Morphologic study of the adult trachea at the 7th and 12th ring. A study on specimens from 205 autopsies

During 205 autopsies in Finland, the seventh and twelfth tracheal ring were collected and their cross-sectional shapes and measurements were recorded. Six already known cross-sectional shapes were found, appearing with frequencies which differ from previous studies. New finding: the shape of the seventh ring was different from that of the twelfth in 46% of the male and in 60% of the female cases.