498 THE BRAIN OF MAMMALS, BY TH. MEYNERT. 



internal auditory nucleus is consequently only a smaller similar 

 triangle, incompletely separated by the fasciculi of the internal 

 division of the crus cerebelli from the general triangle which 

 the confluent area of transverse section of the external nucleus 

 forms with it. In its internal half this external nucleus is 

 traversed by the internal division of the cerebellar peduncle, 

 the areas of which are seen in transverse section ; but the 

 outer part is of a pure grey (fig. 255), and includes very 

 numerous multicaudate slender nerve corpuscles, having a 

 length of from 60 100 ju, and a thickness of 15 21 ^u. 



3. The anterior auditory nucleus (fig. 255, 8 2 ) is a wedge- 

 shaped mass intercalated between the auditory nerve, the 

 corpus restiforme, and the medulla of the flocculus, forming a 

 triangular area three millimeters in height and two millimeters 

 broad. It includes a large number of closely arranged vesi- 

 cular nerve corpuscles with but few processes, that vary from 

 15 21 JJL in size, and which, whilst differing from those of the 

 interspinal ganglia in their small size, resemble them in their 

 form and in their being enclosed in a sheath beset with delicate 

 small nuclei. 



4. The nerve corpuscles of the auditory root. These are dis- 

 tributed either singly or in small clusters throughout its entire 

 central course, but by their accumulation swell it out into the 

 form of a ganglion at the point of its emergence at the anterior 

 border of the pons, and are deposited to an equal extent in the 

 external portion of the root which embraces the crus cerebelli. 

 Their for the most part large size, their elongated and multi- 

 caudate form, and the absence of a capsule in them, prevent us 

 from agreeing with Stilling and Clarke in considering that 



8 2 from Stilling's anterior auditory nucleus, in 8 3 from the internal 

 division of the cerebellar peduncle, and in 8 4 from the external divi- 

 sion of the same ; D, the dentated nucleus in the cerebellum ; T, the 

 nucleus of the roof (Stilling) in the cerebellum ; jB, the medullary 

 mass of the superior peduncle (processus e cerebello ad testes) in the 

 cerebellum ; jET 1 , fasciculi of the internal division of the cerebellar 

 peduncle undergoing, and H 2 similar fasciculi apparently not under- 

 going, decussation ; F, the peduncle of the flocculus on the right side, 

 likewise as transverse sectional area and as oblique longitudinal fas- 

 ciculi above the corpus restiforme. 



