76 LABORATORY DIRECTIONS 



a. The superficial opthalmic branch of the trigeminal Is 

 joined by a similar branch of the seventh nerve to form a large 

 trunk. It passes anteriorly on the dorsal part of the median 

 wall of the orbit, penetrates the cartilage of the skull, and Is 

 distributed to the dorsal side of the head. 



b. The infraorbital nerve, made up of the maxillary branch 

 of the trigeminal and the buccal branch of the seventh, Is a 

 large white band passing under the eye on the floor of the orbit. 

 It ends In several branches. The maxillary fibers Innervate 

 the skin and the ampullae on the ventral side of the head. 



c. The mandibular branch arises ventral to the Infraorbital 

 and passes along the posterior wall of the orbit to supply muscles 

 of the lower jaw and gill arches, and also to innervate the sense 

 organs of the skin. 



VII. Facial. — This nerve Is both motor and sensory. Its 

 origin with the fifth nerve has already been mentioned. It 

 divides Into three branches. 



a. The superficial opthalmic is bound in the same sheath 

 with the similar branch of the fifth, and with it, goes to the sense 

 organs of the head, supplying part of the lateral line organs. 



b. The buccal branch of the seventh and the maxillary branch 

 of the trigeminal compose the infraorbital trunk, as has already 

 been mentioned. The buccal also supplies part of the lateral 

 line organs. 



c. The hyomandibular hra.nch.lies just under the skin posterior 

 to the spiracle. Trace It back toward the brain. It innervates 

 the sense organs of the head, the muscles of the hyold arch, the 

 floor of the mouth and the tongue. 



VIII. Auditory. — This arises with the fifth and seventh 

 and supplies the ear. It Is a sensory nerve. 



IX. Glossopharyngeal. — The ninth nerve arises from 

 the medulla posterior to the eighth and leaves the skull at the 

 posterior-lateral corner. It passes through the auditory capsule 

 and then divides and goes to the gill region. It Is both motor 

 and sensory. 



X. Vagus. — This nerve originates from the side of the 

 medulla, posterior to the ninth, by several roots. It Is a large 

 nerve and widely distributed. After passing through the 

 posterior wall of the skull it divides Into many branches to 



