THE NERVOUS SYSTEM. 197 



Pulmonary Branches. If the nerves are cut in the neck, the 

 respirations are markedly diminished, death finally occurring. 

 Galvanization increases the number; if strong may arrest it. 



(Esophageal Branches. Paralysis of these causes an inability 

 to swallow food, which remains in the gullet. It is finally vomited 

 by irritation of the tube. 



Gastric Branches. If the left nerve is cut during digestion, 

 secretion and motion at once cease; slightly irritated, it causes 

 glycosuria. 



After division, the bile becomes more fluid in character, the 

 formation of glycogen ceases, and purgatives have no longer any 

 effect. 

 Eleventh or Spinal Accessory. 



This is a motor nerve as well as supplying the larynx through 

 the laryngeals. 



Stimulation causes spasm of the sterno-maxillaris , mastoido- 

 humeralis, and cervical and dorsal trapezius. 



Division causes paralysis of these as well as shortness of breath, 

 from incoordination of muscles and inability to make a prolonged 

 vocal sound. 

 Twelfth or Hypoglossal. 



This is purely motor and division causes paralysis of the mus- 

 cles of the tongue and difficulty in mastication and deglutition. 



THE SPINAL CORD. 



The inferior motor roots emerge from the larger extremity of 

 the horn of gray matter on either side, and communicate with the 

 large multipolar motor cells found in groups in that situation. 



The superior or sensory roots enter the cord, immediately com- 

 municating with the tripolar sensory cells of the smaller extrem- 

 ity of the gray matter, which comes to the surface. 



Some of both the motor and sensory roots enter the columns 

 of the opposite side or lateral tracts, not all of the fibres thus pass- 

 ing up or down at the same point. 



Decussation of motor and sensory tracts. 



Most of the motor nerves cross to the opposite side at the me- 

 dulla, the nerves from the right side of the brain ending on the 

 left side of the body, and vice versa. Some of the motor roots 

 continue down the cord on the same side as the direct pyramidal 

 tract. 



