310 S. WALTER RANSON 
of the vagus has divided into the laryngopharyngeal (d’’) and 
the esophageal branch (d’) and in the angle between these 
branches lies the sympathetic trunk (e). After the laryn- 
gopharyngeal branch has separated from the esophageal branch 
the sympathetic trunk runs with the latter (d’, e, fig. 7). The 
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Fig. 6 Section of the vagus at the level indicated by 6, figure 1. a, ramus 
descendens hypoglossi; 6, N. hypoglossus; c, ramus thoracoabdominalis vagi; 
d’, N. esophageus; d’’, N. laryngopharyngeus; e, truncus sympatheticus. Osmic 
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thoracoabdominal ramus and esophageal branch of the vagus, 
the descendens hypoglossi and the sympathetic trunk all run 
caudad in a common sheath. 
3. The vagus nerve in the thoracoabdominal cavity. The esoph- 
ageal branch and the descendens hypoglossi leave the vagus in the 
neck, but the sympathetic trunk and the thoracoabdominal 
vagus occupy the same sheath as they lie ventro-lateral to the 
lower cervical vertebrae under the plastron. Here they each 
develop a ganglion, the middle cervical ganglion of the sympa- 
thetic and the thoracoabdominal ganglion of the vagus (fig. 2). 
Serial sections show that the two nerves, though contained in a 
common sheath, are separated by a connective tissue septum. 
