Stowell.] 132 [July ig_ 



numerous filaments are directed dorsad, by whose anastomoses and union 

 with N. synipathicus is formed the oesophageal plexus wliich embraces the 

 entire length of the thoracic oesophagus. Caudad of the ramuli given to 

 the pulmonary plexus, 15-20 mm. caudad of the caudal border of the 

 arch of A. aorta, N. vagus sinister divides into sinistral or lateral and dex- 

 tral or mesal rami (Fig. 9, 46) which lie respectively upon the sinistral 

 dorsum and venter of the adjacent oesophagus. The lateral ramus trends 

 dorso-caudad, and 50-60 mm. peripherad of its origin it unites with the 

 lateral ramus of N. vagus dexter in a median line upon the dorsum of the 

 oesophagus, to constitute a single dorsal trunk for about 25 mm. (Fig. 9, 

 47). Numerous anastomotic filaments from the two rami of N. vagus 

 sinister and the rami of N. vagus dexter interlace in the oesophageal plexus 

 from which filaments are given to the muscular tissue and mucous mem- 

 brane of the oesophagus. The united dorsal trunk i^erforates the dia- 

 phragm and enters the abdomen as the gastric nerve. 



The mesal ramus of N. vagus sinister trends ventro-caudad, and 20-25 

 mm. peripherad of its origin is joined by its dextral homologue (Fig. 9, 

 48), and these two mesal rami constitute a united ventral trunk which lies 

 in the caudal mediastinum upon the venter of the oesophagus and perfo- 

 rating the diaphragm near the meson, lies on the venter of the cardia (Fig. 

 13). A slight twig connects the tAvo mesal rami 2 mm. peripherad of 

 their origins. From the thoracic portion of the ventral trunk anastomotic 

 filaments are given to its homologue in the formation of the oesophageal 

 plexus. 



The thoracic portion of N. vag-us dexter lies ventrad of A. sub- 

 clavia and mesad of A. slernalis; at the caudal border of A. subclavia it 

 bends slightly dorsad to pass mesad of V. vertebralis at its iu'iction with 

 V. innominata, it continues laterad of the trachea, entad of V. azygos and 

 dorsad of the root of the right lung. As the main trunk enters the thorax 

 it sustains intimate relations through anastomotic twigs with N. cardiacus 

 magnus, N. cardiacus minor and the inferior cervical ganglion of N. 

 synipathicus (Fig. 10). 15 mm. caudad of A. subclavia a considerable 

 ramus is directed meso-caudad and accompanies a large ramus detached 

 entad of V. azygos ; these cardiac rami pass meso-veutrad around the base 

 of the right pulmonary artery and to the right auricle (Px. cardiacus ectalis). 

 Three or four ramuli are given ofi between A. subclavia and V. azygos 

 whose ramifications interlace the plexus of the trachea and oesophagus. 

 From the 12-14 mm. of the trunk dorsad of the lung, numerous filaments 

 are directed mesad and ventrad to join the pulm,onary plexus (Fig. 9). 

 Caudad of this point and opposite the bifurcation of its sinistral homologue 

 the dextral nerve bifurcates into lateral and mesal rami (Fig. !), 4!)); cau- 

 dad of the bifurcation the lateral ramus trends dorso-caudad until it joins 

 its sinistral homologue already described. The mesal ramus gives re- 

 current ramuli cephalad to the dextral border of the pulmonary plexus. 

 Several other anastomotic filaments are detached from the ramus between 

 the root of the lung and the union with its fellow which terminate in the 

 oesophageal plexus (Fig. 9). 



