Collateral branches of the aortic arch in the greater Rhea (Rhea americana americana Linnaeus, 1758)

The greater rhea (Rhea americana americana) is a bird of the Rheidae family, and is known as a ratite for being a flightless bird. This animal has great reproductive and productive potential, according to the products and by-products that it can provide such as meat, leather, feathers and fat which are very popular in the world market. Given its economic importance and lack of information in the literature on its morphology, especially in regard to its cardiovascular apparatus, this study aimed to describe the collateral arteries of the aortic arch, in order to establish the origin and distribution of arteries and thus contribute information to the biology of the species. The bodies of 20 young and adult rheas of both sexes which had died from natural causes and were being stored in a freezer at CEMAS / UFERSA were used. The study was approved by CEUA /UFERSA (Opinion No. 09/2015, process No. 23091.004968 / 2015-23). The animals were thawed and had the cannulated thoracic aorta artery and the vascular system perfused with Neoprene 450 latex colored with yellow pigment. Subsequently, the animals were fixed in 3.7% aqueous solution of formaldehyde, and after 72 hours dissections were carried out, images were obtained and schematic drawings were prepared. The right and left brachiocephalic trunks emerged from the aortic arch in 100% of the specimens from the right brachiocephalic trunk origined a common trunk the thyroid arteries, syringotracheal trunk, vertebral artery, superficial lateral cervical artery, basecervical artery, and ascending esophageal artery. The left brachiocephalic trunk collaterally stemmed in the left common carotid artery, which in turn led to the left internal carotid and a common trunk which stemmed the thyroid arteries, the syringotracheal trunk, vertebral artery, superficial lateral cervical artery, basecervical artery and descending esophageal artery. At the end of its trajectory, the right and left brachiocephalic trunks give rise to the right and left subclavian arteries, which in turn, stem the sternoclavicular, axillary, and intercostal arteries, pectoral trunk, cranial pectoral arteries, pectoral caudal artery and collateral branches of the pectoral trunk. Based on the results, it was concluded that the aortic arch in rheas issued right and left brachycephalic trunks.