CHAPTER V. 



DISSECTION OF THE LARYNX. 



The larynx is a short tube forming the upper part of the windpipe. 

 It is, however, not merely a part of the respiratory apparatus, but is 

 also the organ of voice. It possesses a framework of cartilages, which 

 are movably articulated together, and connected by ligaments or 

 membranes. These cartilages are moved by muscles, some of which 

 pass between the different cartilages and constitute an intrinsic group, 

 while others pass between the cartilages and extraneous parts, and con- 

 stitute an extrinsic group. 



Directions. — Provided the dissection has to be canied out on one 

 larynx, the study of the muscles must precede that of the cartilages. 

 When another larynx can be procured, it is more advantageous to 

 reverse this order, removing the muscles from the first larynx in order to 

 study the cartilages and their mode of union, and then using the other 

 for the examination of the muscles and remaining structures. 



Even when the first method has to be followed, it is advisable, before 

 proceeding to dissect the muscles, to read the description of the cartilages, 

 which is therefore here put first. 



CARTILAGES OF THE LARYNX. 



These are five in number, viz., the cricoid, thyroid, and epiglottis, which 

 are single ; and the pair of arytenoid cartilages. In man there are two 

 additional pairs — two cornicula laryngis and two cuneiform cartilages. 

 In the horse the first of these are amalgamated- with the tips of the 

 arytenoids, while the cuneiform cartilages are small, shot-like bodies 

 included in the aryteno-epiglottic fold of mucous membrane. 



In the natural position of the animal at rest, the long axis of the 

 larynx is oblique upwards and forwards. For convenience of description, 

 however, we may assume it to be vertically plated, as indeed it is when 

 the head and neck are extended (elevated) to the fullest' degree. In this 

 position the cartilages are related to one another as follows : — The cricoid 

 is the lowest, aM is connected to the first ring of the trafchea. The thyroid 

 is placed above this, and bounds the tube of the larynx in front and at the 

 sides. The arytenoids surmount the cricoid behind, and the epiglottis 

 is superposed to the thyroid in front of the upper aperture of the tube. 



