Injuries of nerves and their consequences - Reflex Sympathetic ...

CHAPTER 11.
ANATOMY OP NERVES.
Structure of nerves. — The nervous system consists essentially
of receptive or controlling ganglionic centres, and
of the nerves which connect these with one another and
with the skin, muscles, and viscera. Kerves are usually
divided into those known as cerebro-spinal and those belonging
to the great sympathetic system. The former
chiefly concern us at present, since, indeed, the latter are
rarely injured, and since their diseases have only of late
begun to claim attention. The former, often known as
nerves of animal life, are such as emerge from the encephalon
or from the spinal axis, and carry to every part of
the body excitations originating in the great centres, or
in turn bring to these the numberless impressions arising
from without, or having birth within the tissues themselves.
Yet, varied as seems to be the character of the
messages with which they are charged, an astonishing
sameness of structure marks the organization of all these
fibres.
The encephalic nerves have certain peculiarities of
origin and of exit which we may have further occasion to
mention in connection with the forms of injury to which
these trunks are liable.
The spinal nerves arise from either side of the medulla
by two roots, distinguished as anterior and posterior, each
having a number of rootlets. Those which form the posterior
root pass through a small ganglionic enlargement ;
those of the anterior stem unite without passing into a
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