Anatomical observations on the course of the azygos vein (vena azygos major).

In man, the azygos vein is described as ascending on the right side of the vertebral column until it curves anteriorly over the right bronchus to end in the superior vena cava. However, it has been observed that frequently the azygos vein is found to run part of its course on the left side of the midline. No description of this course has been found in current anatomical textbooks or other literature dealing with the subject (Morison, 1879; Butler and Balankura, 1952; Dal Zotto and Borsetto, 1954; Borsetto, 1956; Abrams, 1957). Azygos veins running on the left side have been observed in association with various malformations of the venous system, particularly a persistent left superior vena cava (Howden, 1886; McCotter, 1916; Smith, 1916; Huffmire and Bower, 1919; Keyes and Keyes, 1925; Butler and Balankura, 1952; Nguyen-Huu, 1957; Vakaet, Poppelier, and Vermeire, 1958). The present work is a study of variations in the course of the azygos vein in relation to the midline; it is considered that it may be of assistance in the interpretation of radiographs of the azygos and other veins (Ottonello, 1931; Burke and Goldberg, 1949; Stauffer, LaBree, land Adams, 1951; Fischgold, Adam, Ecoiffier, and Piequet, 1952; Fleischner and Udis, 1952; Ellis and Bruwer, 1954; Suisse and Aurig, 1954; Tori, 1954; Lucarelli, Carnevali, and Vincre, 1955; Shuford and Weens, 1958; Schwartz, Handel, and Candel, 1959) as well as in the surgery of the region.