Nerves / by David Fraser-Harris.

  • David Fraser Fraser-Harris
Date:
[1928]
Catalogue details

Licence: In copyright

Credit: Nerves / by David Fraser-Harris. Source: Wellcome Collection.

    32/268 page 28
    A wants with him. Now all this is an analogy with what goes on in the nervous system. Let us suppose that A is a spot of skin into which a pin has been stuck, and B is a certain group of muscles some distance from A. Ihe pained spot A sends an urgent message up the nerves to a number of nerve-cells, or to what is called the centre, and from these* roused in this way to activity, issue outgoing currents to the muscles of the group whose contraction constitutes the kick or jerk which the leg or arm gives as the result of that sudden pinprick. Nerve-currents have ascended nerve-fibres or gone in from A, they have aroused a centre C to action, and the centre has discharged nerve-impulses by other nerves to the muscles thrown into activity at B. We see, then, in the first instance, that nerves can convey impulses or at any rate something, from the surface of the body into the nervous system, and, in the next place, that they can carry something out from the nervous system to the muscles at the periphery. Nerve- fibres which convey impulses inwards are called offevent nerves, and nerves which convey impulses outwards are called efferent. Afferent, or ingoing, and efferent, or outgoing, have reference exclusively to the central
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