34 M. K. CHASE AND S. W. RANSON 



NOTES FROM THE LITERATURE ON THE HISTOLOGY OF THE 

 VAGUS AND ACCESSORY NERVES 



Gaskell ('86), working with osmic acid preparations from the 

 dog, found that the accessory nerve was made up of two portions : 

 a larger zone composed chiefly of large medullated fibers with a 

 few medium and small ones, and a smaller zone containing mainly 

 small medullated fibers with a few larger ones and much connec- 

 tive tissue. The fibers in the larger zone were derived from the 

 cervical rootlets. Those in the smaller zone came from the bul- 

 bar and highest cervical radicals and went by way of the in- 

 ternal branch of the accessory to join the vagus. Gaskell also 

 found bundles of small medullated fibers in the roots of the vagus 

 and glossopharyngeal nerves. He considers the small medullated 

 fibers in the roots of these three nerves as equivalent to the small 

 fibers in the anterior roots of the spinal nerves, that is, as pre- 

 ganglionic autonomic fibers. From the level of the nodose gan- 

 glion downward he found areas in the vagus in which no myehn 

 sheaths were present, and he correctly interpreted these areas as 

 bundles of non-meduUated fibers. He assumed that the small 

 preganglionic medullated fibers in the roots lost their myelin 

 sheaths in the nodose ganglion, and thought that they ended 

 there in connection with cells of a sympathetic nature. Gaskell 

 found that the medullated fibers left the vagus by way of the 

 pharyngeal, laryngeal, pulmonary, and cardiac branches; so that 

 very few were left in the vagus at the level of the esophageal 

 plexus. 



Molhant ('10) and Van Gehuchten and Molhant ('11), work- 

 ing with the vagus nerve in man and in the rabbit, found three 

 kinds of medullated nerve fibers : large, medium and small. The 

 large fibers with thick myelin sheaths occur chiefly in the pharyn- 

 geal branch of the vagus and in the laryngeal branches of the 

 recurrent nerve. Medium-sized fibers mixed with a few large 

 ones are found in the superior laryngeal. Fine medullated 

 fibers and some of medium size are found in the tracheal and 

 esophageal branches of the recurrent nerve and in the thoracic 

 vagus. Molhant, using the Cajal silver stain on the trunk of 



