A systematic study of the brain base arteries inbroad-snouted caiman (Caiman latirostris)

ABSTRACT

The objective of this study was to describe and systematize the encephalic arterial vascularization of this reptile,by providing a standard irrigation model with its major variations. Thirty broad-snouted caiman heads andtwo whole specimens were used. The arterial system was filled with red-colored latex. Only a single source ofblood supply was observed in caimans and it originated from the left aortic arch. This vessel is called the azygoscarotid artery. At the caudal base of the skull, ventral to the first cervical vertebrae, it divided into two internalcarotid arteries. The internal carotid arteries divided into a rostral branch and a short caudal branch at thehypophysis level, which continued naturally as the caudal cerebral artery. The short caudal branch gave off itsmedium-caliber portion which, gave off the mesencephalic and the ventral rostral cerebellar arteries. Then thiscaudal branch anastomosed with its contralateral counterpart, forming the basilar artery. This artery followedthe ventral median fissure of the medulla oblongata, giving off the ventral caudal cerebellar and dorsal spinalarteries, and abandoning the cranial cavity through the foramen magnum as the ventral spinal artery. Therostral branch gave off the middle cerebral, rostral cerebral and rostral communicating arteries. The middlecerebral artery arose from a network originated from one to five collateral branches of the rostral branch of theinternal carotid artery. It was observed that the cerebral arterial circle was rostrally and caudally closed and,therefore, the cerebral blood supply was exclusively made by the carotid system.