External anatomical structures of sparrowhawk (Accipiter nisus) encephalon

Abstract

The aim of this study was to determine the external anatomical structures of encephalon in the sparrowhawk. For this purpose, four brains of sparrowhawk were assessed for morphometric measurements and external structures. The average weight of the sparrowhawk brain was approximately 3±0,2 g., while the mean length, width and dorsoventral thickness of sparrowhawk brain were measured 24±2 mm, 19±2 mm and 4±1 mm respectively. Dorsal appearance of the sparrowhawk encephalon showed two cerebral hemispheres, cerebellum, lobus opticus, flocculus and cranial part of medulla spinalis. In lateral aspect of encephalon, pars frontalis cerebri, pars parietalis cerebri, and pars occipitalis cerebri were observed on lateral surface of the hemispherium cerebri from rostral to caudal. The well developed lobus opticus bulged laterally. In ventral view, two small and underdeveloped bulbi olfactorii projected from the rostral pole of the each hemispheres. There was no olfactory tract behind the bulbus olfactorius. Area behind the chiasma opticum constituted the brainstem structures. The midbrain, pons, medulla oblongata and medulla spinalis situated from cranial to caudal respectively in the brainstem. But, there was no distinct borders between the midbrain, pons and medulla oblongata.