262 



MUSCLES AND FASCIAE. 



and the mucous membrane of the mouth. By its internal surface, with the tonsil, 

 the Superior constrictor, and the Hyo-glossus muscle. 



The Palcdo-glossus or Constrictor Istlimi Faucium, although one of the muscles 

 of the tongue, serving to draw its base upwards during the act of deglutition, is 

 more nearly associated with the soft palate, both in its situation and function ; 

 it will, consequently, be described with that group of muscles. 



Nerves. The Palato-glossus is supplied by the palatine branches of Meckel's 

 ganglion; the Lingualis, by the chorda tympani; the remaining muscles of this 

 group, by the hypoglossal. 



Actions. The movements of the tongue, although numerous and complicated, 

 may easily be understood by carefully considering the direction of the fibres of the 

 muscles of this organ. The Genio-hyo-glossi, by means of their posterior and 

 inferior fibres, draw upwards the hyoid bone, bringing it and the base of the tongue 

 forwards, so as to protrude the apex from the mouth. The anterior fibres will 

 restore it to its original position by retracting the organ within the mouth. The 

 whole length of these two muscles acting along the middle line of the tongue 

 will draw it downwards, so as to make it concave from before backwards, forming 

 a channel along which fluids may pass towards the pharynx, as in sucking. The 

 Hyo-glossi muscles draw down the sides of the tongue, so as to render it convex 

 from side to side. The Linguales, by drawing downwards the centre and apex 

 of the tongue, render it convex from before backwards. The Palato-glossi draw 

 the base of the tongue upwards, and the Stylo-glossi upwards and backwards. 



5. PHAKYNGEAL KEGION. 



Constrictor Inferior. Constrictor Superior. 



Constrictor Medius. Stylo-pharyngeus. 



Palato-pharyngeus. 



Fig. 156. Muscles of the Pharynx. External View. Dissection (fig. 156). In order 



to examine the muscles of the 

 pharynx, cut through the trachea 

 and oesophagus just above the 

 sternum, and draw them upwards 

 by dividing the loose areolar tis- 

 sue connecting the pharynx with 

 the front of the vertebral column. 

 The parts being drawn well for- 

 wards, the edge of the saw should 

 be applied immediately behind 

 the styloid processes, and the 

 base of the skull sawn through 

 from below upwards. The 

 pharynx and mouth should then 

 be stuffed with tow, in order to 

 distend its cavity and render the 

 muscles tense and easier of dis- 

 section. 



The Inferior Constrictor, 

 the most superficial and 

 thickest of the three con- 

 strictors, arises from the 

 side of the cricoid and thy- 

 roid cartilages. To the 

 cricoid cartilage it is at- 

 tached in the interval be- 

 tween the Crico-thyroid, in 

 front, and the articular facet 

 for the thyroid cartilage be- 

 hind. To the thyroid car- 

 tilage, it is attached to the oblique line on the side of the great ala, the carti- 



