THE MUSCLES OF THE PHARYNX 161 



tongue, and the intermediate to the whole length of the tongue, 

 some decussating across the median line. 



M. hyoglossus is flat and quadrate. Origin, whole length 

 of the great cornu and lateral part of the anterior surface of 

 the hyoid body; insertion, posterior half of the tongue, where 

 fibers spread forward and inward over the dorsum, joining 

 the styloglossus. The fibers from the hyoid body may be 

 called the basioglossus, those from the great cornu the kerato- 

 glossus. 



The chondroglossus is often described as a part of the above, 

 but is separated from it by the pharyngeal fibers of the genio- 

 hyoglossus. Origin, inner side of the base of the small cornu 

 and from part of the superior surface of the hyoid body; its 

 fibers end on the dorsum of the tongue near the middle line. 



M. Styloglossus. Origin, front of the styloid process near 

 the apex, and largely from the stylomaxillary ligament; insertion, 

 side and under part of the tongue as far as the tip, decussating 

 and blending with the hyoglossus and palatoglossus. 



The lingualis is the intrinsic tongue muscle, presenting 

 inferior, superior, transverse, and vertical fibers, with a median 

 fibrous septum. 



Nerves. Motor supply by the hypoglossal. 



Actions. Geniohyoglossus, hinder part protrudes the tongue, 

 front part retracts, middle part or nearly whole muscle depresses 

 and makes dorsum concave; in hemiplegia the sound fibers 

 push apex over to the paralyzed side. The hyoglossus and 

 chondroglossus retract, depress, and make the dorsum convex; 

 the styloglossus draws the tongue back, elevates the base, and 

 makes the dorsum concave. 



The Muscles of the Pharynx 



There are two layers an outer, called the constrictors, 

 three in number, with a transverse direction; an inner, called 

 the elevators, two in number, with a longitudinal direction. 



Inferior Constrictor (laryngopharyngeus). Origin, cricoid 

 cartilage at the lower and back part, the inferior cornu, oblique 

 line, and upper tubercle of the thyroid cartilage; some fibers 

 continue into it from the sternothyroid and cricothyroid muscles. 

 It unites with its fellow in the median line; its inferior fibers 

 are horizontal, and a few enter the longitudinal layer of the 

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