WHITE MATTER OF MEDULLA. 



297 



opposite side; these form the middle links in many reflex arcs; 

 a few decussate in the posterior commissure and end in the thala- 

 mus. The latter are sensory conduction fibers. The descending 



Fig. 93. Section of the medulla oblongata at the middle of olive. (Original.) 



a. Nucleus of iath n. b. Vestibular nucleus, c. Tractus solitarius. d. Nucleus am- 

 biguus. e. Tractus spinalis n. trigemini. f. Medial accessory olivary nuclei, g. Posterior 

 lateral sulcus. h. Ant. external arcuate fibers, i. Fasciculus proprius. j. Arcuate nucleus. 

 k. Anterior longitudinal bundle in substantia reticularis alba. 1. Medial longitudinal bundle. 

 m. Nucleus alae cinerea. n. Taenia of 4th ventricle, o. Restiform body. p. Gelatinous 

 substance, q. Substantia reticularis grisea nucleus lateralis inferior, r. Ascending ant. 

 cerebello-spinaj, spino-thalamic, and rubro-spinal tracts, s. Dorsal accessory olivary nu- 

 cleus, t. Inferior olivary nucleus, u* Pyramid, v. Medial fillet, interolivary stratum. 



part of the medial longitudinal bundle is the medial ponto-spinal 

 tract of Collier (see pages 280, 360 and 373). 



The anterior longitudinal bundle (Figs. 92 and 95) descends 

 as a distinct strand, from the opposite superior colliculus of the 



