AUTHOR'S ABSTRACT OF T H I S PAPER ISSUED B Y THE BIBLIOQRAPHIC SERVICE, AUGUST 7

AN UNUSUAL RIGHT LUNG MATTHEW MARSHALL

Anatomical Laboratories, The School of Medicine, University of Pittsburgh

In the course of the regular dissechion an unusual right lung was found recently.

1. A rudimentary middle lobe so hidden in the interlobular fissure as to make the lung appear two-lobed from a simple surface inspection, and

2. An unusual distribution of the second lateral broncfius. The inferior interlobular fissure did not reach the diaphrag-

matic surface, but turned around the ventral margin on to the mediastinal surface and thence dorsalward and slightly upward to the hilus. The superior interlobular fissure separating the middle and superior lobes was not evident from the mediastinal surface; that is, there was no evidence of a middle lobe from surface inspection of the mediastinal surface of the lung. On widely divaricating the inferior interlobular fissure, the middle lobe could be seen near the mediastinal surface, lying in a position ventral to a frontal plane passing through the hilus. It was shaped as a biconvex disc about 1 cm. thick, elongated in a dorsoventral direction, with its medial edge very close to and parallel with the mediastinal surfade of the lung, and its lateral edge roughly parallel to the medial edge and about 4 em. from the mediastinal surface of the lung. The dorsoventral length was about 5 cm. It was attached dorso- medially to the hilus, the remainder being covered by pleura except the ventral extremity, which was fused with the superior lobe. Thus it was ihcompletely separated from the upper lobe by the superior interlobular fissure.

The relations of the structures at the hilus were those of a normal right lung. When traced deeply into the lung substance .the relations of the eparterial bronchus and vessels of the superior

In brief, its interesting features were:

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102 MATTHEW MARSHALL

lobe were found to be normal. The second lateral bronchus, the normal bronchial supply of the middle lobe, w&s observed, how- ever, to send a large branch to the upper lobe, taking a path through the fusion between the middle and superior lobes, while it supplied only a small branch to the middle lobe. The main-stem branches proceeded into the inferior lobe in the usual manner’.

The tendency of the middle lobe to fuse with the superior lobe is well known. The diversion of the distribution of the larger part of the second lateral bronchus to the upper lobe in this case seems to suggest there is some parallelism between the extent of fusion of these two lobes and the distribution of the second lateral bronchus to the superior lobe.

This lung merits recording since: 1) it shows an extreme variation in the relations of the interlobular fissures of the right lung, and, 2) it presents a well-marked case in which an upper lobe of the right lung receives the major part of the bronchial distribution of the second IateraI bronchus, and the middle lobe receives the minor part.