NERVES OF THE DOGFISH 337 



6. The ramus mandibularis V 



This ramus of somatic sensory and visceral motor fibers de- 

 rives its sensory elements mostly from the mesial end of the 

 gasserian ganglion. Most of its ganglion cells are intracranial. 

 Its fibers pass directly laterally through and around the poste- 

 rior border of the maxillary part of the ganglion, and bending 

 posteroventrally around the dorsolateral border of the palato- 

 quadrate bar break up into two divisions, a large dorsal motor 

 branch supplying the adductor mandibulae muscle, and a ven- 

 tral division that divides into an anterior branch supplying the 

 skin of the ventral side of the lower jaw anteriorly, and a poste- 

 rior branch that innervates the first ventral constrictor muscle 

 and supplies the skin ventral to this muscle (figs. 15 to 17, 20 

 to 22, 24, 33, 35, 51 to 53, md.). The anterior part of the first 

 ventral constrictor muscle is innervated exclusively by the 

 ramus mandibularis V, but in the posterior part where its fibers 

 mingle indistinguishably with those of the second constrictor 

 muscle, there is evidently innervation also from the truncus 

 hyomandibularis VII. This ventral motor branch of the man- 

 dibularis also innervates a part of the adductor mandibulae. 



From the dorsal border of the main trunk of the ramus man- 

 dibularis shortly after leaving the ganglion there are given off a 

 few (three or four) small branches, which break up into numerous 

 small twigs, motor elements supplying the levator palatoquad- 

 rati and spiracular muscles and sensory fibers supplying the skin 

 dorsolaterally in the region of the spiracle (fig. 35, lvp-q.). From 

 the main mandibular trunk, as it is passing around the lateral 

 border of the palatoquadrate bar, there is given off from its 

 ventral side a small nerve. This follows the main nerve abound 

 to the ventral border of the bar of cartilage, but as the man- 

 dibular trunk turns posteriorly this small nerve bends antero- 

 ventrally along the lateral border of the palatoquadrate bar, 

 entering the lateral border of the posterior part of the pre- 

 orbital muscle, and furnishing the innervation of the latter (figs. 

 35 and 51, pro.). The writers do not find in any of the many 

 series of sections examined any anastomosis between the ramus 



