182 The Elastic Tissue of the Human Larynx 



from the anterior extremities of the nodules described by Mayer. Inter- 

 spersed throughout this fibrous tissue are some cartilage cells and fine 

 elastic fibrils, which are verticalh' directed. (See Fig. 8.) 



Friedrich states that the perichondrium passes between the hyaline 

 substance of the thyroid cartilage and the median process described by 

 Gerhardt, and that it forms a distinct line of separation between the two. 

 He concludes, therefore, that there is no gradual transition from a hya- 

 line to an elastic cartilage, as is the case in the arytenoid cartilage, and 

 that Gerhardt is not justified in speaking of the process described by 

 him, as the processus A-ocalis of the thyroid cartilage. Friedrich found 

 no cartilage cells in the nodules occupying the anterior extremities of 

 the ligamenta vocalia. 



Katz(in stein," while agreeing with Friedrich in many points, takes 

 issue with him concerning the anatomical significance of the median 

 process. He states that the perichondrium is reflected upon the sides 

 cf the process, and that it does not form a line of separation between the 

 fibrous median process and the hyaline substance of the thyroid cartilage. 

 In establishing the perichondrial relation, he makes use of the law first 

 suggested by Eawitz, that the perichondrium exerts a directive influence 

 upon the orientation of cartilage cells. Upon the external surface of the 

 thyroid cartilage the cells are arranged parallel to the fibers of the peri- 

 chondrium. In the center of the cartilage they lie at right angles to its 

 long axis; upon the inner surface of the cartilage the cells are arranged 

 parallel to the fibers of the perichondrium, until the median process is 

 reached, where they are gathered into irregular clusters and some of the 

 cartilage cells are displaced posteriorly. Katzenstein agrees with Ger- 

 hardt regarding the anatomical significance of this process, and considers 

 it as quite comparable to the processus vocalis of the arytenoid cartilage. 

 Like Eeinke, in his work upon the ligamentum vocale, Katzenstein has 

 shown that the fibers are arranged in definite tension planes. 



In some of the lower animals, white rat, cat, etc., Katzenstein has de- 

 scribed between the laminae of the thyroid cartilage a wedge-shaped 

 cartilage, which is covered by elastic fibers anteriorl}-, and receives poster- 

 iorly the attachment of the anterior extremities of the ligamenta vocalia. 

 According to him, this wedge-shaped cartilage is the homologue of the 

 median process described by Gerhardt. 



While Katzenstein has accurately described the histological findings, 

 he has misinterpreted their anatomical significance. If the develop- 

 mental history of the thyroid cartilage be reviewed, some facts will be 



^•Katzenstein: Arch. f. Laryngol. u. Rhinol. Bd. xiii, pp. 336-337. 



