ANATOMY, PHYSIOLOGY, OF NERVOUS SYSTEM. 429 



parotid gland the nerves which control the secretion of the 

 same. 



Tenth. The vagi. The vagi or pneumogastrics are the 

 longest of the cranial nerves and their distribution widest. 

 They send branches to the pharynx, gullet, larynx, wind- 

 pipe, lungs, heart, stomach, and even read; the solar plexus 

 in the mesentery. They contain: First. Motor fibers for 

 the muscles of the pharynx, oesophagus and larynx, for the 

 muscular coat of the stomach and the muscles of the princi- 

 pal portion of the small intestine. Second. Inhibitory fibers 

 for the heart. Third. Sensory fibers for the throat, the 

 oesophagus and lungs. Fourth. Reflex fibers which affect 

 the process of inspiration and expiration. FiftJi. In man, 

 finally, it contains the depressor nerve (separate in the 

 rabbit) which runs from the heart to the brain and carries 

 sensory impulses to the brain. This depressor figures inte- 

 grally in the vascular supply of the body. 



Eleventh. The accessorii. The spinal accessory nerves 

 in reality arise from the cervical portion of the spinal cord, 

 but run into the skull alongside of the spinal cord, receiv- 

 ing a few fibers from the medulla and then pass out with 

 the pneumogastric nerves. Bach gives off a branch to the 

 pneumogastric nerve, while the main portion of the trunk 

 is distributed to the muscles of the shoulder. 



T^velfth. The hypoglossi. The hypoglossal nerves are 

 the motor nerves of the tongue and innervate all of the 

 muscles of the same. They carry, however, a few sensory 

 and vaso-motor fibers to the tongue. This nerve is of espe- 

 cial interest in the consideration of the process of mastica- 

 tion, and better still in the production of articulate speech. 



The Sympathetic System. 



The sympathetic system consists of two chains of ganglia 

 lying alongside the backbone and easily visible when the 

 chest and abdominal viscera are removed. Each chain con- 

 sists of twenty-four ganglia. In the coccygeal region the 

 two chains meet in a median - placed ganglion, making, 



