THE PHARYNX. 317 



pharynx, between the upper and middle constrictors, and 

 is inserted into the cornu and posterior margin of the thy- 

 roid cartilage. 



Function. To raise, dilate, and shorten the pharynx, so 

 as to receive the food. It will also elevate the larynx. 



The middle coat consists of cellular tissue, called the 

 pharyngeal aponeurosis, which is stronger along the mid- 

 dle line where it gives attachment to the constrictor mus- 

 cles, than elsewhere, and is the connecting structure be- 

 tween the outer or muscular, and mucous or internal 

 coat. This coat, being a continuation of that lining 

 the cavity of the mouth, will be considered in connection 

 with it. 



Cavity of the Pharynx. Dissection. Make an incision 

 through the middle tendinous line on the back part of the 

 pharynx, and this cavity will be exposed. In front will 

 be seen the velum and uvula, and opening into it will be 

 noticed seven foramina; at its upper part are the two pos- 

 terior nares, on each side of these are the Eustachian tubes, 

 in front is the isthmus of the fauces, and below we see the 

 glottis, and the commencement of the oesophagus. The 

 Eustachian tubes are found at the posterior part of the in- 

 ferior turbinated bone, and as just stated, on each side of 

 the nares. Their mouth is circular, and large enough in 

 most cases to admit the end of the little finger. They lead 

 to the ear, and conduct the air from the pharynx into the 

 cavity of the tympanum. Their direction is upwards, out- 

 wards, and backwards to the tympanum, occupying in their 

 course the pterygoid fossa, and having in two-thirds of 

 their extent a thick cartilaginous structure, the balance 

 being composed of bone. These tubes are lined by the 

 mucous membrane continued from the pharynx, and when 

 this is inflamed they become thickened and obstructed, this 

 being a frequent cause of deafness. 



Blood-vessels, (Fig. fS.) The arteries supplying the 

 pharynx are the superior and inferior pharyngeal, tHe for- 

 mer a branch of the internal maxillary, the latter a branch 

 of the external carotid. The palatine and superior thyroid 



