226 SPECIAL ANATOMY. 



461. 1. The Larynx, larynx s. organon vocis, the most 

 superior portion of the trachea, is a moveable canal formed of 

 seven cartilages, in the centre of the anterior superior region of 

 the neck, under the os hyoides, before the inferior part of the 

 pharynx (between fourth and sixth vert.). 



Shape : above, broader and three-cornered ; below, narrow and 

 cylindrical. 



Elements : cartilage, ligaments, muscles. 



a. Cartilages of the Larynx : Thyroid and Cricoid are true, 

 the rest, fibre-cartilages. 



462. 1. Thyroid cartilage, cartilago thyreoidea, occupies the greatest part 

 of the anterior and lateral walls, and consists of two oblong four-sided plates, 

 which are united at an acute angle, in the middle line, and the surfaces of 

 which are directed obliquely backwards and outwards. External surface. 

 In the male the angle projects more strongly forwards (Adam's apple) than 

 in the female, and before puberty, when it is more rounded. At the pos- 

 terior part of the external surface of each lateral plate we find above, a tu- 

 bercle, and below, a larger; between the two we perceive a linea obliqua, 

 before which m. thyro-hyoideus and behind which mm. constrictor infer, and 

 sterno-thyreoid. are situated; sometimes a foramen for Art. laryngea super. 

 Internal surface : a. At the angle are attached the vocal cords and mm. thyro- 

 arytcenoidei. b. The sides project out over the cricoid cartilage. The superior, 

 border is twisted, in the centre deeply excised, incisura thyreoidea, it looks 

 towards the hyoid bone and terminates at the sides with the great cornua. 

 Here is attached Membr. hyo-thyreoid. The inferior border, shorter than the 

 last, inclines towards the cricoid cartilage, serving for the attachment of m. 

 crico-thy redid., in the centre the lig. crico-thyreoid. ; is bounded externally by the 

 ksser cornua. The posterior border, slightly twisted, serves for the attach- 

 ment of mm. stylo-pharyngeus and pharyngo-staphylinus, leans on the vertebral 

 column. The horns, cornua, are oval elongations of the posterior borders, 

 directed inwards and backwards. The larger superior are in connection 

 with the hyoid bone by ligaments, the less inferior with the cricoid cartilage. 



2. The annular cartilage, cartil. cricoidea, thicker and more solid than the 

 other cartilages of the larynx, is circular, narrow before, broad behind (one 

 inch) and like an escutcheon, four-cornered. External surface. In front in 

 the centre under the skin ; serves laterally for the attachment of mm. crico- 

 thyreoidei, presents an articular process for the thyroid cartilage; behind, in 

 the centre a projection for muscular fibres of the pharynx; laterally, a depres- 

 sion for m. crico-arytcenoid. posterior. 



The internal surface is covered with mucous membrane. The inferior 

 border is completely circular, connected with the trachea by lig. crico-tracheale. 

 The superior border is irregular, before low, with two articular surfaces (for 

 the arytcpnoid cartilages'), behind (on the shield) placed higher. The shield 

 forms the inferior half of the posterior wall of the larynx. 



3. The arytaenoid cartilages, cartilagines arytcenoida s. pyramidales are two 

 moveable cartilages, standing, close to one another, vertically, upon the shield 

 of the mcoirf,and forming the superior part of the posterior wall of the larynx. 

 Below broad, above pointed, the anterior surface convex, narrow, grooved, 

 with the superior vocal cord ; the posterior surface concave and broad (for m. 



