444 THE BRAIN OF MAMMALS, BY TH. MEYNERT. 



inferiorly indistinguishable from the similar cells of the emi- 

 nentia teres. 



The nucleus common to the oculomotorius and trochlearis 

 nerves is in connection (1) with straight fibres of the raphe 

 (fig. 249, in, P'\ which, in so far as they are not already con- 

 nected with precisely similar cells distributed through the 

 raphe itself, spread out with their innermost fasciculi in the 

 scattered masses of the above-named nucleus, and penetrate 

 with their middle and external fasciculi into its compact 

 portion. They thus form finely fasciculated curves, convex 

 internally, to which the internal and somewhat smaller nerve 

 corpuscles of the nucleus are completely parallel. Between 

 this peripheric termination of these fibrse rectse and their 

 centric origin is an acute-angled decussation. These fibres 

 arise from the lenticular nucleus as the innermost fasciculus 

 of the crusta belonging to the deep stratum of the ansa 

 peduncularis. They constitute for the common nucleus of 

 the third and fourth nerves that which the decussating 

 fasciculi of the pyramids are for the nuclei of origin of the 

 anterior roots of the spinal cord. They are therefore the 

 shortest fasciculi of the system of the crus cerebri, because, 

 having arisen from the lenticular nucleus, they at once pene- 

 trate into the most elevated of the motor-nerve nuclei, and 

 here peripherically terminate in the grey matter of the central 

 cavities. 



2. From the nuclear mass common to the third and fourth 

 nerves in which these fasciculi terminate, the roots of the 

 third or oculomotorius nerve arise (fig. 249, III') in the form 

 of large bundles that run forwards through the tegmentum on 

 the inner side of the crusta, curving outwards as if they were 

 a continuation of the course of the fibrse rectse; they partly 

 traverse the red nucleus of the tegmentum, and in part are 

 situated to its inner side. If it be borne in mind that certain 

 fasciculi of the corona radiata terminating in the lenticular 

 nucleus, represent the upper link of a projection tract, of which 

 the second link, arising from this nucleus and running its 

 course in the crusta, passes as decussating fibrae rectge of the 

 raphe into the nucleus of the oculomotorius, and the third 

 link of which is found in the third nerve, this easily com- 



