Abstract
In the bronchus tree of human being, a small branch of bronchus can be recognizied under Bronchus media. This small bronchus is named as Br. cardiacus or Br. basalis medialis in the International Terminology of Anatomy. It is, however, not lobulating indepenently in human being. While, the same in mammalian animals is evidently lobulating and is named as Lobus infracardiacus or Lobus intermedius. Stated in the following are the findings of the study of the comparative anatomy of Br. infracardiacus contained in the Lobus infracardiacus on a number of mammalian animals.
1. Insectiva, Rodentia, Carnivora, Artiodactyla and Cercopithecus of Primates have an independent Lobus infracardiacus containing Br. cardiacus, while in the human being, Br. cardiacus is embedded in the Lobus inferior of the right lung.
2. Br. cardiacus of the human being starts from the trunk of Br. inferior with an angle of approximately 90°inwardly against Br. media, so that, it corresponds to a parabronchus. In other animals too, as it develops from the inside with an angle of 60-95°, it is a parabronchus.
3. The position of the artery which accompanies Br. infracardiacus is different in each animals, and this difference influences on the locality of the formation of Lobus cardiacus.
4. Br. cardiacus of the human being resembles to other of other mammalian animals but differs on the point that it does not lobulate. This probably is due to the narrowing of the mediastinal cavity caused cy the standing up of the human being and then it caused the embeding of Br. cardicaus in the Lobus inferior of the right lung.
