SEGMENTS OF TRIGEMINAL NERVE-GROUP 265 
and of facts derived from post-mortem dissections, that one may 
venture to designate the portion of the nucleus from which the 
innervation of each individual ocular muscle comes. He gives Starr’s 
table, the latest of these numerous attempts, begun by Pick. Accord- 
ing to Starr, the nuclei of the nerves to the individual muscles are 
arranged from before backward, thus— 
m. sphincter tridis. m. ciliaris. 
m. levator palpebree. m. rectus internus. 
m. rectus superior. m. rectus inferior. 
m. obliquus inferior. 
Further, the evidence of the well-known physiological experi- 
ments of Hensen and Volckers that the terminal branches of the 
oculomotor nerve arise from a series of segments of the nucleus, 
arranged more or less one behind the other in a longitudinal row, 
leads them to the conclusion that the nuclei of origin are arranged as 
follows, proceeding from head to tail :— 
Nearest brain. . ciliaris. 
. sphincter tridis. 
. rectus internus. 
. rectus superior. 
. levator palpebree. 
. rectus inferior. 
Most posterior. . m. obliquus inferior. 
It is instructive to compare this arrangement of Hensen and 
Vélckers with the arrangement of the origin of these muscles from 
the premandibular cavity as given by Miss Platt. 
Thus she states that the most posterior part of the premandibular 
cavity is cut off so as to form a separate cavity, resembling, except 
in position, the anterior cavity; this separate, most posterior part 
gives origin to the inferior oblique muscle. She then goes on to 
describe how the dorsal wall of the remainder of the premandibular 
cavity becomes thickened, to form posteriorly the rudiment of the 
inferior rectus and anteriorly the rudiments of the superior and 
internal recti, a slight depression in the wall of the cavity separating 
these rudiments. The internal rectus is the more median of the 
two anterior muscles. In other words, her evidence points not only 
to a fusion of somites to form the premandibular cavity, but also 
to the arrangement of these somites as follows, from head to tail: 
(1) internal rectus, (2) superior rectus, (3) inferior rectus, (4) inferior 
“ImorP © woe 
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