12 GRAY SUBSTANCE OP THE MEDULLA OBLONGATA. 



medulla were arranged with respect to the central canal much as in the spinal 

 cord, are now spread out upon a very long base forming the extended floor of the 

 fourth ventricle. 



The upward extension of the hypoglossal nucleus still contains numerous small 

 cells, from which is subsequently developed the fasciculus teres, forming the nucleus 

 of the abducens and facial nerves. The restiform body no longer presents the same 

 appearance as in lower sections, but consists interiorly of a large group of cells (r, r) 

 the remains of the restiform nucleus, from which as a common centre, a mass of 

 fibres radiate in an obliquely ascending course, becoming more and more horizontal 

 as we approach the cerebellum, which the restiform body, as is well known, finally 

 enters. 



Winding around the outer border of the restiform body is seen the posterior 

 division of the auditory nerve ( VIIF), containing, as noticed by Stilling, numerous 

 little cells (z) near its entrance into the medulla. The caput is still prominent and 

 contains numerous cells, connected by a small group with the large nucleated mass 

 from which the glosso-pharyngeal and auditory roots arise. The whole antero-lateral 

 and anterior substance of the medulla in this region, contains numerous cell groups, 

 some of considerable size, and small ceU groups are very often found scattered 

 among the decussating fibres of the raphe. The olivary columns have here reached 

 their greatest development, and begin immediately to diminish in size, as is also 

 the case with the anterior pyramidal columns, giving place to the extremely compli- 

 cated plexus of fibres constituting the pons Varolii, many of which are intimately 

 connected with and to some extent developed from the little cell groups so constantly 

 found at different points in the substance of the pyramids (Fig. 24'", i). 



