EXAMINATION OF SOME SPINAL NERVES m 
upper half of the rorearm, on the extensor aspect behind the prominence of the radial extensors 
of the wrist, but somewhat nearer the radial than the ulnar border. 
The spinal nerve-fields arising from it in front are the IVth, Vth, Vlth, Vllth, and, in part, 
the Vlllth cervical, and from it behind arise the Ilird, Ilnd, and 1st thoracic, and, in part, the 
Vlllth cervical. 
These great ventral and dorsal lines lie presumably along the centres of the primitive or 
true ventral and dorsal surfaces of the limb. As regards the primitive position of the forearm 
and hand, it is shown by the skin-fields of the spinal nerves to be that of supination. The skin 
of the pollex is shown to be segmentally anterior to that of tlie middle finger, that of the middle 
finger to that of the minimus. In the skin of the chest, just above the nipple, it is evident there 
is a meeting-place of spinal nerve-fields, which, segmentally considered, lie wide apart ; the Ilird 
thoracic there meets the IVth cervical, or, in some individuals, the IVth thoracic there meets the 
Vth cervical. Where are the intervening nerve-fields to be sought r In part in the muscular 
tissue lying beneath the skin in this region ; but as regards skin, they are to be found in the limb 
proper, and the midmost of the fields, i.e., the Vlllth cervical, is placed almost entirely in the 
hand and forearm, that is, lies widely separated from the trunk, being confined to the apex of the 
limb. These lines of shed between anterior and posterior groups of skin-fields descend behind 
and in front of the shoulder along approximately the middle of the extensor and flexor aspects of 
the upper arm, and to a certain distance down the similar aspects of the forearm. In fore-limb, 
as in hind-limb, the skin of the anterior side of the limb is found to be segmentally rather more 
extensive than that of the posterior side, that is to say, those segments participate in it. In the 
musculature the preponderance of the segmental length of the anterior aspect over that of the 
posterior is still further marked. 
As in the hind-limb, so in the fore-limb, the quinquefid digital partition of the free end of 
the limb is [contra Goodsir) no indication of the number of segments in the limb, or even in the 
free end of the limb, or even of the skin-fields or spinal nerve-fields in the free end of the limb. 
The number of spinal segments contributing to the limb is at least eight (apart from intrusions 
from the sympathetic) ; the number of segments in the free end of the limb, i.e., hand, is four ; in 
the skin of the hand usually three, never five. 
As remarked above, these dorsal and ventral lines of the skin of the limb are not hypo- 
thetical. In proof of this I have sliown that the skin markings of certain animals — Tiger, Zebra, 
Ass, &c. — reveal them and stand in obvious relation to them. They have further considerable 
practical importance from the possibility that they, unlike other skin points, do not shift in 
segmental position with post-fixture and pre-fixture of the flexures. As far as my observations on 
this point go, they indicate that these dorsal and ventral lines remain steadfast, although with 
post-fixture and pre-fixture the skin-fields meeting at them are shifted. 
In comparing the segmental structure of the brachial limb with that of the pelvic limb, 
certain points of resemblance are salient. One of these is the curiously similar distribution of 
the Vlllth cervical and the Vlth lumbar nerves in the two limbs. Each of these nerves supplies 
in its respective limb the skin of the whole of the rree apex of the limb (hand, foot), together 
