168 VISCERAL ANATOMY. 



Describe the Vocal Chords. They are in two sets, the 

 Superior or False Vocal Chords, containing the superior thyro-arytenoid 

 ligaments, extend from the angle of the thyroid cartilage around to the 

 anterior surfaces of the arytenoids, and consist of two folds of mucous mem- 

 brane, each having a free crescentic margin. 



Inferior or True Vocal Chords, containing the inferior thyro-arytenoid liga- 

 ments, extend from the angle of the thyroid cartilage around to the ante- 

 rior angles of the bases of the arytenoids, and consist of two thin layers of 

 mucous membrane covering the ligaments named, each having the thyro- 

 arytenoideus muscle external and parallel to it. 



What is the Glottis ? The Glottis or Rima Glottidis is a narrow chink 

 or interval between the inferior vocal chords, formed by the projection into 

 the cavity of the larynx of these chords and the thyro-arytenoidei muscles. 

 Its greatest length is less than an inch, its greatest breadth about half an inch. 

 Its form is a narrow fissure of varying size. 



What is the Ventricle of the Larynx ? An oval depression on each 

 side of the larynx, between the true and false vocal chords, leading up to the 

 sacculus laryngis by a narrow opening. 



What is the Sacculus Laryngis ? A blind pouch situated in each 

 laryngeal wall at the level of the false vocal chord. It is of conical shape, 

 and contains 60 or 70 small mucous glands which secrete a fluid for the 

 lubrication of the true vocal chord. The sacculus is covered in by the 

 aryteno-epiglottideus inferior muscle internally, and by the thyro-epiglot- 

 tideus externally, both muscles compressing it to discharge its contents. The 

 Sacculus Laryngis is also called the Sinus of Morgagni, and the lower part 

 of the ventricle is sometimes named the Sac of Hilton. 



What class of Epithelium lines the Larynx ? Its mucous membrane 

 is covered with Ciliated Epithelium below the level of the superior vocal 

 chords, extending in front as high as the centre of the epiglottis. Over the 

 rest of the larynx is Squamous Epithelium. 



Describe the Laryngeal Muscles. They are 4 in number on each side 

 and one in the median line, viz. 



Crico-thyroid (2), from the front and side of the cricoid cartilage/ into 

 the lower and inner border of the thyroid.^ Action, to tilt the thyroid 

 cartilage forwards, thus elongating and making tense the vocal chords. 

 Nerve, superior laryngeal. 



Crico-arytenoideus Posticus (2), from the cricoid cartilage posteriorly, 

 into the posterior angle of the base of the arytenoid cartilage. Action, 

 to rotate the arytenoids outwards and open the glottis, while keeping the 

 vocal chords tense. Nerve, recurrent laryngeal. 



