1881.] -■--* [Stovvell. 



15 mm. caudad ot G. jugulare and dorsad of the origin of A. carotidea 

 interna, N. vagus receives a second ganglionic enlargement, ganglion 

 inferiiis, ganglion of the trunk (Fig. 5, 1.), This ganglion has a fusi- 

 form outline 5-8 mm. in caudo-cephalic diameter and 2 mm. in dorso- 

 ventral; it is of a pinkish color; is located ectad of (superlicial to) and 

 dorso-caudad of the closely-apposed superior cervical ganglion of N. sympa- 

 thicus, to which it is very intimately related through anastomotic filaments; 

 its cephalic extremity is apposed to the middle of the superior cervical 

 ganglion. G. inferius does not embrace or involve the main trunk of N. 

 accessorius; it is however joined at its dorso-cephalic border by a large 

 ramus given off from N. accessorius just peripherad of Px. gangliformis 

 (Fig. 5, lJi)\ it is the superficial origin of a lai'ge ramus of N. vagus, viz., 

 N. laryngeus superior; it communicates with N. glosso-pharyngeus (IX) 

 (Fig. 5, 17), N. accessorius (XI) (Fig. 5, 1^), N. hypoglossus (XII) (Fig. 

 5, 13), with the spinal nerves NN. vertebrales, in the loop which connects 

 the first and second cervical nerves, and with N. sympathicus (entad of 

 Px. gangliformis). 



In the cervical region N. vagus continues caudad from G. inferius asso- 

 ciated with N. sympathicus in the sheath of A. carotidea primitiva. In 

 the cephalic 20 mm. the trunk lies dorso-laterad of A. carotidea externa 

 and A. carotidea primitiva, being concealed within the arterial sheath by 

 the artery and by V. jugularis interna. As the nerve approaches A. oc- 

 cipitalis (?)* it lies laterad of A. carotidea primitiva and crosses the venter 

 of A. occipitalis (?) at its origin; it resumes its dorso-lateral relation 5-8 

 mm. caudad of A. occipitalis (?) until it enters the thorax. The trunk of 

 N. vagus in its cervical region caudad of G. inferius gives off several ramuli 

 which anastomose with ramuli of N. sympathicus to constitute a more or less 

 dense plexus around the trachea and oesophagus; this is especially marked 

 in the caudal portion of the cervical region. The distinctive courses of the 

 sinistral and the dextral nerves in the thorax require separate descriptions. 



The principal rami of the cervical portion ofN. vagus are Rm. 

 auricularis, N. pharyngeus, and N. larj^ngeus superior. 



lini. aiii'icularis, is a large anastomotic branch and has its superficial 

 origin in the dorso-ental border of G. jugidare; its course is curved dorso- 

 laterad and cephalad, and it enters the periotic bone, follows a groove along 

 the dorso-caudal border of the tympanic bulla, traverses the petrous por- 

 tion of the bone and enters aqueductus Fallopii at a point 2 mm. centrad 

 of the origin of chorda tympani; a portion of Rm. auricularis continues to 

 the opening where it meets the dorsal branch of N. facialis, to be distributed 

 to the ear. A considerable fasciculus crosses N. facialis and maybe traced 

 to the cochlea (Fig. 5, .5). 2 mm. peripherad of its origin Rm. auricularis 

 receives a considerable twig from N. glosso-pharyngeus (IX), and about 



* This artery, 25 mm. caudad ot foramen of exit and dorsad, or 1-.3 mm. dorso- 

 cephalad of A. thyreoidea superior, seems to be allied to A. princeps cervicis. 

 There are some objections to tliis liomology, but the mea!:urenients given in the 

 text identify it beyond question. 



