ISTHMUS OF THE ENCEPHALON 



lateral funiculus of the cord. As the fibers pass upward, however, they 

 diverge in several directions. The fibers of the crossed pyramidal tract 

 cross the median line, as previously stated, to enter into the formation of 

 the ventral funiculus; the fibers of the dorsal spino-cerebellar tract 



15, 



30 



FIG. 232. ANTERIOR OR VENTRAL 

 VIEW OF THE MEDULLA OBLONGATA 

 AND ISTHMUS. i. Infundibulum. 2. 

 Tuber cinereum. 3. Corpora albicantia. 

 4. Cerebral peduncle. 5. Tuber an- 

 nulare. 6. Origin of the middle pe- 

 duncle of the cerebellum. 7. Anterior 

 pyramids of trie medulla oblongata. 



8. Decussation of the anterior pyramids. 



9. Olivary bodies. 10. Restiform bodies, 

 n. Arciform fibers. 12. Upper ex- 

 tremity of the spinal cord. 13. Liga- 

 mentum denticulatum. 14, 14. Dura 

 mater of the cord. 15. Optic tracts. 

 1 6. Chiasm of the optic nerves. 17. 

 Motor oculi communis. 18. Patheticus. 

 19. Fifth nerve. 20. 20. Motor oculi 

 externus. 21. Facial nerve. 22. Au- 

 ditory nerve. 23. Nerve of Wrisberg. 

 24. Glosso-pharyngeal nerve. 25. 

 Pneumogastric. 26, 26. Spinal ac- 

 cessory. 27. Sublingual nerve. 28, 29, 

 30. Cervical nerves. (Sappey.) 



FIG. 233. POSTERIOR OR DORSAL 

 VIEW OF THE MEDULLA OBLONGATA, 

 ISTHMUS, AND BASAL GANGLIA, i. Corpora 

 quadrigemina. 2. Corpus quadrigeminum 

 anterius (pregeminum). 3. Corpus quad- 

 rigeminum posterius (post-geminum) . 4. 

 Tract of fibers (brachium) passing to the 

 corpus geniculatum externum. 5. Tract of 

 fibers (brachium) passing to 6, the corpus 

 geniculatum internum. 7. Posterior com- 

 missure. 8. Pineal gland. 9. Superior 

 cerebellar peduncle. 10,11,12. The valve 

 ofVieussens. 13. The pathetic nerve. 14. 

 Lateral groove of the isthmus. 15. 

 Triangular bundle of the isthmus. 16. 

 Superior cerebellar peduncle. 17. Middle 

 cerebellar peduncle. 18. Inferior cerebellar 

 peduncle. 19. Anteroinferior wall of the 

 fourth ventricle. 20. Acoustic nerve. 21. 

 Spinal cord. 22. The posteromedian 

 column. 23. The posterior pyramids. 

 (Sappey.} 



gradually curve backward, and in so doing unite with other fibers to 

 form the restiform body, after which they enter the cerebellum by way of 

 the inferior peduncle. Situated between the ventral pyramid and the 

 restiform body is a small oval mass, the olivary body, composed of both 

 white and gray matter. 



