46 MORPHOLOGICAL TYPES 



The corresponding ventral root of the first segment is the 

 oculomotor (No. Ill), which supplies the following four eye- 

 muscles : superior, internal, and inferior rectus, and the 

 inferior oblique. It is also connected with the sympathetic 

 ciliary ganglion. 



The second or mandibular segment has as its dorsal root 

 the trigeminal (No. V, 2 and 3). This nerve is composed of a 

 superficial ophthalmic branch running forwards over the eye, 

 a maxillary branch in the upper jaw and a mandibular branch 

 in the lower jaw. These nerves are distributed to sense- 

 organs in the skin, and also to the muscles which move the 

 jaws. 



The corresponding ventral root of the second segment is 

 the trochlear (also called pathetic ; No. IV), which innervates 

 the superior oblique eye-muscle. 



The dorsal root of the third or hyoid segment is the facial 

 nerve (No. VII). It is made up of the following branches : — 



superficial ophthalmic, running forwards over the eye 

 in company with that of the trigeminal, and inner- 

 vating the supraorbital lateral-line organs ; 



buccal, running forwards beneath the eye and inner- 

 vating the infraorbital lateral-line organs ; 



hyomandibular, passing down behind the spiracle to 

 innervate the lateral- line organs of the lower jaw, and 

 the muscles of the hyoid arch ; 



palatine, innervating the taste-organs on the roof of the 

 mouth ; 



pretrematic, running down in front of the spiracle, 

 innervating sense-organs. 



The auditory nerve (No. VIII), which innervates the sense- 

 organs of the ear, is really an enlarged and specialised branch 

 of the facial nerve. 



The corresponding ventral root of the third segment is the 

 abducens (No. VI), which supplies the external rectus eye- 

 muscle. 



The dorsal root of the fourth segment is the glossopharyn- 

 geal (No. IX). It has a branch to the temporal region of the 



