CRANIAL NERVES. 



157 



ficial and a deep 1 branch, a maxillary (2nd division), and a 

 mandibular (3rd division). 



The first of these arises separately, like a dorsal root of a spinal 

 nerve, while the other two represent primitively a single branch, 

 corresponding to the mandibular, from which the maxillary grows 

 out secondarily. 



O Jyffir,KT ,3 4 .5 6 



FIG. 129. CRANIAL NERVES OF Anguis ft- 



G, Gasserian ganglion, from which proceed the three branches of the trigeminal, V", 

 V b , and Vc : behind it is seen a sling-like commissure of the sympathetic (Sy 

 and Co), which connects the trigeminal with the vagus-group (IX, X) : from 

 this commissure arises a sympathetic ganglion (Gg), as well as a long cord (Sym) 

 passing to the second sympathetic ganglion, Gg l ; VII a , VII b , the facial nerve 

 appearing through two separate apertures ; f> connection between the palatine 

 branch of the facial and the maxillary division of the trigeminal ; *t, points of 

 entrance of the maxillary and ophthalmic divisions respectively of the trigeminal 

 into the nasal capsule ; Mm, Mm, branches of the mandibular branch to the 

 masticatory muscles ; GX, ganglion of the vagus ; Li, inferior laryngeal nerve ; 

 p, superior laryngeal ; Hi, intestinal branch of the vagus ; XII, hj'poglossal (the 

 two first spinal nerves) ; 3 to 6, third to sixth spinal nerves ; 0, auditory capsule ; 

 Seap, scapula ; A, eye ; 7), D l . lacrymal and posterior part of Harderian gland. 



The fact that in many Vertebrates the trigeminal arises by two 

 separate roots indicates its double nature, as does also the fact 

 that, contrary to the general rule, all three divisions do not unite in 

 a single ganglion (the Gasserian), but each main branch may be 

 provided with an independent ganglion. 



In all Vertebrates, the first division of the trigeminal, 

 with its deep (naso-ciliary) and superficial branch, supplies the 

 integument of the forehead and snout, as well as the inteeni- 



o * o 



mentary coverings of the orbit and certain parts of the eye- 

 ball. It is entirely sensory. 



The second division of the trigeminal, which is also a 

 sensory nerve, is connected with the facial, and extends first 

 along the floor of the orbit, then passes to the upper jaw, supplying 

 the teeth, and finally, as the infraorbital branch, perforates the 



1 In Fishes and Amphibia the deep branch forms an independent twig ; in higher 

 forms it is bound up with the superficial branch as the naso-ciliary nerve. 



