190 The Elastic Tissue of the Human Larynx 



parallel to the fibers of the ligament, and to the mucous folds found at 

 this level. The elastic fibers enter the bases of the latter, but do not pass 

 vertically into them. An exception to the latter statement is found upon 

 the medial surface of the vocal process of the arytenoid cartilage, where 

 the fibers of the subepithelial layer pass vertically or obliquely into the 

 base of a small mucous fold. This change in direction of the elastic 

 fibers corresponds approximately to the level at which the linea arcuata 

 inferior of Eeinke ^^ crosses the vocal process. This line limits the extent 

 of an oedema of the labium vocale posteriorly; the vertical arrangement 

 of the elastic fibers probably acts as a barrier at this point. This 

 arrangement may have some further functional import. In this region 

 the epithelium is subject to the greatest stress, owing to the frequent 

 and wide range of movement of the processus vocalis. The arrangement 

 of the elastic fibers here undoubtedly anchors more securely epithelium to 

 vocal process. Eeinke states that occasionally a similar relation between 

 epithelium and subepithelial elastic layer is found at the level of the 

 nodulus vocalis. I have not found this relation in my specimens. In the 

 subglottic region the subepithelial elastic fibers are separated from the 

 epithelium by a thin connective tissue layer. The elastic fibers are here 

 vertically directed. The same relation is found in the inter-arytenoid 

 space, and in the superior laryngeal zone. 



I am indebted to Mr. Leonard H. Wilder, artist to the laboratory, for 

 the accompanying drawings. 



ExPLAXATio:Nr OF Plates. 



PLATE I. 



Fig. 1. — Frontal section through the anterior part of the conus elasticus. 

 1. Thyroid cartilage. 2. Elastic fibers of the conns passing mediad on each 

 side to form the ligamentnm cricothyreoideum medium, which is pierced by 

 the crico-thyroid vessels. Most of the fibers pass cephalad and laterad from 

 the cricoid cartilage to attach to the thyroid cartilage. Some arise from a 

 raphe formed by the union of the horizontal fibers of the ligament. 3. Cri- 

 coid cartilage. 



Fig. 2. — Frontal section through larynx, just posterior to the anterior com- 

 missure. 1. Thyroid cartilage. 2. Cricoid cartilage. 3. Fibers of the conus 

 elasticus. 4. Nodulus vocalis, showing the convergence of the elastic fibers of 

 the ligamentum vocale upon its medial surface. 5. Musculus vocalis. 6. Ven- 

 triculus laryngis. 7. Ligamentum thyreo-epiglotticum. 8. Subepithelial elas- 

 tic layer separated from the elastic fibers of the conus by glands and colla- 

 genic tissue. 



Fig. 3. — Transverse section through the ligamentum cricothyreoideum 

 medium, showing its relation to the fibers of the conus and the subepithelial 

 elastic layer. 



"Reinke: Fortschritte der Medicin. 1895, p. 476. 



