MO THE PNEUMOGASTRIC NERVE. 



OF THE TENTH PAIR, THE PAR VAGUM, OR PNEUMOGASTRIC NERVE. 



The pneumogastric nerve arises by six or eight filaments from the 

 groove between the olivary and restiform bodies below the glosso-pha- 

 ryngeal, and, like it, may be traced to the vesicular material of the floor 

 The tenth air ^ tne fo urtn ventricle. It first presents a small ganglion, 

 or pneumogas- and soon after a second, nearly an inch in length, called the 

 plexus gangliformis. The nerve then descends the neck in 

 the sheath of the carotid vessels, and in its course differs on the right 

 and left sides respectively. On the right side it passes between the sub- 

 clavian artery and vein, descending toward the stomach and solar plexus 

 on the posterior portion of the oesophagus ; on the left it enters the chest 

 nearly parallel with the left subclavian, and passes to the stomach and 

 solar plexus along the anterior portion of the oesophagus. 



The chief branches of the pneumogastric are the auricular, the pharyn- 

 geal, the superior laryngeal, the cardiac, the inferior laryngeal or recur- 

 rent, the anterior pulmonary, the posterior pulmonary, the cesophageal, 

 and the gastric. 



The pneumogastric presents several plexuses in its course, and, even 

 when distributed on the stomach, exhibits flat, membraniform ganglia. 

 It supplies three great classes of organs : 1st. The digestive, as the pha- 

 rynx, oesophagus, stomach, liver; 2d. Respiratory, as the larynx, trachea, 

 lungs ; 3d. Circulatory, as the heart and great vessels. It associates it- 

 self intimately with the sympathetic, and aids it in forming several great 

 plexuses. 



At its root the pneumogastric is sensory, but in its trunk it possesses 

 a double function, arising from its intermingling with other nerves, as the 

 spinal accessory and sympathetic. Though the trunk, if irritated, gives 

 rise to pain, we are not, under ordinary circumstances, conscious of indi- 

 cations, as, for example, in the act of breathing, in which we do not per- 

 ceive the necessity of respiration, except the access of the air be too long 

 delayed. The pharyngeal branch is the chief motor nerve of the pharynx 

 and palate. The superior laryngeal is the sensory nerve of the larynx, 

 the inferior laryngeal being the motor. Considered along with the spi- 

 nal accessory, the pneumogastric presents an analogy to a spinal nerve ; 

 the accessory constituting the anterior or motor root, and the pneumo- 

 gastric, with its ganglion, the sensory root. 



The pneumogastric nerve was formerly regarded as taking an influen- 

 tial part in the action of the stomach during digestion. The precise na- 

 ture of its agency in this, respect has been already alluded to. In addi- 

 tion, it may be remarked that probably through this nerve is the sensa- 

 tion of hunger conveyed to the mind. 



