406 ANATOMY OF THE CENTEAL NERVOUS SYSTEM. 



side opposite to the origin of the pyramids in the cortex, by means of col- 

 laterals. Prom the cells in the anterior horns arise the motor roots. 



3. The central path for the motor cranial nerves is better known for 

 the facial and hypoglossal. 



The facial tract arises in the region of the lower third of the central 

 convolutions, probably only for its lower branches, the source of the frontal 

 part of it being unknown (gyrus angiilaris?); extends from there inward 

 transversely over the nucleus lentiformis, and arrives very close to the py- 

 ramidal tract in the internal capsule. At any rate, in the pes cerebri it is 

 clinically not distinguishable from the pyramid. Its fibers then leave the 

 general motor tracts probably with the familiarly called "bundle from the 

 crusta to the tegmentum." Certain it is, that in the pons it is separated 

 from the other motor paths (see Fig. 258). How it reaches the nucleiis is 

 as yet unknown. But it finally arrives at the crossed facial nucleus in the 

 inferior portion of the pons. From this arises the nerve. 



In the most ventral part of the anterior central convolution probablj'' 

 lies the cortical area for the hypoglossus. From this region, at least, there 

 passes downward a bundle, Centrally to the facial fasciculus, whose interrup- 

 tion has caused at times bilateral hypoglossal distxirbances. As it extends 

 from the cortex to the capsula interna it passes over the upper edge of the 

 nucleus lentiformis, and must'lie in close proximity to the speech-fibers just 

 external to the beginning of the tail of the caudate nucleus. In a case 

 observed by the writer, a focal lesion of about the size and thickness of a 

 dime interrupted both tracts at this place. In the capsule the hypoglossal 

 fibers probably run between those of the facial and those for the extremities. 

 Within the pons its fibers must be separated from the pyramid, and probably 

 pass in the above-named bundle median to the fillet, posteriorly and u.pward 

 in the raphe. It joins the opposite nucleus (and that of the same side?) after 

 reaching the oblongata, and from the nucleus arises the nerve. 



4. The motor speech-tract. Of this we know certainly but few facts: 

 the starting-point in the lower frontal convohTtion, the termination in the 

 nuclei of the facial and hypoglossal, and an intermediate point, lying exter- 

 nal to the tail of the caudate nucleus. Probably (Wernicke) this tract ex- 

 tends from Broca's convolution — the inferior frontal — somewhat internally 

 and in a nearly horizontal direction dorsal to the capsula externa, under 

 cover of the insula. Its fibers then arrive in the portion of the internal 

 capsule posterior to the general motor paths and then in the pes cerebri. In 

 the pons they must rise gradually out of the crusta and into the tegmentum. 

 In all of these places mentioned disease produces disorders of speech. 



Every motor nerve then arises in a nucleus in the central organ. The nerve 

 and its nucleus form the first division of the path; to the nucleus there extends 



