Cog HILL, Cranial Nei-ves of Amblystoma. 249 



The trigeminus arises by a single large root of motor and 

 sensory fibers. It bears the Gasserian ganglion and the 

 ganglion of the ophthalmicus profundus which form a common 

 ganglionic mass with the ganglion of the anterior division of the 

 lateralis VII root. 



The r. ophthalmicus superficialis VII arises as an indepen- 

 dent nerve wholly from the ganglion of the anterior division of 

 the lateralis VII root, and innervates the supra-orbital group of 

 sense organs. The r. buccalis arises wholly from the same 

 ganglion and forms a part of the t. infraorbitalis. It inner- 

 vates the infraorbital groups of sense organs. The r. mentalis 

 VII forms into an internal and an external division. The exter- 

 nal innervates the oral group of sense organs ; the internal, the 

 gular group. The main nerve sends fibers also to the sense 

 organs over the region of the suspensorium. 



The r. ophthalmicus profundus V gives out two ciliary 

 nerves, which vary greatly in their peripheral relations, and 

 several cutaneous branches in the region of the optic nerve. 

 One of the latter meets the fourth nerve but does not anasto- 

 mose with it. The lateral and mesial terminal branches of the 

 nerve innervate the skin mesially and anteriorly from the eye ; 

 the ventral terminal branch anastomoses by two divisions with 

 the r. palatinus VII. The general cutaneous portion of the 

 infra-orbital trunk arises from the Gasserian ganglion and inner- 

 vates the region posteriorly and ventrally of the eye, and the 

 projecting fold of the posterior part of the upper lip. The 

 sensory part of the mandibular trunk arises from the same 

 ganglion. It sends one cutaneous branch caudad over the 

 suspensorium, others to the skin about the angle of the jaw, 

 and one to the inner epithelium of the cheek. One branch is 

 closely associated with the r. mentalis externus along the ramus 

 of the jaw, but does not fuse with it. Another branch anas- 

 tomoses with the r. alveolaris VII within the alveolar canal of 

 the mandible. The terminal cutaneous branches innervate the 

 skin covering the m. mylohyoideus. The general cutaneous 

 fibers which are found in the r. jugularis VII are derived from 

 the third root of the vagus and are distributed to the skin cov- 



