330 



ELEMENTARY PHYSIOLOGY 



LESS. 



middle line. They thus leave, in the middle line, a chink 

 or slit, running fx'om the front to the back, called the 

 glottis. The two edges of this slit are not round and 

 flabby, but sharp and, so to speak, clean cut ; they are 

 also strengthened by a quantity of elastic tissue, the fibres 

 of which are disposed length- 

 ways in them. These sharp 

 free edges of the glottis are the 

 so-called vocal cords, or vocal 

 ligaments. 



The thyroid cartilage (Fig. 

 103, Th) is a broad plate of 

 gristle bent upon itself into a V 

 shape, and so disposed that the 

 point of the V is turned forwards, 

 and constitutes what is com- 

 monly called "Adam's apple.' 

 Above, the thyroid cartilage is 

 attached by ligament and mem- 

 brane to the hyoid bone (Fig. 

 103, Hy). Below and behind, 

 its broad sides are produced 

 into little elongations or horns, 

 which are articulated by liga- 

 ments with the outside of a 

 great ring of cartilage, the 

 cricoid (Fig. 103, Cr), which 

 forms, as it were, the top of the 

 windpipe. 



The cricoid ring is much 

 higher behind than in front, and 

 a gap, filled up by membrane only, is left between its 

 upper edge and the lower edge of the front part of the 

 thyroid, when the latter is horizontal. Consequently, the 

 thyroid cartilage, turning upon the articulations of its 

 horns with the hinder part of the cricoid, as upon hinges, 

 can be moved up and down through the space occupied by 



Fio. 103. 



Diagram of the larynx, the 

 thyroid cartilag-e (Th) being- 

 supposed to be transparent, 

 and allowing the right ary- 

 tenoid cartilage (Ar), vocal 

 cords (V), and thyro-aryte- 

 noid muscle ( Th A ), the upper 

 part of the cricoid cartilage 

 (Cr), and the attachment of 

 the epiglottis (Kp) to be seen. 

 C.th, the right crico thyroid 

 muscle ; Tr, the trachea ; 

 Hy, the hyoid bone. 



