The diagnosis of nervous diseases.

  • Purves Stewart, James, Sir.
Date:
1911
Catalogue details

Licence: In copyright

Credit: The diagnosis of nervous diseases. Source: Wellcome Collection.

Provider: This material has been provided by UCL Library Services. The original may be consulted at UCL (University College London)

    14/508 (page 2)
    o LI NERVOUS DISEASES exerts a trophic influence over the nerve-fibre and is intimately concerned with its nutrition, so that the nerve-fibre degenerates if separated from its tropliic nerve-cell. In a reflex motor act, which is the simplest manifestation of nervous energy, as for example in the plantar reflex, the impulse or stimulus starts from a sensory end-organ, in this instance the skin of the sole. The impulse travels up a sensory nerve-fibre, through the corresponding posterior nerve-root into the spinal cord, and there, through the intermediation of another inter-com- municating nerve-fibre and cell in the grey matter of the cord. FiG'. ].—Di!i!:fi;iiii of a Simple Spinal Reflex. it reaches an anterior cornual cell. From this motor-cell an efTerent impulse starts, travelling outwards along an anterior nerve-root into a peripheral nerve and thus reaching a muscle-fibre in the flexor muscle of the toes. The muscle contracts and with- draws the sole of the foot from the original irritant. The accompanying diagram (Fig. 1) will serve to recall the chief components of a simple spinal reflex, such as we have just described. Some reflexes occur unconsciously, as for example the reflex contraction of the pupil when the retina is stimulated by light, or again, the normal movements of the stomach and intestines. But in other cases the afferent impulse, besides exciting a reflex motor action, sends part of its impulse upwards to the higher centres of the opposite cerebral cortex, where it produces a con- scious sensation. This is accomphshed by means of a sensory fibre