66 
THOMPSON YATES LABORATORIES REPORT 
In Macacus rhesus and sinicus, therefore, the so-called 1st cervical nerve, the sub-occipital, 
possesses no dorsal (afferent) root, and, as a consequence, no sensory skin-field ; my observations, 
however, liave not been numerous enougli to do more than determine what is the general rule ; 
it is possible that occasionally the 1st cervical possesses a posterior root, whether that then has a 
skin-field must remain an open question ; its distribution may be confined to muscles, ligaments, etc. 
As is well known, tlie 1st cervical nerve in Man does occasionally possess a small dorsal (afferent) 
root, on which is the usual spinal ganglion. In the Chimpanzee this dorsal root and ganglion is 
usually present, but not in the Orang, nor in the Cynomorphic Apes.* In the Dog and Cat the 
ganglion and root are, as far as I have seen, always present ; also in the Rabbit and Guinea-pig. 
In the Cat the field of this root includes the apex of the pinna. 
Motor Distribution, 
This has been examined in four individuals, partly by mechanical excitation of the motor 
root, partly by farad ic excitation of the primary, ventral, and dorsal divisions as near their origin as 
possible. The following are the results obtained : a certain amount of individual variation occurs, 
especially with regard to superior obliquvis muscle. 
Dorsal Primary Division. — Rectus posticus major, rectus posticus minor, obliquus inferior, 
obliquus superior, trapezius. 
Ventral Primary Division. — Sterno-mastoideus, sterno-hyoideus, sterno-thyroideus, omo- 
hyoideus (especially anterior belly,) rectus lateralis, rectus anticus minor, genio-hyoideus and 
thyro-hyoideus. 
IInd Cervical Nerve (Figs. 4, 5, and 6) 
The anterior boundary of the skin-field of this nerve has been delimited in six individuals ; 
the posterior in five individuals. 
Anterior Border. (Fig. 6.) 
Example. — M. rhesus. Large female, not very young. At 1 1 a.m., the left Vth cranial 
nerve cut in the middle cranial fossa proximal to the Gasserian ganglion. At 9.30 p.m. 'the 
anterior boundary of the field of response starts from the mid-dorsal line of the scalp at a point 3 
centims. behind the supra-orbital ridge. The boundary runs thence in an almost rectilinear course 
transversely outwards to a point somewhat above and considerably in front of the top of the root 
of the pinna. From that point it begins to slope forwards, passing about midway between the 
outer edge of the orbit and the root of the pinna. In front of the tragus it lies 23 millims. distant 
from that. It cuts a line drawn from the root of the pinna to the angle of the mouth just about 
midway between those two points, and then sloping more abruptly forward, it passes about 15 
millims. behind the angle of the mouth. It winds round the lower edge of the horizontal ramus 
of the jaw and reaches the mid-ventral line of the neck at a point a little in front of a vertical 
dropped from the angle of the mouth.' 
* A. Froriep anil W. Beck, loc. cit. 
