228 SPECIAL ANATOMY. 



surfaces on the sides of the Cricoid surfaces plane. Ligament, capsular 

 with shining parallel fibres synovial capsule. The crico-thyroid articu- 

 lations are all Arthodial. TRAXS.] 



c. Ligg. crico-arytcenoidea unite the arytcenoid cartilages with the plate of 

 the cricoid, at the posterior internal surface ; strong but loose. [Synovial 

 capsule.] The arytcenoid cartilages are moveable in all directions, but 

 especially outwards and inwards. 



d. Ligg. arytceno-epiglotticum, inside the folds of mucous membrane 

 from the anterior surface of the arytcenoid cartilages to the borders of the 

 epiglottis. 



4. Vocal cords, ligg. vocalia s. glottidis, s. thyreo-arytcenoidea, are four liga- 

 ments which extend between the angle of the thyroid (on the posterior sur- 

 face) and the anterior surface of the arytcenoid cartilages, passing from before 

 to behind through the midst of the cavity of the larynx. There are, right and 

 left, a superior and an inferior. The triangular fissure between those on the 

 right and those on the left side is called the glottis s. rima glottidis, is before 

 narrow, behind roundish, at that part formed by cartil. cricoid. and cartt. arytce- 

 noid., and is not capable of being completely closed (Mayer). 



a. Ligg. vocalia inferiora, are thick roundish cords attached before to the 

 angle of the thyroid, behind to the anterior tubercle of the arytcenoid car- 

 tilages ; covered externally by m. thyro-arytcenoideus, internally by closely- 

 applied mucous membrane, they meet below at the ligg. crico-thyreoid. 

 lateralia. 



b. Ligg. vocalia superiora, less strong than the last, above them in the 

 middle of the larynx, under the Epiglottis, not quite horizontal. Below 

 them the mucous membrane forms a sac, ventriculus Morgagni; above 

 they meet in Kg. arytceno-epiglotticum. 



464. C. The muscles of the Larynx. The whole larynx is 

 moveable : Mm. sterno-, omo-, thyreo-hyoidei, sterno-thyreoidei, 

 &c. (see before) ; the separate cartilages are moved by the fol- 

 lowing muscles : 



1. Crico-thyreoidei, two short, thick, triangular muscles on the anterior sur- 

 face of the larynx, behind m. sterno-thyreoid and thyroid gland, in contact below 

 with the last, above m. crico-arytcenoid. later the internal borders separated by 

 a quadrangular space. Or. : the anterior surface of the cricoid cartilage. Ins. : 

 the inferior border and internal surface, and the anterior border of the inferior 

 Cornua of the thyroid cartilage. Use : to approximate the cricoid and thyroid 

 cartilages, elongating the glottis and stretching the vocal cords. 



2. Crico-arytcenoidei postici, triangular, on the posterior surface of the cricoid, 

 covered before by this, behind by the mucous membrane of the Pharynx. Or. : 

 from the posterior surface of the cricoid cartil. Ins. : external angle of basis 

 cartil. arylcen. Use : to separate the two vocal cords of either side from one 

 another, widening the posterior part of the rima glottidis. 



3. Crico-arytcenoidei laterales, two flat, rhomboidal-shaped muscles. Situ- 

 ation : on the posterior wall of the Larynx (internal surface), oblique upwards 

 and backwards ; closely connected internally with thyreo-arytcen. Or. : the 

 lateral part of the superior border of the cricoid cartilage. Ins. : external angle 

 of the arytcenoid cartilages. Use. : to draw the external angles of the arytcenoid 

 cartilages forwards ; the anterior angles with the vocal cords pass inwards, 

 and thus contract the rima glottidis. 



i 



