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ESSENTIALS OF ZOOLOGY 



maxillo-mandibular divides into the maxillary and mandibular. 

 The maxillary supplies the lower eyelid and the skin of the 

 side of the head and upper jaw ; it is sensory. The mandibular 

 supplies the skin and the muscles of the lower jaw, and contains, 

 therefore, sensory and motor fibres. 



VI. The abducent arises from the floor of the medulla, and 

 leaves the skull by the prootic foramen to supply the external 

 rectus muscle and also the retractor bulbi muscle of the eye. 



VII. The facial lies at its origin close to the trigeminal on 

 the side of the medulla, and its ganglion, moreover, is fused 

 with that of the VHIth nerve. It passes from the skull by 

 the prootic foramen. It divides into two branches : the 



|' Hypoglossal 



Gastric 



Pulmonary and 



cardiac 

 Laryngeal 



FIG. 109. Cranial nerves. 



palatine, directed to the mucous membrane of the roof of the 

 mouth ; and the hyomandibular, which is connected to the 

 IXth, runs along the posterior wall of the middle ear and 

 Eustachian tube, and divides into the mandibular branch, 

 supplying the floor of the mouth, and the hyoid branch, which 

 goes to the muscles of the hyoid. It is a mixed nerve. 



VIII. The auditory nerve enters the auditory capsule and 

 is the nerve of the internal ear. 



IX. The glossopharyngeal is the nerve of the first branchial 

 cleft of the tadpole. In the adult it gives off a branch which 

 crosses the columella to join the hyomandibular branch of the 

 Vllth, and then passes on to supply the muscles and mucous 

 membrane of the floor of the mouth. It is a mixed nerve. 



X. The vagus, or pneumogastric, arises on the side of the 

 medulla in company with the IXth, and both nerves pass from 

 the skull by a common foramen in the exoccipital. In the 

 larva it is the nerve of the posterior branchial clefts and the 



