912 



THE LARYNX. 



inferior, and are arched in form. Bounded by the superior and inferior 

 vocal cords are two deep oval depressions, one on each side of the glottis, 

 named the sinuses, or ventricles, of the larynx ; and leading upwards from the 

 anterior parts of these depressions, external to the superior vocal cords, are 

 two small culs-de-sac, named the laryngeal pouches or sacculi. 



Fig. 637. PERSPECTIVE VIEW OF THE 

 PHARYNGEAL OPENING INTO THE LA- 

 RYNX PROM ABOVE AND BEHIND. 



The superior aperture has been much 

 dilated ; the glottis is in a moderately 

 dilated condition ; the wall of the pha- 

 rynx is opened from behind and turned 

 to the two sides. ], body of the hyoid 

 bone ; 2, small coi-na ; 3, great cornua ; 

 4, upper and lower cornua of the thyroid 

 cartilage ; 5, membrane of the pharynx 

 covering the posterior surface of the 

 cricoid cartilage ; 6, upper part of the 

 gullet ; 7, membranous part of the 

 trachea ; 8, projection caused by the 

 cartilage of Santorini ; 9, the same be- 

 longing to the cartilage of Wrisberg ; 10, 

 aryteno-epiglottidean fold ; 11, cut mar- 

 gin of the wall of the pharynx ; a, free 

 part of the epiglottis ; a', its lower 

 pointed part ; a", the cushion ; 6, 

 eminence on each side over the sacculus 

 or pouch of the larynx ; &', the ventricles ; 

 c, the glottis : the lines on each side 

 point to the margins or vocal cords. 



The superior vocal cords, also 

 called the false vocal cards, because 

 they are not immediately concerned 

 in the production of the voice, 

 are two folds of mucous membrane, 

 each of which forms a free cres- 

 centic margin, bounding the cor- 

 responding ventricle of the larynx, 

 the hollow of which is seen on 



looking down into the laryngeal cavity, from the superior vocal cords being 

 separated farther from each other than the inferior cords. 



The inferior or true vocal cords, the structures by the vibration of which 

 the sounds of the voice are produced, occupy the two anterior thirds of the 

 aperture of the glottis. These cor.ls are not mere folds of mucous mem- 

 brane, but are strengthened near their free margins by the elastic thyro- 

 arytenoid ligaments, and further out by the thyro-aryteuoid muscles. 

 The mucous membrane covering them is so thin and closely adherent as to 

 show the light colour of the ligaments through it. Their free edges, which 

 are sharp and straight, and directed upwards, form the lower boundaries of 

 the ventricles, and are the parts thrown into vibration during the pro- 

 duction of the voice. Their inner surfaces are flattened, and look towards 

 each other. 



The rima glottidis, an elongated aperture, situated, anteriorly, between 

 the inferior or true vocal cords, and, posteriorly, between the bases of the 

 arytenoid cartilages, forms when nearly closed a long narrow slit, slightly 



