The arterial supply to the brain of the yak (Bos grunniens)

Fifteen head specimens of the yak were dissected to study the arterial supply to the brain. The supply comes from the internal carotid, maxillary, occipital and vertebral arteries. Except for the internal carotid artery, the branches of the above-mentioned arteries contributed in the formation of the rete mirable of which the vascular diameter was larger and the wall was thinner. The brain was mainly supplied by branches from the internal carotid and vertebral arteries in which the blood is oxygenated. These branches joined to form the circle of Willis (Circulus arterious cerebri) in the region of the pituitary gland. The arterial supply to the cerebrum was mainly provided by the middle and rostral cerebral arteries, which arose from the internal carotid. The basilar, cerebellar and caudal cerebral arteries came from the vertebral artery. However, the adult yaks do not have the rostral communicating artery. The outer diameter at the origin of the vessels ranged from 0.40 to 2.60 mm. The outer diameter of the left arterial vessel at its origin was larger than the same vessel of the right by about 0.20 mm in the all samples.