1867.] 



On the Intimate Structure of the Brain, 



509 



May 23, 1867. 



Lieut. -General SABINE, President, in the Chair. 



The following communications v/ere read : — 



I. ^''Oii the Intimate Structure of the Brain.^'' — Second Series. 

 By J. LocKHART Clarke, Esq., F.R.S. Received May 1, 

 1867. 



(Abstract.) 



Abstracts of a considerable portion of this paper have been already 

 pubHshed in the Proceedings of the Eoyal Society for June 18, 1857, 

 and June 20, 1861, under the title of " Notes of Eesearches on the 

 Intimate Structure of the Brain." 



After adding several new facts, and giving further explanations on 

 the subject of the mechdla oblongata^ the author gives a full description 

 of the morphological changes by which the auditory and other centres 

 are developed out of elements of the spinal cord. The auditory centres 

 consist of an outer and an inner nucleus. The outer nucleus is deve- 

 loped from the grey substance of the posterior pyramid and restiform 

 body of the medulla. The inner nucleus arises betvv'een the posterior 

 pj-ramid and the nucleus of the eighth cerebral nerve. Erom both 

 these nuclei the posterior division of the auditory nerve takes its origin. 

 The anterior division consists of two portions. The principal portion 

 penetrates the medulla beneath the restiform body, and running along 

 the outer side of the caput cornu, or grey tubercle, enters both the 

 outer and inner nucleus. The other portion of the nerve runs back- 

 ward along the upper border of the restiform body, which it accompanies 

 over the superior peduncle of the cerebellum to the inferior vermiform 

 process. The outer auditory nucleus, consisting of the grey substance 

 of the posterior pyramid and restiform body, is ultimately thrown back- 

 ward into the cerebellum, part of it arching over the fourth ventricle to 

 the opposite side, w^hile the rest extends outward to the corpus deu- 

 tatum of the cerebellum. 



It would not be possible to give an abstract of the numerous details 

 of structure and the complicated connexions of different parts described 

 in the paper. The following facts, how^ever, may be mentioned. 



The roots of the facial nerve are shown to have a ver}^ remarkable 

 course and very complicated connexions with surrounding parts. On 

 reaching \X\q fasciculus teres they bend downward in the form of a loop, 

 the lower arm of which is connected with the motor nucleus of the 

 trigeminus and with the upper olivary body, as well as with their own 

 special nuclei. The longitudinal portion of this loop forms the column 

 which Stilling mistook for what he calls the " constant root of the trige- 

 minus," and which Schroeder van der Kolk mistook for one of the strinD 



