398 



MAMMALIAN ANATOMY 



rod, to form a bony swing which supports the root of the tongue. 

 At each end of the transverse bar, a rod extends backward at right 

 angles and joins the larynx, the expanded upper end of the trachea, 

 or windpipe. The hyoid bones can be felt in life at the upper part of 

 the neck, in the anterior angle formed by the neck and the under part 

 of the jaw. They are attached by muscles to the skull, the lower jaw, 

 the larynx, and the sternum. 



FIG. 314. 



THE SKELETON OF THE CAT. 



The larger jointed rod (Fig. 315) is arched forward and slants 

 inward and upward. It is composed of four elements : an upper elon- 

 gated piece of cartilage known as the tympano-hyal, which forms the 

 union to the skull ; a second longer slender bar, the stylo-hyal ; a 

 shorter third piece, the epi-hyal ; and a small quadrate terminal ossicle, 

 the cerato-hyal. The transverse bar is called the basi-hyal, or body of 

 the hyoid. The posterior elements which support the thyroid cartilage 

 of the larynx are known as the thyro-hyals. The different elements 

 of the hyoid apparatus are joined together by intervening pieces of 

 cartilage which vary in size according to the age of the specimen. 



The tympano-hyal (Figs. 315, 316) is an elongated, flattened piece 

 of cartilage, the upper end of which is received into a pit in the 



