The Nerves In The Skin

Sources: A Handbook Of Health

How We Tell Things from Touch, and Feel Heat and Cold and Pain. Last

of all, the skin is the principal organ of the sense of touch, and also

of the temperature sense--the sense of heat and cold--and of the sense

that feels pain. All these feelings are attended to by little bulbs

lying in the deeper part of the skin and forming the tips of tiny nerve

twigs,[20] which run inward to join larger nerve branches and finally

reach the spinal cord. There are millions of these little bulbs

scattered all over the surface of the skin, but they are very much

thicker and more numerous in some parts than in others; and that is why,

as you have often noticed, certain parts of the skin are more sensitive

than others. They are thickest, for instance, on the tips of our fingers

and on our lips, and fewest over the back of the neck and shoulders,

and across the lower part of the hips.[21]

For a long time, it was supposed that all these little nerve-bulbs in

the skin did the same kind of work, because they looked, under the

microscope, exactly alike; but it was found that they divide the work up

among them, so that some of them give their entire attention to heat,

and others to cold, others to touch, and others again to pain. So

carefully has the work been mapped out among them that they report to

different centres in the brain and spinal cord, so that we now

understand why, in diseases which happen to attack one or other of these

centres, we may lose our sense of heat and cold, as in that terrible

disease, leprosy; or our sense of touch, as in paralysis; or we may

even, in some very rare cases, lose our sense of pain, and yet have all

our other senses perfect.