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OF THE DIVISIONS OF THE HUMAN BODY. 27
panding in its circumference, it draws the parts to which
it is attached together with a power in proportion to the
size of the muscle and the stimulating force applied.
The nervous power has, in fact, more to do with the
force exerted than the strength of the muscle ; and the
force of contraction is often much greater than its own
power of cohesion. I compare
the contraction or drawing to
gether of the particles or disks,
of which the ultimate fibers of a
muscle are composed, under the
nervous influence, to the devel
opment ofthe magnetic attraction
in pieces of iron under the gal
vanic current.
A view of the fascicular arrangement
of the fibers of a voluntary muscle, the
fibers separating at the end into brush-like
bundles of fibrillar. The disk-like forma
tion, of which each ultimate fiber is com
posed, is also exhibited. Very highly
magnified.
Fig. 6
The sheaths of the muscular fibers seem to unite
together, to form the tendons by which they act on
distant parts, when compactness is wanted for use and
as beauty, in the wrist and ankle.
The head alone has seventy-seven muscles. There
are eight for the eyes and eyelids. The eyeball has
four straight muscles, one above, below, and on each
side, and two oblique, to give it a rolling motion. One
of these, before it is attached to the eye, passes through
a pulley, to change the direction of its action. There
are eight muscles for the lips, eight for the jaw, eleven