250 PHYSIOLOGY OF CENTRAL NERVOUS SYSTEM. 



fibers to the gastric and pancreatic glands. Its sensory or afferent 

 fibers are distributed to the mucous membrane of the larynx, 

 trachea, and lungs, and to the mucous membrane of the esophagus, 

 stomach, intestines, and gall-bladder and ducts. These fibers 

 arise from cells in the ganglia on the trunk of the nerve, the gan- 

 glion jugulare and g. nodosum. The branches from these cells that 

 pass into the medulla terminate in the gray matter of the ala cinerea. 



The Eleventh Cranial Nerve (N. Accessorius) . This nerve is 

 usually described as arising by upper roots from the medulla, and 

 by a series of lower roots from the spinal cord as low as the fifth 

 to the seventh cervical segment. It is a motor nerve, supplying 

 fibers to the sternomastoid and trapezius muscles. The medullary 

 branches arise from the posterior portion of the dorsal motor 

 nucleus which gives origin to the vagus, while the spinal branches 

 originate from cells in the anterior horn of the gray matter of the 

 cord (Fig. 106). 



The Twelfth Cranial Nerve (N. Hypoglossus). This nerve arises 

 from the medulla in the furrow between the anterior pyramid and 

 the olivary body. It is a motor nerve, supplying the muscles of 

 the tongue and the extrinsic muscles of the larynx and hyoid bone. 

 Within the brain these fibers originate from a distinct nucleus 

 lying in the floor of the fourth ventricle near the mid-line (Fig. 

 106). 



