the objective and reproducible orientation on the neopallium.…”

“…The morphometric procedure applied here highlighted the topography of the equine brain in situ because, for the first time, extracranial landmarks were topographically linked to selected cerebral surface structures in horses (extra-intra calculations/measurements). The immanent biological variability of both, skull and neopallium [24], commonly influences the results of any morphometric procedure. To exclude growth-related differences, only adult horses (>5 years) were used in this study, bearing in mind that age-related differences in equine skulls have not been detected in horses older than five years [7].…”

“…The equine telencephalon recently attracted major scientific attention in veterinary medicine [16,24,34]; however, stereotactic maneuvers were performed in dogs [30], but not in horses (Equus caballus). Accordingly, our morphometric study was designed to elucidate the topographical relations between extracranial landmarks and intracranial sites on the neopallium.…”

“…Kramer et al used extracranial landmarks for a surgical approach to the brain [20]; Wijnberg, van der Ree, and van Someren used extracranial landmarks for the placement of electrodes for electroencephalography [35], but a comprehensive cartographic guideline is still not available. This may, in part, be due to the lack of a uniform reference system for the horse's head, and in particularto the very complex and heterogenous surface architecture of the equine neopallium [4,9,24]. The recently elaborated cartographic pattern subdividing the surface of the equine neopallium [5,13] was applied in this study as a promising tool to combine both, landmarks on the head and distinct sites on the brain's surface, for a comprehensive description of the topographical extra-intra relations.…”