378 THE NERVE SYSTEM 



foramen it grooves the lower border of the petrous 

 portion of the temporal bone. 



THE PNEUMOGASTRIC NERVE. The tenth, vagus, 

 or pneumogastric is both motor and sensor. Its 

 apparent origin is by twelve to fifteen filaments 

 below, and in the line of the origin of the ninth; its 

 deep origin is from a nucleus in the lower part of the 

 fourth ventricle. It passes through the jugular foramen 

 in the same sheath with the spinal accessory, a par- 

 tition separating them from the ninth, and develops 

 the ganglion of the root of the vagus. Emerging from 

 the foramen, it forms the ganglion of the trunk of the 

 vagus. 



The ganglion of the root (ganglion jugulare) is gray 

 in color and spherical, its diameter about two lines. 

 It has branches of communication with the accessory 

 part of the spinal accessory, with the petrous ganglion 

 of the ninth, with the facial, and 'with the superior 

 cervical ganglion of the sympathetic. 



The ganglion of the trunk (ganglion cervicale) is 

 larger, of a reddish color, and cylindrical form. Its 

 surface is crossed by the accessory portion of the 

 eleventh, and it communicates with the hypoglossal, 

 the upper two cervical, and the sympathetic nerves. 



The vagus then descends between the internal 

 carotid artery and the jugular vein to the thyroid 

 cartilage, then between the vein and the common 

 carotid to the root of the neck; where it enters the 

 thorax and gives off branches to the heart (cardiac 

 plexuses), lungs (pulmonary plexuses), and esophagus; 

 it then passes through the esophageal opening in the 

 diaphragm to enter the abdominal cavity where it 

 gives off branches to the solar plexus, the stomach, 

 liver, spleen, kidneys, suprarenal glands, and pan- 

 creas. 



THE ELEVENTH PAIR. The eleventh, or spinal 

 accessory, consists of si spinal portion and an accessory 



