20(5 



MK.MOIRS OP THE NATIONAL ACADEMY OP SCIENCES. 



edge of .the vaginal process and sometimes quite within its folds. Below this nodosity there can 

 sometimes be seen a second swelling with the same evidences of a suture. Then, again, there are 

 many skulls hi which the first nodosity is present, and the process is terminated by a truncated 



extremity, as if a piece had been attached to it, but had been 

 lost in preparation; and, finally, in some few eases the styloid 

 composed of three distinct pieces was observed, as described by 

 Thomas. 



There can be little doubt that the part spoken of by Thomas 

 as the " hyoid prolongation " is the tympanohynl element of 

 Flower, which, there is good reason to believe, is variable in 

 length. There is also little doubt that not uncommonly there 

 is a distinct ossification intervening between the lower end of 

 the true stylohyal element and the ceratohyal piece, or small 

 cornu of the hyoid, which can not be accounted for upon any 

 hypothesis other than that it is the strict homologue of the 

 missing epihyal so constant in the lower forms. It would be a 

 matter of no little interest to determine the frequency of its 

 occurrence in the various races of mankind. (See Figs. 38 

 and 39.) 



Passing now to the hyoid bone proper, we have to consider 

 the several elements of which it is composed. As is well known, 

 it is generally described in works on human anatomy as con- 

 sisting of a single u -shaped bone, formed by the union of five 

 These are known as the body and the greater and lesser cornua. Although there does 



th. 



th. 



Fio. 38. Hyoidean apparatus of man. [After 

 Thomas.] 



pieces. 



not appear to be absolute unanimity of opinion among anatomical writers regarding the particular 



time of life when these elements coossify, we can not do better than to 



quote here the statements made by the leading anatomical authorities 



upon this point. 



Among the German anatomists Meckel, in his Manual of Anatomy, 

 says: 



" The hyoid hones, or the hyoid bone, forms an arch which is convex forwards. 

 It is situated behind and below he maxillary, beneath the root of the tongue and 

 the upper part of the neck. It is generally considered a single bone, and is divided 

 into a central portion, or body and four horns, two upon each side; but as these 

 parts remain distinct throughout life it is better to admit five distinct bones, a 

 middle and four lateral. The inferior hyoid bones, or the greater coruua of I lie 

 hyoid, often vary considerably in form and size upon the different sides in the same 

 subject. They articulate with the central piece by a iibro-cartilaginous mass and 

 sometimes unite in the latter periods of life in one bone." 



Henle, in his Human Anatomy, says: 



"The great horns of the hyoid bone can also be connected with the body by joint. Many hold this to be the rule." 



Hyrtle, in his Lehrbuch der Anatomic des Memchen, says, quoting from Meckel : 



"The os hyoid is divided into central or body andtwo lateral cornua, which parts, an they are united by movable 

 articulation or by synchondrosis, and often in old age not coossified, can be considered as so many different or sepa- 

 rate hyoids." 



Gegenbaur, in his Lehrbuch der Anatomie des Menschen, says : 



"The great cornua often coossify with the body." 



Hartmann, in his Handbuch der Anatomie des Menschen, says : 



" The five parts of the hyoid bone articulate by movable joint at the small horns and with synchomlrosis at the 

 large horns. In old age these parts are ofttimes anchylosed." 



Krause, in his Menschliche Anatomie , says: 



" The great horns are united with the body by rapsular ligament, and the joint is an amphiarthrosis. Very often 

 it is only a synchondrosis." 



Fio. 39 Styloid process of man. 



[After Thomas.] 



