350 



PULMONARY MUCOUS TISSUE. 



point of attachment for the vocal cord, and occupies the an- 

 terior three-fifths. 



Fig. 87. External posterior surface of the 

 crieoid and arytenoid cartilages.* 



Fig. 88. Anterior surface of the 

 cricoids and the arytenoids.f 



If the anterior angle of the arytenoid cartilage be turned 

 outwards, the glottis will be dilated, and take the shape of a 

 lozenge or rhomb (Fig. 89). This effect is produced by the 

 contraction of the posterior crico-arytenoid muscle, which is 

 inserted in the external angle of the arytenoid cartilage, and 

 produces a rocking of the thyroid upon the crieoid cartilage 

 (mouvement de sonnette). 



If the anterior angle of the arytenoid cartilage be turned 

 inwards, the anterior portion of the glottis takes the form of a 

 slit, which is widened posteriorly into a small inter-arytenoid 

 triangular aperture (Fig. 90). 



Finally, this latter opening may be itself reduced to a slit 

 by a second movement which brings the two arytenoids close 

 together (Fig. 91). The first action is produced by the 

 lateral crico-arytenoid muscle, which causes the arytenoid 

 cartilage to swing in a contrary direction to that of the 



* , Crieoid cartilage. 5, Its median projection, c, Articulating thyroid 

 surface, rf, Lower edge, c, Upper edge. J, Posterior surface of the arytenoid 

 cartilages, i, Articulating arytenoid surface of the crycoid cartilage, m, Mus- 

 cular process (external angle of the base of the arytenoid). t?, Vocal process, 

 contracted (anterior angle of the base of the arytenoid). r, Small cornua. 

 (L. Mandl.) 



t Crieoid cartilage, inner surface. 6, Section of the surface of the annular 

 portion after removal. (/, Lower edge, e, Upper edge of the crieoid. m, Mus- 

 cular process (external angle), v, Vocal process (anterior angle), r, Small 

 cornua. i, />, /, /, , Protuberances and depressions of the antero-external surface 

 of the arytenoid, which serve aa points of insertion, being muscular in the case 

 of the most external fibres of the thyro-arytenoid, and ligameutous in that of 

 the upper \ ical cords. (L. Mandl.) 



