374 



COMPARATIVE ANATOMY 



The vocal cords extend between the thyroid and the arytenoids, 

 and the mucous membrane above them becomes evoluted laterally 



FIG. 280. DIAGRAM TO ILLUSTRATE THE METAMORPHOSIS DURING DEVELOP- 

 MENT OF THE FIRST TO FIFTH VISCERAL SKELETAL ARCHES (I V) IN 

 MAN. 



From the proximal end of the first arch (Meckel's cartilage) arise two of the 

 auditory ossicles, the malleus and incus (ml and in), p, pinna ; pr, mastoid 

 process of skull. 



From the second arch (hyoid) arise proximally the styloid process (p.s), 

 distally the anterior (lesser) cornu of the hyoid (c.a) and a portion of the basi- 

 hyoid (b.$). By far the greater portion of this arch becomes the stylo-hyoid 

 ligament (l.g). [Concerning the stapes (at) cf. p. 134.] 



The third (first branchial) arch gives rise to the greater part of the body 

 (b.s) of the hyoid, and the posterior or greater cornu of the hyoid (c.p). 



The fourth (second branchial) arch gives rise to the anterior (upper), and 

 the fifth (third branchial) to the posterior (lower) segment of the thyroid 

 cartilage (th', th"). The arytenoid cartilage (ar) is probably a derivative of the 

 fifth arch, cr, cricoid cartilage ; tc, cartilage triticea, connecting the hyoid and 

 thyroid ; tr, trachea. 



to form the laryngeal pouches, one (more rarely both) of which may 

 undergo special development and in Anthropoids may reach such a 

 large size that it serves as a resonance cavity. In other Monkeys, 



