68 ANATOMY OF THE HEAD AND NECK. 



separation into two parts is marked in the tongues of cer- 

 tain birds and reptiles. 



The lingual artery will be found resting upon the genio- 

 hyo-glossus muscle; it gives a branch to the dorsum of the 

 tongue, and is continued forward to its apex under the 

 name of the ranine artery. 



Upon the hyo-glossus muscle the gustatory nerve will be 

 seen ; this is a branch of the inferior maxillary trunk of 

 the fifth nerve; it anastomoses with small branches of the 

 hypoglossal, and is distributed to the mucous membrane 

 and papillae of the tongue. 



The hypoglossal nerve also crosses the hyo-glossus muscle, 

 and, after penetrating the genio-hyo-glossus, is continued 

 forward to the apex of the tongue in the substance of that 

 muscle. It supplies the muscular structure of the tongue. 



The glosso-pharyngeal nerve passes under the posterior 

 border of the Iryoglossus muscle, and supplies the dorsum 

 and lateral mucous membrane of the tongue, the tonsils, 

 and the fauces. 



LARYNX. 



The tongue should now be separated from the larynx without 

 injuring the epiglottis; the hyoid bone should remain attached to 

 the larynx. The larynx should be extended, and made fast to the 

 table by means of pins ; the pharynx and extrinsic muscles should 

 be dissected away from its cartilages and from the hyoid bone. 



The hyoid bone is connected with the thyroid cartilage 

 of the larynx by a membrane called the thyro-hyoid mem- 

 brane, which includes the entire space intervening between 

 the upper border of the thyroid cartilage and the upper 

 border of the hyoid bone; this membrane is perforated by 

 the superior laryngeal nerve and the superior laryngeal 

 artery. 



The CRICO-THYROIDEUS MUSCLE is a triangular muscle, 

 and the largest of the special muscles of the larynx ; it 

 arises from the front and lateral part of the cricoid car- 

 tilage, and passes outward and backward, to be inserted 

 into the external and internal surfaces of the lower border 

 of the tnVroicl cartilage. 



The CRICO-ARYTENOIDEUS POSTTCUS MUSCLE arises from 

 the depression on the side of the vertical ridge of the cricoid 

 cartilage posteriorly ; its fibres converge and are inserted 

 into the muscular process of the arytenoid cartilage. 



The ARYTENOIDEUS MUSCLE covers in and unites the pos- 



