776 



NEUROLOGY 





The fasciculus gracilis and fasciculus cuneatus constitute the posterior sensory 

 fasciculi of the medulla spinalis; they are prolonged upward into the lower part 



FIG. 687. Section of the medulla oblongata through 

 the lower part of the decussation of the pyramids. (Tes- 

 tut.) 1. Anterior median fissure. 2. Posterior median 

 sulcus. 3. Anterior column (in red), with 3', anterior 

 root. 4. Posterior column (in blue), with 4', posterior 

 roots. 5. Lateral cerebrospinal fasciculus. 6. Posterior 

 funiculus. The red arrow, o, a', indicates the course the 

 lateral cerebrospinal fasciculus takes at the level of the 

 decussation of the pyramids; the blue arrow, 6, V, indi- 

 cates the course which the sensory fibers take. 



Fio. OSS. Section of the medulla oblongata at the 

 level of the decussation of the pyramids. (Testut.) 1 

 Anterior median fissure. 2. Posterior median sulcus. 

 3. Motor roots. 4. Sensory roots. 5. Base of the 

 anterior column, from which the head (5') has been 

 detached by the lateral cerebrospinal fasciculus. 6. 

 Decussation of the lateral cerebrospinal fasciculus. 7. 

 Posterior columns (in blue). 8. Gracile nucleus. 



N. VI 

 Nn. VII, VIII 



'Decussation 



FIG. 689. Superficial dissection of brain-stem. Ventral view. 



of the medulla oblongata, where they end respectively in the nucleus gracilis and 

 nucleus cuneatus. These two nuclei are continuous Avith the central gray substance 



