174 OUTLINES OF EqUlXE AK ATOMY. 



runs to the posterior crescentic margin of the hjoid bone. 

 This ligament fills the space between the superior cornu of 

 the cartilage and the alse, with the exception of the angle, 

 where it is deficient, and thns a foramen is formed through 

 wJiich the terminal ])ortion of the siijperior laryngeal branch of 

 the imeumogastric runs to supply the mucous membrane of 

 the larynx with exquisite sensibility. The external surface of 

 the thyroid alse is in contact with the thyro-hyoideus supe- 

 riorly ; thyro-pharyngeus supero-posteriorly ; crico-thyroi- 

 deus inferiorly ; between these the short portion of sterno- 

 thyro-hyoideus is attached. From the superior cornu the 

 posterior part of hyo-thyro-pharyngeus runs upwards. The 

 internal surface is superiorly covered by mucous membrane, 

 inferiorly by thyro-arytenoidei posticus and anticus (and is 

 in contact with crico-ary tenoideus lateralis) . The Epiglottis 

 has aptly been likened to a sage leaf, the base of which 

 is attached by elastic tissue to the internal surface of the 

 body of the thyroid, the apex is invested closely by mucous 

 membrane, and is free. It consists of yellow elastic car- 

 tilage, and the mucous membrane covering it presents 

 very large mucous gh.nds. To the anterior surface mucous 

 membrane proceeds from the base of the tongue, and by 

 removal of this centrally we shall expose 



Syo-eijiglottideus running from the posterior part of the 

 body of OS hyoides, directly backwards to the anterior sur- 

 face of the epiglottis. The base of the epiglottis on either 

 side is continued by a prolongation which runs in a back- 

 ward direction, connected by cartilaginous nodules (called 

 the cuneiform cartilages) to the arytenoid cartilages. The 

 posterior surface of the epiglottis is covered by mucous 

 membrane, and during the act of deglutition is brought 

 down over the glottal opening or entrance to the larynx. 



The cricoid cartilage, as its name indicates, is extremely 

 like a finger-ring. Its smallest part is anteriorly situated, 

 and from this it increases in size irregularly in a posterior 

 direction. The posterior part forms a flat hexagonal sur- 

 face, with a central ridge and four synovial articulatory 

 facets, two at the antero-inferior angles for articulation 

 mth the posterior acute angles of the thyroid alse, two at 

 the postero-superior angles for articulation with the ary- 

 tenoid cartilages. On either side of the central ridge is 

 attached a crico-arytenoideus posticus, while crico-aryte- 

 Tioideus lateralis originates from the posterior j^art of the 



