MR. J. L. CLARKE OF THE INTIMATE STRUCTURE OF THE BRAIN. 301 
although the principal, is not the only, nucleus of the facial nerve ; for some of the 
superficial or posterior fibres, as represented in fig. 56, may be traced backward and 
inward to the superficial grey layer (</", g") of the fasciculus teres , and especially to a 
group of cells (g'") situated on its outer side. Behind this group are the cut-ends of 
three considerable blood-vessels enveloped in their sheaths. The trunk of the nerve (q") 
is frequently separated into two portions by a long and broad streak of grey substance 
(q'") containing some nuclei or small cells and the branches of a blood-vessel, and behind 
these the fibres are again separated by long and narrow streaks of longitudinal fibres., 
represented by the dotted tracts. 
(55) In transverse sections of the medulla made along the uppermost border of the 
facial nerve, almost all traces of the principal nucleus disappear, and almost all the fibres 
of the nerve may be seen to enter the longitudinal portion of the loop (T", fig. 56, 
Plate XIII.). Of those that run inward along the front of this portion of the loop, 
some turn backward to enter it (at V'), while others pass onward to decussate across the 
raphe (at h), the rest appearing to stop at its inner side ( h fig. 52), at the edge of the 
median furrow, where they seem to become longitudinal, amongst the cut-ends of a 
layer of longitudinal fibres. The fibres of the nerve which pass round the posterior 
surface (T", fig. 56), all enter it in succession, none of them reaching the raphe, or even 
so far as the inner side of T", but terminating in it about the point l " ; so that it is not 
even enclosed by fibres of the nerve. 
Some of these uppermost fibres of the facial nerve, however, instead of running down 
with the longitudinal portion of the loop, diverge somewhat upward and backward 
amongst an irregular group of smaller cells and nuclei (as represented at v", fig. 55) 
lying beneath the surface of the fourth ventricle. 
(56) Such is the remarkable and complicated course of the roots of this importamt 
nerve. The accounts which Stilling and Schroder van der Kolk have given of the 
origin of the facial are very imperfect, and contain serious errors. Stilling, however, 
has the merit of discovering that the lower fibres of the nerve arise from the large nucleus 
of multipolar cells. Higher up the fibres appeared to him to run inward to the raphe, 
without entering the nucleus, and to decussate with their fellows of the opposide side. 
In this course they enclose in front and behind, but do not enter the longitudinal column, 
which I have shown to be the longitudinal portion of the loop of the facial nerve itself. 
This column is considered by him to be what he calls “ the constant root of the trige- 
minus” or fifth cerebral nerve. At the upper limit of the nerve he found that all traces 
of the nucleus had disappeared ; but he thought that the fibres bend downward to the 
nucleus below, while the rest run through the raphe to the columns which he considers 
as prolongations of the anterior columns of the spinal cord. Upon these points, however, 
he speaks with some diffidence*. 
(57) Schroder van der Kolk’s account is exceedingly defective, being scarcely more 
than “ a general assent to the description of the course of the facial nerve given by 
* Stilling, Pons Varolii, pp. 37, 38, plates 3, 4 & 5. 
