EXAMINATION OF SOME SPINAL NERVES 
67 
* The crossed overlap of the Vth cranial on the face and tongue is very slight indeed, but 
the crossed overlap of the Ilnd cervical, both on scalp and under chin, is considerable.' 
Posterior Border. 
Example. — M. rhesus. Female, not young. At 9. 30 a.m. the dorsal (sensory) roots of the 
Ilird, IVth, Vth, Vllth, and Vlllth cervical and of 1st and Ilnd thoracic nerves of the right side 
severed in the vertebral canal. At 4.45 the final delimitation of the border of the upper field of 
response (Ilnd cervical) completed. ' The boundary starts from the mid-dorsal line of the neck 
at a point 1.5 centims. below the external occipital protuberance, and at a level about i centim. 
below the level of the lowest point of the root of the pinna. It slopes outwards and passes 2 
centims. below the root of the pinna. It runs just below and behind the angle of the lower jaw. 
It meets the ventral crossed overlap of the opposite side a few millims. below the lower edge of 
the cricoid cartilage.' 
Fig. 6. 
Anterior border of Ilnd cervical. Lines obtained on April 19, 1893, and April 13, 1893, compared. 
Variation. 
In one adult female the Ilnd cervical skin-field reached in its ventral part further forward 
than in the other observations. The anterior border in the exceptional instance approached to 
within 7 millims. of the angle of the mouth, and sloping nearly horizontally along the lower edge 
of the jaw, turned under it and finally met the mid-ventral line only some 3 millims. behind the 
symphysis of the lower jaw. In Monkeys there is no mental eminence, but the position of the 
line is such as to suggest that in Man the skin-field of the Ilnd cervical will sometimes include 
the point of the chin, but will usually fall just short of that. 
