284 Journal of Comparative Neurology. 



it and the m. adductor mandibulae. Here another little coarse 

 fibered twig is given off for this muscle, and a little farther 

 cephalad the r. mandibularis V divides into two branches, a 

 dorsal and a ventral. The dorsal branch retains the original 

 position ; the ventral one runs down external to Meckel's carti- 

 lage, between it and its investment of membrane bones, then 

 turns inward around the ventral side of the cartilage to join the 

 r. mandibularis externus VII, which at this level runs along the 

 inner side of Meckel's cartilage. This ventral branch includes 

 all of the remaining coarse fibers of the r. mandibularis V. 

 These motor fibers with a few fine, (sensory) ones now run up 

 between Meckel's cartilage and the r. mandibularis VII to join 

 the small bundle of fine fibers which runs along the dorsal side 

 of the mandibularis VII and which has already been described 

 as coming from the mandibularis V in the earlier anastomosis. 

 The mixed motor and general cutaneous nerve thus formed 

 runs for some distance cephalad along the dorsal surface of the 

 r, mandibularis VII, then turns inward into the isthmus. The 

 sensory fibers innervate the skin of this region, the motor 

 fibers the mm. genio-hyoideus and intermandibularis, anasto- 

 mosing behind with the r. hyoideus VII. The remainder of 

 the ventral branch meanwhile has wedged in between Meckel's 

 cartilage and the r. mandibularis externus VII, the cartilage 

 being external and the mandibularis externus internal to it. 

 The two nerves do not mix. The trigeminal nerve gives off 

 numerous branchlets from this point cephalad for the skin of 

 the mandible. 



The dorsal branch of the r. mandibularis V continues to 

 run forward internal to the outer lamella of the dentary bone, 

 and farther toward the tip of the mandible running farther ven- 

 trally so as to lie dorsal to Meckel's cartilage, crossing over it 

 to lie close to the r. mandibularis externus VII. We have, 

 then, in the alveolar canal near the tip of the mandible the 

 Meckel's cartilage lying adjacent to the outer lamella of the den- 

 tary bone and a wide space mesially of the cartilage containing 

 the ventral branch of the r. mandibularis V in its ventral part, 

 the r. mandibularis externus in its central part, laterally 



