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 

 constitute an extrinsic group. 



Directions. — Provided the dissection has to be carried 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 descrip- 

 tion, however, we may assume it to be vertically placed, 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, and is connected to the first 

 ring of the trachea. 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. 



