THE OS HYOIDES. 
403 
to a tubercle on the postero-inferior side of the thyroid cartilage, 
to elevate it and the larynx, or to depress the os hyoides; and the 
hyo-epiglottideus from the hollow opposite to the neck, to the back 
of the epiglottis, drawing it from and enlarging the opening into 
the trachea. The spur or neck projects anteriorly from two to 
three inches in length, and penetrates into the root of the 
tongue; its sides are roughened to give attachment to the genio - 
hyo-glossi muscles at the inferior part of the tongue, drawing 
down the tongue within the mouth, and limiting its action. 
Attached by a perfect capsular ligament to the extremities of the 
body of the os hyoides, and rising from it somewhat obliquely, 
are two bones, termed the shorter cornua , or horns; they give a 
certain degree of motion to the body of the bone, and also attach¬ 
ment to some of the muscles which are lost in and constitute the 
body of the tongue. There is also a muscle, the transversalis , run¬ 
ning from the anterior tubercle of one of these cornua to the other, 
limiting the motion yet strengthening the action of these bones ; 
and also a more powerful muscle, the hyoideus parvus, mentioned 
by Percivall in his “Muscular System,” but not afterwards de¬ 
scribed by him, from the shorter cornu to the longer, occupying 
the whole of the triangular space between them, and confining or 
bringing them close together. 
United to the shorter cornua, and likewise by a proper capsular 
ligament, and constituting perfect joints, are the longer cornua , 
extending posteriorly and horizontally along the side of the 
pharynx, until they reach the petrous portion of the temporal 
bone. A little before this they begin to widen, and terminate in 
a kind of foot, the superior part or toe of which has a cartila¬ 
ginous union with the temporal bone, and to the heel or inferior 
portion of which are attached two important muscles. The first is the 
sterno-lhyro-hyoideus, and which arises even so low as the point 
of the sternum, and climbing up the neck above the sterno max - 
illaris, divides, about the middle of the neck, into three distinct 
bodies, yet united together by a slender tendon—the central one 
going to the lower border of the thyroid cartilage, and the lateral 
ones to the heels of the longer cornua of the os hyoides. Its 
use is to depress the os hyoides and larynx by drawing 
them downward and backward. 
The other muscle attached to this process is the hyoideus 
magtius (the hyoideus of Mr. Percivall). It arises from the heel 
of the cornu, and, as it proceeds along the side of the bone ante¬ 
riorly, its belly is divided, and forms a loop, through which 
passes one of the tendons of the digastricus. It has two in¬ 
sertions into the body of the os hyoides. This likewise draws the 
bone backward, or causes it to contract a little upon itself, and so 
helps to dilate the glottis. 
