Anatomy and Physiology of the Larynx, 77 



this angle is named the 'processus vocalis (Fig. 3, 3). The 

 posterior angle is thick and blunt, and, owing to its receiving 

 the insertion of the powerful and important dilator muscle 

 of the larynx, it is termed the processus muscularis (Figs. 

 1, i i; 2, g g ; 4f, f f). The apex of each arytasnoid carti- 

 lage, and which is bent backwards to form a lip, is actually 

 made up of a thin piece of elastic cartilage, named the 

 " cartilage of Santorini " {capitulum Santorini), and cor- 

 responds to the cornicula laryngis of man. The horse 

 has extremely rudimentary " cartilages of Wrisberg." 



The two cartilages meet in the middle line, where they 

 are united by a ligament, the transverse arytsenoid (liganien- 

 tuTii arytcenoideum transversmn) , and at their base they 

 are united to the cricoid cartilage by another ligament 

 {iiga.mentum crico-arytcenoideumi), which forms the cap- 

 sule of the joint existing between the cricoid and arytoenoid 

 cartilages. This joint allows of rather extensive movement ; 

 the two aryta^noids, when acted upon by their abductor 

 muscles, swinging outwards and upwards from the middle, 

 around a vertical axis, like a double door hinged in the 

 centre ; so that the vocal cord on each side, attached to the 

 lower angle of the arytienoid cartilage, is pulled in the same 

 direction, and the opening in the larynx between the car- 

 tilages and cords is thereby greatly increased. This move- 

 ment we shall have to refer to frequently. 



4. Epiglottis (Figs. l,d;2,e ef; 3, g ; 4, a).— This is a 

 very elastic piece, placed above the thyroid cartilage, in 

 shape like a sage leaf, and, except during the act of swallow- 

 ino\ it is curved forward towards the mouth. It circum- 

 scribes the entrance to the larynx in front, and during swal- 

 lowing of food or water its flexibility allows it to be pushed 

 back over the aperture like a lid, so as to close it hermetically, 

 and thus prevent any foreign matter obtaining admission 

 during the accomplishment of this act. When the act is 

 completed, the resiliency of the cartilage, together with the 

 contraction of a muscle connecting it with the hyoid bone 



