286 ME. J. L. CLAEKE ON THE INTIMATE STEUCTUEE OF THE BEAIN. 
longitudinal bundles. How many of these fibres belong to those portions of the lateral 
columns of the cord that have not contributed to the formation of the pyramids, it is 
not easy to determine ; but it is certain that the greater number of them are new and 
finer fibres, arising from the grey substance of the medulla. Nearer the surface, 
however, and more anteriorly, the original and coarser fibres of the antero-lateral 
columns of the cord continue to ascend the medulla ( d , figs. 4, 5, 6, 8, Plate VIII., and fig. 
27, Plate X.). Schroder van der Kolk believed that some of the original fibres of the 
lateral columns of the cord ascend on the same side beyond the decussation, but that 
they terminate, at the vagal nucleus, in the slender longitudinal column n, figs. 25 & 27, 
Plate X.* This opinion, as will be readily seen, must be erroneous ; for it is very uncer- 
tain whether the slender column (n) contains any of the original fibres of the lateral 
columns; and even if it does, it is merely an offset from the layer d! (fig. 27, Plate X.), 
which continues to ascend much beyond its point of divergence ( n '), and, as I have 
shown, consists, chiefly, at least, of new and finer fibres ; while at the same time the 
superficial and original fibres of the lateral columns ( d , fig. 27, Plate X.), like the layer 
d', continue their course upward much beyond the point of divergence (n 1 ) of the slender 
longitudinal column. 
(30) I have already shown that the lit.tle group of small cells (T, fig. 38, Plate XI.) 
which lies on the inner side of the hypoglossal nucleus (J), increases as it ascends the 
medulla. In fig. 39, Plate XI., just where the hypoglossal nucleus ends, it is much 
larger, is nearer the surface, and together with the outer column K', constitutes the 
“ fasciculus teres” or longitudinal column which runs along the fourth ventricle on each 
side of the median line. Near the level of the auditory nerves this small and inner 
group (T) sometimes lies with its long axis more vertical, as in fig. 40, Plate XI., and 
therefore forms a slightly prominent column which borders the side of the median 
sulcus, while the outer column (K') is more divergent, and runs along the inner side of 
the auditory nucleus (i), to reach the digital fossa of the ventricle. It will be seen that 
in fig. 40 this outer portion (K') of the “ fasciculus teres” as a separate column, has 
diminished in size, while it has become intimately blended with the auditory nucleus ( [i ), 
from which, in fig. 38, it was completely separated by the interposition of the vagal 
nucleus ( t , PI). Amongst the commissural fibres (?/) which decussate across the raphe, 
there is a conspicuous group of large multipolar cells. 
(31) Of the Striae Medullares . — In the floor of the fourth ventricle of the human 
medulla, a variable number of white bundles, of different sizes, and composed of nerve- 
fibres, are seen running in several directions, but chiefly more or less transversely, from 
the median sulcus, over the “fasciculus teres ” and the auditory nucleus toward the root 
of the auditory nerves. These bundles are known to anatomists by the name of striae 
medullares , and have been made the subject of investigation by Piccolomini, Soem- 
mering, Santorini, Prochaska, Rudolphi, the Wenzels, Gall, Spurzheim, Cuvier, 
Treviranus, Boek, Langenbeck, Arnold, Serres, Burdach, Bergmann, Heusinger and 
* Schroder tan der Kolk, Medulla Oblongata. 
