298 THE BIOLOGY OF THE FROG CHAP 



to the nasal chambers and anterior portion of the roof oi 

 the mouth. The second branch, the hyomandibular, runs 

 outward and then backward, around the auditory capsule, 

 passing over the columella, and, after receiving a branch 

 from the glossopharyngeal, runs outward, gives some twigs 

 to the ear and muscles of the lower jaw, and then divides 

 near the angle of the jaw into the mandibularis internus, 

 which runs forward close to the mandible, and the hyoideus, 

 which innervates the subhyodeus muscle and the skin in the 

 region of the throat. The seventh nerve, like the fifth, con- 

 tains both sensory and motor fibers. 



The eighth, or auditory, nerve is distributed entirely to the 

 inner ear. 



The ninth, or glossopharyngeal, nerve arises from the sides 

 of the medulla from a group of roots in common with the 

 vagus ; these roots emerge from the skull through a foramen 

 in the exoccipital external to the condyle and enter the large 

 jugular ganglion. Shortly after its emergence from this 

 ganglion the trunk of the glossopharyngeal bears a small 

 ganglionic swelling and then soon divides, the one branch 

 passing forward to join the hyomandibular division of the 

 facial, the other running forward in a sinuous course along 

 the floor of the mouth and innervating the mucous mem- 

 brane of the tongue and pharynx. 



The tenth (i^agus or pneumogastric'} nerve emerges from 

 the jugular ganglion generally by two trunks ; the small 

 anterior trunk, the ram its auricularis, is distributed to the 

 region of the tympanum ; the main nerve passes backward, 

 and, after giving off some small branches to the muscles 

 of the shoulder, becomes distributed to the larynx, esopha- 

 gus, stomach, lungs, and heart. Both the glossopharyngeal 

 and vagus contain sensory and motor fibers. The accessories, 

 which is a small branch supplying the cucullaris muscle 



