EFFERENT, OR MOTOR PATHS. 369 



missure. Impulses by either route finally reach the anterior gray 

 columna of the spinal cord and, with the exception of a small 

 per cent, of them, they reach the columna opposite to their cortical 

 origin. The few undecussated fibers in the lateral pyramidal 

 tract conduct uncrossed impulses to the anterior columna of the 

 same side. Thus are explained two symptoms of hemiplegia 

 due to cerebral lesion, viz., weakness on the well side and slight 

 motion on the paralyzed side. From the anterior gray columna 

 of the spinal cord the nerve commotions are conducted by the 

 efferent, or motor fibers of the spinal nerves to the muscles. 



2. Through the Cerebral Nerves (Fig. 105). Impulses des- 

 tined to the cerebral nerves run chiefly from the lower two-fourths 

 of the anterior central gyrus through corona radiata, genu of in- 

 ternal capsule and on, by the same path as the impulses to spinal 

 nerves, down to the point where they leave the pyramidal tract 

 to enter the nuclei of the cerebral nerves, which some of them do 

 in the vicinity of the several nuclei. According to Bechterew 

 they run, at least in part, through pyramidal fibers which consti- 

 tute the accessory lemniscus. These fibers leave the pyramidal 

 tract near the internal capsule, and descend through the medial 

 portion of the fillet to points near the respective nuclei in which 

 they end by multiple division. From either hemisphere impul- 

 ses proceed to the nuclei of both sides. But the greater number 

 enter the nucleus of the fourth nerve on the same side, and the 

 nuclei of the third, fifth, sixth, seventh, ninth, tenth, eleventh 

 and twelfth cerebral nerves of the opposite side. By the above 

 nine nerves innervation is conducted to the muscles of the 

 orbit; the muscles of mastication, and expression; the muscles 

 of the tongue, palate and ear; the digastric and styloid muscles; 

 the muscles of the larynx, trachea and bronchi, and of the pharynx, 

 esophagus, stomach, and the intestines down to the descending 

 colon. And inhibitory impulses are carried to the heart; also 

 vasodilator, secretory, trophic and inhibito-secretory impulses 

 to alimentary glands, etc. 



THE CEREBRO-PONTAL PATHS, FRONTAL, TEMPO- 

 RAL AND INTERMEDIATE. These paths are indirect, for 



spinal nerves, since they run through the cerebellum. 

 24 



