The bronchial tree and blood vessels of the cow (Holstein) lung.

In the lung of the cow (Holstein), the right and left bronchi have the dorsal, lateral, ventral and medial bronchiole systems, respectively. Furthermore, the right lung has a tracheal bronchiole (bronchus). From the standpoint of bronchial ramifications, a bilobed cranial lobe and the middle, caudal and accessory lobes can be discriminated in the right lung, whereas a bilobed middle lobe and a caudal lobe can be discriminated in the left lung. The left cranial lobe is lacking. The right pulmonary artery runs obliquely across the ventral side of the trachea caudally to the origin of the cranial lobe bronchiole. It then runs across the dorsal side of the right middle lobe bronchiole, and thereafter along the dorsolateral side of the right bronchus. During its course, it gives off arterial branches running mainly along the dorsal or lateral side of each bronchiole. The left pulmonary artery runs the same course as that in the right lung. The pulmonary veins run mainly along the ventral or medial side of the bronchiole.