250 NERVOUS SYSTEM. [sect. 121. 



even into the central cavity (Todd and Bowman, i., pp. 75, 76; 

 Herbst, tab.iv., figs. 1 and 2). 



§ 121. Cerebral Nerves. — The sensitive and motor nerves, arising 

 from the brain, agree so closely with the spinal nerves, that a short 

 description of them is sufficient, while the specialities of the higher 

 nerves of sense will be afterwards considered along with the organs 

 of the senses. As regards their roots, as well as their course and dis- 

 tribution, the motor cerebral nerves, the third, fourth, sixth, seventh, 

 and twelfth pair present quite the same relations as the motor roots 

 and muscular branches of the spinal nerves, with the single excep- 

 tion, that by communications with sensitive nerves, some sentient 

 fibres, destined for the muscles, are mingled with all of these 

 nerves. It is worthy of remark, that, according to Volkmann, 

 the small root of the hypo-glossus of the calf, which is provided 

 with a ganglion, excites motorial effects. The signification of this 

 occurrence of ganglionic globules in motor nerves has not hitherto 

 been made out. Probably, simple fibres with peripheral distri- 

 bution arise from them, exactly as -in the spinal ganglia; at auy 

 rate, it shows that ganglia are not necessarily restricted to sensitive 

 nerves. The fifth, ninth, and tenth nairs resemble the spinal nerves 

 in so far as they all contain motor and sensitive elements. In the 

 trigeminus, the small root contains principally motor thick tubes ; 

 the large, many fine fibres. The Gasserian ganglion contains 

 numerous larger and smaller ganglion-globules, of 0-008'" to 

 0*030'", with nucleated sheaths, and, according to what I have 

 observed in small mammalia and in man, presents the same rela- 

 tions as a spinal ganglion, i.e., it allows the fibres of the large root 

 simply to pass through, and, from unipolar cells, gives origin to 

 numerous moderately thick nerve-fibres, which join the branches 

 passing out of the ganglion. Bipolar cells also occur, but, as it 

 appears, in smaller numbers • and as for the apolar cells, the same 

 holds good as in the spinal ganglia. The terminal distribution 

 of the trigeminus is, for the most part, the same as that of the 

 cutaneous nerves in general, which is described in detail elsewhere. 

 The nervus Ungualis possesses 'peripheral ganglia. With regard to 

 the larger ganglia occurring on the trigeminus (ganglion ciliare, 

 oticum, spJieno-palatinum, lingitale, supra-maxillare), I find that 

 their structure is more like that of the sympathetic ganglia, only 

 they contain a considerable number of larger ganglion-globules. 

 The glosso-pharyngeus, although endowed with motor properties, 

 possesses, nevertheless, according to Volkmann, no fibres which do 



