MOKPHOLOGY OF CliANlAL ^IL'SCLES IN SUME VElITEJiUATES. 303 



iutennedius with gang, genie), IXth (gang, petros.), Xtli, 

 Xltli (gang, trunci vagi), Xlltli (gang, hypoglossi). 



This classification of the motor centres, as regards those of 

 voluntary muscles, followed v. AVijhe's theory of the moi*- 

 phology of the cranial muscles. It was also adopted by 

 Strong and by Herrick. 



According to Streeter the motor nucleus of the \^tli nerve 

 in man is developed in tiie lateral plate, and the nucleus 

 anibiguus of the Vllth, IXth, and Xth in the basal plate. 



Text-fig. 99. 



AV. 



npui Wt- 



Pig. eniljryo 15 mm., portion of longitudinal vertical section. 



The issuing fibres of the Vtli pass straight outwards like 

 those of the dorsal efi'erent fibres of the IXth, Xth, and 

 Xlth (medullary) ; whilst those of the Yllth, IXth, and 

 Xth, arising from the nucleus ambiguus, have a characteristic 

 curved path. The motor nucleus of the Vih is a hyper- 

 trophied representative of the dorsal motor nuclei of the 

 IXth, Xth, and Xlth (medullary), or the latter is represented 

 in the mesencephalic root of the Vth. 



Kappers showed that the original position of the Vllth, 

 IXth, and Xth motor nuclei is medio-dorsal, and that the 



