Sistematização, distribuição e território da artéria cerebral média e cerebroetmoidal na superfície do encéfalo em peru (Meleagris gallopavo)

Abstract

Background: The cerebral arteries constitute the main blood transportation via to the brain and play a fundamental role in the maintenance of normal cerebral activities. There are a few studies about the encephalic irrigation in the wild and exotic species. This study aims to describe and systematize the middle cerebral artery and cerebroethmoidal artery of Meleagris gallopavo, to determine a standard model and territorial area of irrigation, and the main variations in this species. Materials, Methods & Results: For this research, 30 brain with the cervical spinal cord segment of 10 male and 20 female young and adult turkeys (Meleagris gallopavo) were used. Discarded animals were provided from Doux Frangosul breeding center, located in Caxias do Sul city, State of Rio Grande do Sul, Brazil, 2006. Animals were euthanized with T 61, with an intravenous injection. After the removal of the skin, the sternum was removed, the common carotid arteries were cannulated through the brachycephalic trunks. The arterial system of the 30 animals were rinsed with saline solution with heparin and fi lled with latex colored in red. Animals remained immersed for one hour in running water, and next, the neck was sectioned. Next, a bone window was opened in the skullcap. Pieces were fi xed in 20% formaldehyde for seven days, and after this period, the brain was removed from the cranial vault, the dura-mater was removed and the arteries dissected for observation. Schematic drawings from all brains, the middle cerebral artery and cerebroethmoidal artery were prepared. Statistical analysis of the results was performed using percentage values. Nomina Anatomica Avium [2] was used for the designation of studied vessels. The territory of the middle cerebral artery comprehended the entire base extension of the cerebral hemisphere, except for a most medial and caudal triangular area, which was vascularized by the rostral cerebral artery. At the convex surface of the cerebral hemisphere, its territory reached the telencephalic vallecula. Its rostral hemispheric branches vascularized the frontal pole of the cerebral hemisphere and olfactory bulb, and also the rostral third of the sagittal eminence. The territory of the cerebroethmoidal artery and its ramifi cations vascularized a small triangular area at the base of the cerebral hemisphere between the middle cerebral artery and the optic chiasm, however its main vascular function in birds is to irrigate the entire nasal cavity. Discussion: The middle cerebral artery was projected in arch rostrolateromedialwards through the ventral surface of the cerebral hemisphere and gave off several perforating branches, which penetrated in the striated complex of the birds. It gave off ventral hemispheric branches, which were projected medialwards at the base of the cerebral hemisphere and disputed with the rostral cerebral artery for the vascularization of this area, and a sequence of lateral hemispheric branches, which ascended to the cerebral hemisphere, at the convex surface, at the level of the telencephalic vallecula and the terminal branch was the rostral hemispheric branches, which curved towards the lateral side of the olfactory bulb, ascending to the convex surface, vascularizing the most rostral third of the sagittal eminence. The cerebroethmoidal artery is the natural continuation of the rostral branch of the cerebral carotid artery, from the origin of the middle cerebral artery. It gave off as collateral branches the rostral cerebral artery, a small vessel projected from the cerebroethmoidal artery and the ethmoidal artery, which was projected rostralwards towards the olfactory bulb, following the interhemispheric fi ssure, reaching the olfactory bulb and the nasal cavity, through the olfactory foramen.