1354 



A MANUAL OF ANATOMY 



matter on the dorsal and lateral aspects of the central canal, and 

 it may be regarded as being, in large part, an extension from the 

 basal part of the dorsal grey cornu. It is elongated and increases 

 in size as it ascends. It gives rise to the prominence of the funi- 

 culus gracilis and to the clava, and the fibres of the funiculus 

 gracilis, as they ascend, terminate at intervals around the cells of 

 the nucleus. 



The nucleus cuneatus is a collection of grey matter within the 

 funiculus cuneatus. It is a direct extension from the basal part of 

 the dorsal grey cornu which lies on the dorsal and lateral aspects 

 of the central canal. Like the nucleus gracilis it is elongated, and 

 increases in size as it ascends. It gives rise to the prominence of 



Fig. 567. — Section of the Medulla Oblongata through the Lower 

 Part of the Decussation of the Pyramids (L. Testut's 'Anatomie 



HUMAINE '). 



1. Anterior Median Fissure 



2. Posterior Median Fissure 



3. Anterior Cornu 



3; Anterior Nerve-roots 



4. Posterior Cornu 



4I Posterior Nerve-roots 



5. Crossed Pyramidal Tract 



6. Column of Burdach 



The red arrows, a, a', indicate the paths taken by the crossed Pyramidal Tracts 

 at the level of the decussation of the Pyramids ; and the blue arrows, 

 b, b', indicate the paths of the Sensory Fibres. 



the funiculus cuneatus and to the cuneate tubercle, and the fibres 

 of the funiculus cuneatus, as they ascend, terminate at intervals 

 around the cells of the nucleus. 



On the outer side of the nucleus cuneatus there is a small collection of 

 grey matter, which is known as the external or accessory cuneate nucleus. It 

 is on a higher level than the decussation of the pyramids, and it may be 

 regarded as a detached portion of the substantia gelatinosa of Rolando. 



The olivary nuclei are associated with the olive, and are three in 

 number — namely, inferior, and two accessory — mesial and dorsal. 



The inferior olivary nucleus, which is the chief nucleus, is situated 

 within the olive. As seen in transverse sections through the olive, 

 it appears as a wavy lamina of grey matter, curved in such a manner 

 as to form an incomplete capsule, which encloses white matter. 

 The open part of the capsule is called the hilum, and is directed 



