TSE CRANIAL NERVES. 509 



sense ; but according to Gegenbaur (Lankester), A, 515, it is developed like an ordinary 

 cranial nerve. 



It springs from the ceptalic part of the Eminentia auditoria, traverses the ental audi- 

 tory meatus, and is distributed to the sensory organs of the labyrinth or " internal " ear. 



§ 1388. (IX) Nervus glossopharyngeus, N. gph.., the glossopharyngeal nerve. — Fig. 

 116 ; PI. II, Fig. 3. Gray, A, 658 ; Quain, A, 1, 554 ; Stowell, 1. 



The origins of this nerve and of tlie vagus and accessorius are associated so as to form 

 a series extending caudad from the Eminentia auditoria for a considerable distance along 

 the lateral aspect of the cervical myelon. "We have not examined these origins in detail, 

 and the reader is" referred to the figures and descriptions of Stowell. As has been stated 

 elsewhere, the points of origin cannot be defined accurately until the ectal features of the 

 " medalla " are more satisfactorily understood. 



The nerve has a ganglion (Gng. petrosum), emerges through the Fm. jugulare, and is 

 distributed, in man, to the base of the tongue, the soft palate and the pharynx. 



§ 1389. (X) Nervus vagus, N. v., the vagus or pneumogastric nerve. — Fig. 116 ; PI. 

 II, Fig. 3. Gray, A, 660 ; Quain, A, I. 556 ; Stowell, 1. 



This nerve, remarkable alike for its distribution, its accessions from other (motor) 

 sources, and its numerous and peculiar functions, arises just caudad of the glossopha- 

 ryngeus by several funiculi, which, according to Stowell, form two series, dorsal and 

 ventral. As stated under the glossopharyngeal, we have not fully examined the origin, 

 and the student is referred to the figures and descriptions of Stowell. 



The nerve presents a ganglion (Gng. jugulare, ganglion of the root), in the proximal 

 end of the foramen of exit, and about 15 mm. peripherad of the foramen another, the Gng. 

 inferius or the ganglion of the trunk (Fig. 107 ; Stowell, 1). 



Relations of the Ganglia. — The Gng. jugularis is connected by anastomotic filaments 

 with the N. facialis (VII), glossopharyngeus (IX), accessorius (XI) and sympathicus. 

 The ganglion of the root is connected with the N. glossopharyngeus (IX), accessorius 

 (XI), hypoglossus (XII), and sympathicus ; (Stowell, 1). 



Besides the connections just named, the vagus furnishes the following branches : NN. 

 pharyngeus, laryngeus superior, laryngeus recurrens, rami cardiaci, rami pulmonares, 

 gastricus dorsalis and gastricus ventralis (Fig. 103, 107 ; §§ 1040, 1041). It also gives 

 many anastomotic filaments to the sympathicus (§ 1041 ; Stowell, 1). 



§ 1390. (XI) Nervus accessorius, N. ac, the accessory or " spinal accessory " nerve. — 

 Fig. 116 ; PI. II, Fig. 8. Gray, A, 686 ; Quain, A, I, 564; Stowell, 1. 



This nerve has a peculiar and extensive origin by funiculi scattered along the lateral 

 aspect of the metencephalon and cervical myelon, from just caudad of the origin of the 

 vagus to a point opposite the 6th or 7th cervical nerve. 



The trunk enters the cranium by the Fm. magnum, and then associates itself with the 

 vagus and glossopharyngeus to emerge through the Fm. jugulare. In man it is distrib- 

 uted to the trapezius and stemo-mastoid muscles, and also, by the fibers which join the 

 vagua, to the heart. 



§ 1391. (XII) Nervus hypoglossus, N. hpg., the hypoglossal nerve. — Fig. 116 ; PI. II, 

 Fig. 3. Gray, A, 646 ; Quain, A, I, 565. 



Arises by several (10-15) funiculi from the ventral aspect of the metencephalon just 

 laterad of the caudal half of the Area elliptica (oliva ?). (The difficulty in the homology 

 of this area is referred to in §§ 1161, 1188.) 



The funiculi are very slightly attached and apt to be torn oflf with the pia. The trunk 

 escapes through the Fm. condylare, and is distributed, in man, chiefly to the muscles of 

 the tongue. 



This nerve has much the aspect of the ventral root of a myelonal nerve. 



