NERVUS FACIALIS OF ALBINO MOUSE 119 



In different series there are some differences in the arrange- 

 ment of these nerves. In one series the ramus auricularis vagi 

 is composed of a single large bundle, in another the ramus cu- 

 taneus facialis is composed, after its origin, of two bundles, 

 and there are apparently some differences in the number of 

 fibers which interchange. However, the essential arrangement 

 is constant and as described above. 



Immediately after its origin the ramus cutaneus facialis passes 

 from the medial to the lateral side of the posterior auricular 

 nerve. From here it extends anteriorly and laterally above the 

 external auditory meatus until the point of the attachment of 

 the cartilage of the auricle to the side of the cranium is reached. 

 At this point it enters the auricle, extending upward and anteri- 

 orly along the medial side of that part of the auricle which bounds 

 the pouch-like concha laterally (figs. 14A and 14B). It gives 

 off branches in this region which supply the skin and hair follicles. 

 Other branches pass dorsally beyond the concha and supply the 

 skin of the posterior third of the lateral surface of the auricle. 



The ramus auricularis vagi sends a small branch to supply a 

 part of the external auditory meatus and the tympanic membrane, 

 this branch containing a few fibers from the facial (fig. 13D). 

 Otherwise the nerve supply of the tympanic membrane is the 

 same as that given by Wilson ('07, '10-' 11). After the origin 

 of the branch to the tympanic membrane the auricular branch 

 of the vagus passes along the cranial side of the concha. It 

 supplies this area of skin and its terminal branches pass dorsally 

 beyond the concha to supply the anterior two-thirds of the 

 lateral surface of the auricle (fig. 14). 



These two nerves have been followed with great care from their 

 origin to their place of ending. Each, in that part of its course 

 where it is related to the auricular cartilage, passes between the 

 cartilage and the skin, a location where there are no muscle 

 fibers. Branches of each have been followed to their final end- 

 ing and have been found to end in a plexiform manner immedi- 

 ately under the epithelium or around the hair follicles. It is 

 safe to conclude that they are both common sensory in function 

 for the supply of the skin and hair of the auricle. 



