ON THE CETACEAN LARYNX. 3 
The crico-arytenoid, rather indistinctly divided into posterior and lateral 
portions, arises from the posterior surface of the cricoid below the level of its 
lateral process or horn, and is inserted into the lower part of the posterior face of 
the arytenoid. Running parallel with this muscle, close to its outer border, and 
inserted together with it, is the cerato-arytenoid, arising from the inner face of the 
posterior thyroid cornu, near its articulation with the cricoid. 
AS! Ar Le eal ----Fp. 
ec Te Lar SSWZ4S ae hg an ep. 
Ar-- -----& Ce aa i th. ar 
4 tr ar... ! ae 
BRR OAS as VEER SoS os 
Pe GN RD mmm TN Cr. 
Figs. 5 and 6. 
The same larynx from behind and from the right side. In Fig. 6 the right ala of the thyroid has been cut away. 
l.cr.a., lateral crico-arytenoid muscle. .cr.wr., posterior crico-arytenoid. The other letters as before. 
The inter-arytenoid is a very narrow, straight muscle, uniting the two ary- 
tenoid cartilages. 
The thyro-arytenoid, a thick, broad muscle, arises from the angle of the thyroid, - 
and is inserted into the prominent external border of the arytenoid. 
Thus the whole of the “ arytenoid” muscles, without exception, pass to the three 
arytenoid cartilages, and the arytenoid horns, herein called the supra-arytenoids, are 
destitute of muscular connections. 
After reflecting the ala of the thyroid, a very strong triangular ligamentous 
band, closely connected with the mucous membrane, is seen passing from the lower 
part of the epiglottis to the anterior process of the supra-arytenoid, and partly over 
the same to the true arytenoid: the extreme anterior part of the supra-arytenoid 
into which this is inserted is separated off as a cartilaginous nodule from the rest. 
Now I am inclined to think that this condition explains at least two points. 
Firstly, the main portion of the supra-arytenoid is now shown quite conclusively to be 
independent of the true arytenoid, and must from its position be taken as the structure 
which our Cartilages of SANTORINI represent in the form of a very degenerate rudi- 
ment. Secondly, the other rudimentary cartilages in the larynx of higher mammals, 
namely, the Cartilages of WRISBERG, seem to be likewise explicable as being identical 
with the separate portion of the supra-arytenoid involved in the ligamentous fold 
connecting the arytenoid with the epiglottis. In short, the Cartilages of Sanrorrnt 
and of WRISBERG represent remnants of the superior and inferior (anterior) portions 
of a once large Cetacean-like supra-arytenoid. 
