234 NORMAL HISTOLOGY AND ORGANOGRAPHY. 



cous membrane is covered in the greater part of its 

 extent with stratified columnar ciliated epithelium. 

 The cilia are found higher up the front wall than on 

 each side, reaching in the former to the base of the 

 epiglottis and at the sides to a point just above the 

 false vocal cords. Above these points the epithelium 

 is stratified squamous, like that of the pharynx. 



Upon the true vo- 

 cal cords the epi- 

 thelium is also 

 stratified squa- 

 mous. Mucous 

 glands are found 

 everywhere in 

 this membrane 

 but are particu- 

 larly abundant 

 upon the epiglot- 

 tis. 



The membrana 

 propria, on which 

 the epithelial cells 

 rest, is not only 

 very vascular but 

 has a rich supply 

 of elastic fibers 



and other connective-tissue elements. It is this tis- 

 sue that becomes edematous and greatly swollen in 

 infections, such as diphtheria. This is nature's 

 method of eliminating the disease, with, however, the 

 accompanying danger of suffocation. 



The vocal cords are transverse elastic ligaments 



Fig. 180. Diagram to illustrate 

 thyro-arytenoid muscles; the figure repre- 

 sents a transverse section of the larynx 

 through the bases of the arytenoid carti- 

 lages: Ary, arytenoid cartilage; p.m, proc- 

 essus muscularis; p.v, processus vocalis; 

 Th, thyroid cartilage; c.v, vocal cords; Oe 

 is placed in the esophagus; m.thy.ar.i, in- 

 ternal thyro-arytenoid muscle; m.thy.ar.e, ex- 

 ternal thyro-arytenoid muscle; m.thy.ar.ep, 

 part of the thyro-ary-epiglottic muscle, cut 

 more or less transversely; m.ar.t, transverse 

 arytenoid muscle. (Redrawn from Foster.) 



