THE PHARYNGEAL REGION 395 



Applied Anatomy. The fibrous septum which exists between the two halves of the tongue 

 is almost complete, so that the anastomosis between the two lingual arteries is not very free, 

 a fact often illustrated by injecting one-half of tlrj tongue with colored gelatin, while the other 

 half is left uninjected or may be injected with gelatine of a different color. 



This is a point of considerable importance in connection with removal of one-half of the 

 tongue for cancer, an operation which is now frequently resorted to when the disease is strictly 

 confined to one side of the anterior portion of the tongue. If the mucous membrane is divided 

 longitudinally exactly in the middle line, the tongue can be split into halves along the median 

 raphe without any appreciable hemorrhage, and the diseased half can then be removed. 



Actions. The movements of the tongue, although numerous and complicated, may be under- 

 stood by carefully considering the direction of the fibres of its muscles. The Geniohyoglossi 

 muscles, by means of their posterior fibres, draw the base of the tongue forward, so as to pro- 

 trude the apex from the mouth. The anterior fibres draw the tongue back into the mouth. The 

 whole length of these two muscles, acting along the middle line of the tongue, draw it down- 

 ward, so as to make it concave from side to side, forming a channel along which fluids may 

 pass toward the pharynx, as in sucking. The Hyoglos.';! muscles depress the tongue and draw 

 down its sides, so as to render it convex from side to side. The Styloglossi muscles draw the 

 tongue upward and backward. The Palatoglossi muscles draw the base of the tongue upward. 

 With regard to the Intrinsic muscles, both the Superior and Inferior lingualis tend to shorten 

 the tongue, but the former, in addition, turn the tip and sides upward so as to render the dorsum 

 concave, while the latter pull the tip downward and cause the dorsum to become convex. The 

 Transverse lingualis narrow's and elongates the tongue, and the Vertical lingualis flattens and 

 broadens it. The complex arrangement of the muscle fibres of the tongue, and the various 

 directions in which they run, give to this organ the power of assuming the various forms neces- 

 sary for the enunciation of the different consonantal sounds. 



5. The Pharyngeal Region (Figs. 306, 307). 



Inferior constrictor. Superior constrictor. 



Middle constrictor. Stylopharyngeus. 



Palatopharyngeus. ) ,. N 



c i u r (See next section.) 



Salpingopharyngeus. ) v 



Dissection (Fig. 306). In order to examine the muscles of the pharynx, cut through the 

 trachea and oesophagus just above the sternum, and draw them upward by dividing the loose 

 areolar tissue connecting the pharynx with the front of the vertebral column. The parts being 

 drawn well forward, apply the edge of the saw immediately behind the styloid processes, and 

 saw the base of the skull through from below upward. The pharynx and mouth should then 

 be stuffed with tow, in order to distend its cavity and render the muscles tense and easier of 

 dissection. 



The Inferior constrictor (m. constrictor pharyngis inferior], the most superficial 

 and thickest of the three Constrictors, arises from the side of the cricoid cartilages, 

 in the interval between the Cricothyroid muscle in front and the articular facet 

 for the thyroid cartilage behind; from the oblique line on the side of the ala of 

 the thyroid cartilage, the cartilaginous surface behind it, nearly as far as its posterior 

 border, and from the inferior cornu. From these origins the fibres spread back- 

 ward and inward, to be inserted into the fibrous raphe in the posterior median 

 line of the pharynx. The inferior fibres are horizontal, and continuous with the 

 fibres of the oesophagus; the rest ascend, increasing in obliquity, and overlap 

 the Middle constrictor. 



Relations. The Inferior Constrictor is covered by a thin membrane which surrounds the 

 entire pharynx, the buccopharyngeal fascia (fascia buccopharynyea). Behind, this fascia is in 

 relation with the vertebral column and the prevertebral fascia and muscles; laterally, with the 

 thyroid gland, the common carotid artery, and the Sternothyroid muscle; by its deep surface, 

 with the Middle constrictor, the Stylopharyngeus, Palatopharyngeus, the fibrous coat and 

 mucous membrane of the pharynx. The internal laryngeal nerve and the laryngeal branch 

 of the superior thyroid artery pass near the upper border, and the inferior, or recurrent laryngeal 

 nerve, and the laryngeal branch of the inferior thyroid artery, beneath the lower border of this 

 muscle, previous to their entering the larynx. 



