The Vertebral Level of the Arytenoid Cartilages HAROLD J. KOPPEL,' GEORGE S. KENDRICK AND JAMES E. MORELAND Department of A n a t o m y , Baylor University College of Dentistry, Dallas, T e x a s ABSTRACT A group of 27 females and 24 males between the ages of eight years four months and 15 years seven months was examined to determine the vertebral level of their arytenoid cartilages. A n appraisal of their lateral cephalometric radiographs which included the cervical vertebra was made under rigid conditions. Each cervical vertebra was divided into three sections in order to relate its position more precisely to the cartilages. The age of each subject was recorded and then compared with the vertebral level of their arytenoid cartilages. General consistency seemed to prevail throughout the group at given sex and age levels. Visualization of the arytenoid cartilages was excellent. No evidence of mineralization in the laryngeal cartilages was noted in the age group studied. Although most of the current anatomy texts, such as Gray ('66), Cunningham ('64), Grant ('62), Lockhart, Hamilton and Fyfe ('59), describe the vertebral level of the cricoid cartilage, they fail to give the position of the arytenoid cartilages. It could be left to the assumption that location of the cricoid cartilages, which are described rather thoroughly, would suffice for the arytenoids, since they are contiguous. Therefore, due to descriptive inconsistencies of these cartilages with respect to their vertebral level as recorded in anatomy texts, the present study was undertaken. MATERIALS AND METHOD The lateral cephalometric radiographs on 51 subjects, 27 females and 24 males, between the ages of eight years four months and 15 years seven months were utilized. These radiographs were taken with the teeth in occlusion and according to the methods of Broadbent ('31), Hixon ('60), Knowles ('62) and Thurow ('51). Exposure and developing were kept constant to standardize the quality of the radiographs. All of the subjects were Caucasoid and without musculoskeletal or other determinable defects. There were no siblings, Negroid or Mongoloid individuals in the group. Accurate tracings were made of each subject by extending a line through the ANAT. REC., 160: 583-586. base of the arytenoid cartilage to one of the three parts of the corresponding vertebra (figs. 1, 2). Following the completion of these tracings, another person was selected to trace a sample group to see if there was a variation in the method. The tracings made by him were compared with the original group. There was such close similarity in the interpretation of the arytenoid-vertebra relation that the present study was completed. OBSERVATIONS The chief finding of this study on 27 females and 24 males revealed the vertebral level of the arytenoid cartilages to vary with age and sex (fig. 3 ) . However, 39 of the 51 subjects studied were seen to exhibit less than one vertebra difference in the vertebral level of their aryteniod cartilages. There was no constant descent with age (fig. 3 ) ; nor was it shown that the arytenoids are at a higher vertebral level in males than in females of the same age. DISCUSSION The inferior limit of the larynx and the beginning of the trachea and esophagus corresponds to the lower border of the cricoid cartilage. Luschka (1871), Rudinger (1873) and Braune (1875) illustrated this level at the lower border of the sixth cervical vertebra in the adult, with IThesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Dentistry, Baylor University College of Dentistry, 1967. 583 584 HAROLD J. KOPPEL, GEORGE S . KENDRICK AND JAMES E. MORELAND Fig. 1 A typical radiograph used in this study illustrating the arytenoid cartilages. Soft palate Spine of atlas Tongue Tip of epiglottis Body of hyoid bone Arytenoid eminence and lower thirds Fig. 2 A typical tracing of the arytenoid cartilages illustrating division of the cervical vertebra. 585 THE ARYTENOID CARTILAGES Males Females wfmn c4u -1 u C4M 2 -1 2 C4L sw> c 5 u I W c5w CSL t ,J'I 4' 1 C6U a I I I I I I I I 9 10 11 12 13 14 15 16 AGE I N YEARS Fig. 3 A graph illustrating the vertebral level of the arytenoid cartilages in male and female subjects. the head erect. Rudinger (1873) also noticed that the level was higher in infants. Symington (1881-1885) postulated that this downward displacement in adults is caused by the growth of the facial portion of the skull and not by the vertical growth of the larynx exceeding that of the vertebral column during growth from childhood to adulthood. He concluded that at puberty the larynx has achieved its adult position. Lisser ('11-'12), Testut ('14) and Rouvi2re ('24) also observed a gradual descent of the larynx with age but the latter included the observation that the laryngeal position was lower in males than in females of the same age. Negus ('49), disagreeing with Symington (1881-1851), postulated that laryngeal descent is due to an assumption of erect posture and recession of the jaws. He also observed that the larynx terminated opposite the middle of the sixth cervical vertebra in a seven month old fetus and in a newborn. Bench ('63) however, stated that the larynx terminates between the third and fourth cervical vertebra in the newborn. He also established a close relation of vertical growth of the face to growth of the neck in preschool and postpubertal groups, According to him a higher correlation exists in postpubertal ages. Thompson and Kendrick ('64) have shown the face to exhibit vertical growth in the third and fourth decades of life. While no mention of the larynx was made, changes in this area may also occur. That females usually reach puberty ahead of males is well documented. For this reason, one may assume the arytenoid cartilage of the female group to be inferior to the males of the equivalent age. This occurrence was not consistently recorded in the present study. CONCLUSIONS An attempt has been made to relate the arytenoid cartilages to the cervical vertebra while using the living subject. A review of literature has failed to present this relation. That the cricoarytenoid cartilage complex may continue to descend after puberty is suggested on the basis of the present study. While some variation exists, consistency was ever present in the arytenoid-vertebra relation when sex and age were considered. Hopefully, it will not be too long before more information is 586 HAROLD J. KOPPEL, GEORGE S . KENDRICK AND JAMES E. MORELAND presented on the relation of these anatomical structures. LITERATURE CITED Bench, R. W. 1963 Growth of the cerical vertebra as related to tongue, face, and denture behavior. Am. J. Orthodont., 48: 183-214. Braune, H. 1875 Topographisch-anatomischer atlas. Broadbent, €3. H. 1931 A new x-ray technique and its application to orthodontia. Angle Orthodont., 1: 45-66. Goss, C. M. 1966 Gray's anatomy. Lea and Febiger, Philadelphia. Grant, J. C. B. 1962 A n atlas of anatomy. 5th ed., The Williams and Wilkins Co., Baltimore. Hixon, E. H. 1960 Cephalometric and longitudinal research. Am. J. Orthodont., 46: 3642. Knowles, C. C. 1961 Cephalometric studies of the skull. Brit. J. Plast. Surg., 14: 315-324. Lisser, H. 1911-1912 Studies on the development of the human larynx. Am. J. Anat., 12: 27-66. Lockhart, D., J. Hamilton and T. Fyfe 1959 Anatomy of the human body. J. P. Lippincott Co., Philadelphia. Luschka, P. 1871 Der Kehlkopf des Menschen. Tiibingen. Negus, V. E. 1949 The comparative anatomy and physiology of the larynx. Grune and Stratton, Inc., New York. Romanes, J. 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