104 TOBACCO : ITS HISTORY. 



glossus, beneath which it passes to be distributed 

 to the mucous membrane of the tongue, and to the 

 mucous glands of the mouth and tonsils. Among 

 its numerous branches are the pneumogastric, the 

 sympathetic, and the lingual. 



The pneumogastric descends the neck within 

 the sheath of the carotid vessels, diverging in its 

 course ; on the right passing between the subcla- 

 vian artery and vein to the posterior mediastinum, 

 then behind the root of the lung to the oesopha- 

 gus, which it accompanies to the stomach, lying 

 on its posterior aspect. The left enters the chest 

 parallel with the left subclavian artery, crosses 

 the arch of the aorta, and descends behind the 

 root of the lung, and along the anterior surface 

 of the oesophagus to the stomach. 



The internal branches of the superior cervical 

 ganglion of the sympathetic nerve are, 1°, Pha- 

 ryngeal, filaments communicating with the pha- 

 ryngeal plexus upon the middle constrictor 

 muscle. They are also, 2*', Laryngeal to com- 

 municate with the external laryngeal nerve ; and 

 ajong branch descends to the thorax, and is dis- 

 tributed to the heart, the superior cardiac nerve. 



