Fig. 91. CRAKIAL NERVES OF A HUMAN EMBRYO, 10.2mm. long. (His.) 2 f. 



The cranial nerves are indicated by Roman, the spinal nerves by Arabic numerals. 



c. h, cerebral hemisphere ; th, thalamencephalon ; m.b, mid-brain; MX, maxillary process; Mn, 

 mandibular arch ; Hi/, hyoid arch ; the facial nerve is seen to send a branch (chorda tympani) across 

 the byomandibular cleft ; G.g, Gasserian ganglion ; c.g, ciliary ganglion ; r, vestibuhr, and c, cochlear 

 part of auditory ; g.p, ganglion petrosum of glossopharyngeal : g.j, ganglion jugulare of vagus ; an 

 anastomosis is seen between these ; g.tr, ganglion trunci of vagus ; F, ganglion described by Froriep as 

 belonging to the hypoglossal ; r.d, ramus descendens of hypoglossal ot otic vesicle. The eye is also 

 represented, and a part of the heart. 



Fig. 92. DIAGRAM SHOWING THE CENTRIPETAL AND CENTRIFUGAL ROOTS OF THE CRANIAL NERVES OF 



THE SAME EMBRYO. (His. ) 



The places of exit of the nerves are marked by dotted circles or ovals. The efferent nerves (///., 

 IV, mV, VI, VII, part of IX, XI, and XII], are seen to arise within the nerve centre from groups^of 

 neuroblasts ; the afferent fibres (V.s, VIII, v and c, most of IX, and X), pass a certain distance in- 

 wards, and for the most part also caudal wards in the nerve-centre, and there end. The ganglion rudi- 

 ments from which they have grown are not shown here. They will be found in the preceding figure. 



