Abstract
The right pulmonary artery runs obliquely across the ventral side of the tracheal bifurcation and across the ventral side of the right cranial lobe bronchiole, then runs across the dorsal side of the right middle lobe bronchiole. Thereafter, it runs between the dorsal and lateral bronchiole systems along the dorso-lateral side of the right bronchus and gradually comes to run along the dorsal side of the right bronchus. During its course, it gives off the arterial branch, running mainly along the lateral or dorsal side of the bronchiole. The left pulmonary artery also runs the same course as in the right lung, and similarly gives off the arterial branch. The pulmonary veins run mainly the ventral or medial side of the bronchiole and between the bronchioles. The right cranial and middle lobe veins form a short common trunk before entering the left atrium. The right accessory lobe vein enters the left atrium, directly. The left cranial lobe vein and one of the left middle lobe veins form a short common trunk before entering the left atrium. The remaining left middle lobe veins enter the left atrium independently. The pulmonary veins in the right and left caudal lobes form the right and left caudal lobe pulmonary venous trunk, respectively. They form a short common trunks before entering the left atrium.
