836 PHYSIOLOGY. 



Cortical Connections. The sensory ascending path of the ninth 

 nerve ends in the inferior part of the central region of the cortex 

 and in the immediate neighborhood of the posterior part of the sec- 

 ond and third frontal convolutions. 



The nucleus ambiguus gives off neuraxons to form its motor 

 root. The sensory neuraxons arise from the jugular and petrosal 

 ganglions and arborize about two sensory nuclei in the medulla 

 oblongata. The lower sensory end nucleus produces an elevation on 

 the floor of the fourth ventricle, and is called the ala-cinerea. The 

 upper nucleus is also connected with sensory neuraxons of glosso- 

 pharyngeal nerves, while the lower portion of this nucleus is in rela- 

 tion with the vagus. The second nucleus is called the vertical 

 nucleus, the fasciculus solitarius, the combined descending root of 

 the pneumogastric and glosso-pharyngeal nerves, or the respiratory 

 bundle. This respiratory tract extends from the olive down the 

 spine to the eighth cervical nerve. This respiratory bundle of Gierke 

 may associate the nuclei coordinating the various respiratory muscles. 

 The glosso-pharyngeal nerve arises by a half-dozen cords from the 

 restif orm body and goes through the jugular foramen into the vagus, 

 where it has a small ganglion : the jugular. As it emerges from the 

 jugular foramen there is developed the petrosal ganglion, or gan- 

 glion of Andersch. 



Nerve of Jacobson. This same ganglion gives origin to the nerve 

 of Jacobson. It enters the cavity of the tympanum by way of an 

 opening in its floor, where it divides into three filaments. These are 

 distributed, one to the round window, another to the oval window, 

 and the third to the lining membrane of the Eustachian tube and 

 tympanum. 



Physiology. The ninth is a mixed nerve. Its* motor properties 

 are distributed to the middle constrictors of the pharynx and the 

 stylo-pharyngeus muscle. 



The most important sensory function of the glosso-pharyngeal 

 is the part which it plays in the role of the sense of taste. 



The ninth nerve has an action upon the blood-vessels of the 

 tongue that is identical with that of the chorda tympani. If the 

 glosso-pharyngeal be cut and its peripheral end stimulated, the 

 tongue becomes a livid red. 



Pathology. In man there are no clear cases recorded where 

 there have been uncomplicated affections of the glosso-pharyngeal. 



