2o6 ALUS. [Vol. XVIII. 



ternus, as it passes internal to the suprapharyngobranchial of 

 the first arch, bends somewhat sharply forward and downward 

 around that element. The muscle here lies between the glosso- 

 pharyngeus and first vague nerves, and between the efferent 

 arteries of the first and second arches. It is innervated by a 

 branch of the glossopharyngeus that arises from the truncus of 

 that nerve close to its ganglion. 



The posterior internus runs downward, backward and mesially, 

 external to the dorsal end of the anterior internus, but internal to 

 all the external levators. It is inserted on the dorsal surface of 

 the infrapharyngobranchial of the third arch, the surface of in- 

 sertion lying at about the middle of the piece, between the artic- 

 ular surfaces of the second and third epibranchials, and immedi- 

 ately lateral to the longitudinal ridge on the dorsal surface of the 

 infrapharyngobranchial. The muscle thus lies, at its insertion, 

 between the nerve and artery of the second arch and the same 

 structures of the third arch. It is innervated by a branch of the 

 first vagus nerve that arises from the posterior surface of the 

 truncus not far from the ganglion of the nerve. 



The externus of the first arch runs downward, backward and 

 mesially, and is inserted by a tendinous end on the dorsal surface 

 of the suprapharyngeal process of the first epibranchial, near its 

 dorso-mesial end. The muscle lies, in its course, immediately 

 internal to the ligament that connects the first arch with the side 

 wall of the skull, internal to the external levator of the second arch, 

 and external to the anterior internus. It lies, at its insertion, 

 posterior to the glossopharyngeus, and is innervated by a small 

 branch that arises from that nerve not far from the branch that 

 innervates the anterior internus. 



The externus of the second arch lies, at its origin, immediately 

 external to that of the first. It runs decidedly backward, ex- 

 ternal to all the levator muscles it crosses, and is inserted by a 

 tendinous end on the mesial edge of the suprapharyngeal process 

 of the second epibranchial, near the middle of the length of that 

 process. It lies, at its insertion, between the first and second 

 vagus nerves ; and is innervated by a small branch of the ramus 

 posttrematicus of the former nerve. The muscle was always 

 found double toward its origin, the dorsal part being inserted, not 



