198 



THE ESSENTIALS OF HISTOLOGY 



FIG. 232. OBLIQUE SECTION 

 OF THE PONS ALONG THE 

 LINE OF EXIT TRAVERSED 



BY THE FIFTH NERVE. f 



The section passes through the 

 lower part of the motor nu- 

 cleus (n'v) from which a bundle 

 of fibres of the motor root is 

 seen passing, V ; a part of the 

 upper sensory nucleus (r) is 

 also shown in the section in the 

 form of a number of small iso- 

 lated portions of grey matter. 

 Amongst these are a few 

 bundles of the ascending root 

 cut across, but most of these 

 have already become diverted 

 outwards to join and assist in 

 forming the issuing part of the 

 main or sensory root, V; I, 

 small longitudinal bundle of 

 fibres near the median sul- 

 cus (m.s. ), passing outwards 

 to join the root of the fifth 

 nerve ; f.r. formatio reticu- 

 litris ; /, raphe ; s.f. substau- 

 tia ferruginea. 



FIG. 233. TRANSVERSE SECTION THROUGH THE UPPER PART OF THE PONS. 



more than twice the natural size.) 1 



p, transverse fibres of the pons ; py, jiy, bundles of the pyramids ; a, boundary line between 

 the tegmeutal part of the pons "and its ventral part ; V, oblique fibres of the fillet, passing 

 towards 1,1', longitudinal fibres of the fillet; f.r. formatio reticularis : p.l. posterior 

 longitudinal bundle ; s.c.p. superior cerebellar peduncle : c.m. superior medullary velum ; 

 6, erey matter of the lingula : r. 4, fourth ventricle ; in the grey matter -which bounds it 

 laterally are seen, d.V. the descending root of the fifth nerve, with its nucleus, s.f. sub- 

 stantia ferruginea, g.c. group of cells continuous with the nucleus of the aqueduct. 



I The details of this and of several of the preceding figures are filled in under a somewhat 

 higher magnifying power than that used for tracing the outlines. 



