VOICE ANATOMY OF THE VOCAL APPARATUS. 459 



The respective action of the different muscles has been given in a 

 tabular form. 1 



Govern the Pitch of the Notes. 



w ' fp . , ... ( Depress the front of the thyroid cartilage on thecricoid and stretch 



2 the vocal ligaments; assisted by the arytenoideus and crico- 

 j ( arytenoidei postici. 



j Thyro-arytenoidei ( Elevate the front of the thyroid, and draw it towards the arytenoid, 

 Thyro-hyoidei ( relaxing the vocal ligaments. 



i L 



Govern the Aperture of the Glottis. 

 Crico-arytenoidei postici . . . Open the Glottis. 



11 



Crico-arytenoidei laterales ( Press together the inner edges of the ary- 



< I Arytenoideus tenoid cartilage, and close the glottis. 



The intrinsic muscles of the larynx receive their nervous influence 

 from the eighth pair (Fig. 198). Shortly after this nerve has issued 

 from the cranium it gives off a branch, called superior laryngeal, which 

 is distributed to the arytenoid and crico-thyroid muscles; and, after its 

 entrance into the thorax, it furnishes a second, which ascends towards 

 the larynx, and is, on that account, called recurrent or inferior laryn- 

 geal. It is distributed to the crico-arytenoidei postici, crico-arytenoidei 

 laterales, and thyro-arytenoid muscles. No ramification of this nerve, 

 according to M. Magendie, goes to the arytenoid, or crico-thyroid mus- 

 cles. In these views, he is supported by M. J. Cloquet 2 and by many 

 others. Other distinguished anatomists, however, maintain that the ary- 

 tenoideus muscle receives a branch from each of the inferior laryngeals. 

 Dr. Reid asserts, that he has repeatedly satisfied himself of the existence 

 of this arytenoid branch of the inferior laryngeal, and the dissection 

 is one, he says, which can leave no kind of doubt on the matter. 3 



In each animal species, the glottis has a construction corresponding 

 to the kind of voice; and, when it is examined in the living animal 

 the dog for example it enlarges and contracts alternately, the ary- 

 tenoid cartilages separating when the air enters the lungs, and approxi- 

 mating during expiration. 



To the trachea the larynx is attached by a fibrous membrane, which 

 unites the cricoid with the first ring of the trachea ; and, above, it is 

 connected with the os hyoides by a similar membrane the hyo-thyroid, 

 No. 2, Fig. 194, as well as by the thyro-hyoid muscle. 4 



2. PHYSIOLOGY OF VOICE. 



The production of voice requires, that air shall be sent from the lungs, 

 which, in passing through the glottis, throws certain parts into vibra- 

 tion, and afterwards makes its exit by the vocal tube, that is, by the 

 mouth and nasal fossae. Simple expiration does not, however, produce 



1 Carpenter's Human Physiology, 4th Amer. edit., 604, Philad., 1850. 

 8 Traite d'Anatomie Descriptive, ii. 622, Paris, 1816. 



3 Art. Par Vagum, by Dr. J. Reid, in Todd's Cyclopaedia of Anat. and Physiol., Parts xxvii. 

 and xxviii. p. 893, London, 1846-7. For an excellent description of the anatomy of the 

 vocal apparatus, see J. Bishop, art Larynx, Cyclop, of Anat. and Physiol., Lond., Sept., 1840. 



4 Willis, in Cambridge Philosoph. Transact, for 1832, iv. 323. 



