MEDULLA OBLONGATA 



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bellar peduncles (crura cerebelli ad medullam oblongatam) and contain the major- 

 ity of tlie ascending fibres, which associate the cerebellum with the structures 

 below it. 



In toto, the restiform bodies are much larger than could be formed by the combined cere- 

 bellar fascicuU of the spinal cord, their great size being due to their receiving numerous axones 

 coursing in both directions, which connect the cerebellum with structures contained in the 

 medulla oblongata alone, so that in the medulla they increase as they approach the cerebellum. 

 Their mesial borders form the lateral boundaries of the fourth ventricle. Their name {restiform, 

 meaning rope-Uke) was suggested from the appearance frequently given them by the fibres 

 of the cochlear (acoustic division of the eighth) nerve, which course around their lateral per- 

 iphery to become the strioe medullares in the floor of the fourth ventricle. 



Fig. 630. — Diagram Showing the Decussation of the Pyramids. 

 The uppermost level represented is near the inferior border of the pons. 



Chorioid tela of fourth ventricle 

 Solitary tract 



Nucleus of vestibular nerve 



Restiform body 

 .. Spinal tract of trigeminus 

 -—Nucleus of cochlear nerve 



-/ Vagus nerve 



- Hypoglossal nerve 

 Pyramid 



Spinal tract of trigeminus 



Decussation of pyramids 



Lateral cerebro -spinal fasciculus 

 (crossed pyramidal tract) 



Ventral cerebro-spinal fasciculus 

 (direct pyramidal tract) 



Upon removal of the cerebellum it may be seen that below the calamus scrip- 

 torius (inferior terminus of the fourth ventricle) the structures manifest in the dor- 

 sal surface of the medulla are directly continuous with those of the spinal cord. 

 The fasciculus gracilis (Goll's column) of the spinal cord acquires a greater height 

 and volume and becomes the funiculus gracilis of the medulla, and because of this 

 increased height the posterior median sulcus of the cord becomes deepened into the 

 posterior median fissure. The posterior intermediate sulcus is also accentuated 

 by the fasciculus cuneatus (Burdach's column) likewise now enlarged into the 

 funiculus cuneatus of the medulla. The lateral funiculus of the medulla, of 

 course, does not contain the lateral or crossed pyramidal tract present in the spi- 

 nal cord. 



At the border of the calamus scriptorius the funiculus gracilis terminates in a 

 slight elevation, the clava, which is the superficial indication of the nucleus of the 

 fasciculus gracilis. Beginning somewhat more anteriorly, and having a somewhat 

 greater length, is a similar enlargement of the funiculus cuneatus, the tuberculum 

 cuneatum or nucleus of the fasciculus cuneatus. 



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