EXAMINATION OF SOME SPINAL NERVES 
69 
Posterior Border. 
Example. — M. rJmus, 9. At 11. 20 a.m. the posterior roots of the IVth, Vtli, Vltli, 
Vllth, Vlllth cervical and 1st and Ilnd thoracic nerves divided inside the vertebral canal. At 
5.15 p.m. the lower border of the IlIrd cervical finally delimited. 
' The upper field of response has the following boundary : from the mid-dorsal line 
decidedly below the level of a line joining the lowest points of the roots of the two pinnae, 
and thence outwards and slightly downwards for a distance of 2 centims. The line then turns 
more steeply downward well behind the posterior edge of the acromial end of the clavicle to strike 
the spine of the scapula just at the root of the acromion. It then turns forward over the outer 
end of the clavicle and again retires, thus making an angular notch, and reaching the top of the 
great tuberosity of the humerus. Finally it passes fairly horizontally inward well below the 
clavicle on the pectoral muscle, and reaches the ventral crosslap just above the junction of tlie 
2nd costal cartilage with the sternum.' 
Fa nation. 
The level of the posterior border at the mid-dorsal line is sometimes distinctly below 
the point found in the above experiment, but once it was on a level exactly with the line between 
the lowest points of the roots of the pinnae. On two occasions, instead of running well below 
the clavicle, the line just followed the lower border of the clavicle. On one occasion the ventral 
end of the line passed between the ist and 2nd cartilages somewhat nearer the second. The 
little notch in the border, close to the acromio-clavicular joint, was a constant feature of the 
field in all the experiments. 
Muscular Distribution. 
Examined in four individuals. 
Dorsal primary division : — Complexus, splenius, trachelo-mastoideus, trapezius, cervicalis 
ascendens, transversi spinales. 
Ventral primarv division : — Longus colli, rectus anticus major, levator anguli scapulas ; 
omo-hyoideus, post, belly ; sterno-hyoideus, lower part. 
IVth Cervical Nerve (Figs. 4 and 5) 
The anterior border of this skin-field has been delimited in three individuals ; the posterior 
border has been delimited in five individuals, but the two borders have not been delimited 
together in one and the same individual. 
Anterior Border. 
Example. — M. rhesus. Female, young. The Ist, Ilnd, and Ilird cervical nerves of the 
right side severed in the vertebral canal, but outside the dura mater, at 10 a.m. 'The anterior 
edge of the lower field of response (that of the IVth cervical nerve) can be traced from the mid- 
dorsal line of the scalp at a point corresponding witli the lambda, that is, about i centim. above 
the external occipital protuberance. It sweeps outward at first horizontally to pass close (.5 
