THE STRUCTURE OF THE MEDULLA OBLONGATA 



135 



pyramids and the central gray matter to form on either side of the median 

 plane a broad band of fibers known as the medial lemniscus (Figs. 96, 97). 



Fasciculus gracilis - 



Fasciculus cuneatus 



Dorsolateralfasc. (Lissauer) 



Substantial gelatinosa 



Dorsal column 



Lateral cortices pinal tract 



Central canal " 

 Ventral column 

 Ventral corticospinal tract " 



Funiculus gracilis 

 Nucleus gracilis 

 Funicnlus cuneatus 

 Spinal tract of trigem. nerve 

 Nucleus of spinal tract of 

 Dorsal column [N. V 



Lateral corticospinal tract 

 Central canal 



Decussation of the pyramids 

 Ventral column 



Fig. 94. 



Fig. 95. 



Funiculus gracilis 

 Nucleus gracilis 

 Funiculus cuneatus 

 Nucleus cuneatus 

 Spinal tract of trigeminal nerve 

 Nucleus of spinal tract of N. V 

 ^Central gray matter 

 Internal arcuate fibers 

 Central canal 

 Reticular substance 

 Medial lemniscus 

 Decussation of medial lemniscus 

 Decussation of the pyramids 

 Pyramid, corticospinal tract 



Fig. 96. 



- Fourth ventricle 

 ..-Dorsal motor nucleus of vagus 

 Nucleus of hypoglossal nerve 

 Tractus solitarius 

 Nucleus of spinal tract of N. V 

 ~t Spinal tract of trigeminal nerve 

 "Fibers of hypoglossal nerve 

 " Reticular substance 

 'Dorsal accessory olivary nucleus 

 "Medial lemniscus 

 'Inferior olivary nucleus 

 'Medial accessory olivary nucleus 



Pyramid, ccrticospinal tract 

 nganr 



Fig. 97. 



Figs. 9497. Diagrammatic cross-sections to show the relation of the structures in the 

 medulla oblongata to those in the spinal cord: Fig. 94, First cervical segment of spinal cord; 

 Fig. 95, medulla oblongata, level of decussation of pyramids; Fig. 96, medulla oblongata, level 

 of decussation of medial lemniscus; Fig. 97, medulla oblongata, level of olive. 



At the level of the middle of the olive most of the fibers of the funiculus cune- 

 atus and funiculus gracilis have terminated in their respective nuclei; and the 

 nuclei also disappear a short distance farther rostrally (Fig. 97). With the 



