The involuntary nervous system / by Walter Holbrook Gaskell.

  • W. H. Gaskell
Date:
1920
Catalogue details

Licence: In copyright

Credit: The involuntary nervous system / by Walter Holbrook Gaskell. Source: Wellcome Collection.

    23/200 page 7
    Fig. I.—The Reflex Paths of tfie Voluntary System in the Cranial Region. The afferent receptor neurons are shown in blue, the connector neurons in black, the efferent excitor neurons in red. This scheme of colouring holds for all the figures in this book. The splanchnic excitor neurons are shown in the lower part of the diagram ; the somatic excitor neurons in the upper part. The receptor neurons for both systems all run in the fifth and tenth nerves which are shown in the lower part of the diagram. The neurons in a vertical line all belong to the same segment, the first six lie in the prosomatic segments, and the remainder in the mesosomatic. The receptor fibres of the somatic system all run in the fifth nerve, their nuclei lying in the Gasserian ganglion, G. G. The ascending sensory root, A.S.V., supplies the connector neurons of the prosomatic segments of the somatic system. These connector neurons, which lie close against the ascending root, communicate with the excitor neurons of the four segments comprising the nucleus of the third nerve, with the nucleus of the fourth nerve, and with the anterior portion of the nucleus of the sixth nerve in the respec¬ tive segments. The descending sensory root, D.S. V., communicates with the con¬ nector neurons of the mesosomatic segments of the somatic system. The connector neurons connect in the first mesosomatic segment with the more posterior portion of the excitor nucleus of the sixth nerve and the others with the series of nuclei which form the excitor nucleus of the twelfth nerve. The receptor fibres of the splanchnic system in the prosomatic region all run in the fifth nerve. They form part of the ascending sensory root and connect in each segment with connector neurons which in their turn connect with the nuclei of the descending motor root of the nerve, D.M. V. The nuclei of the two posterior seg¬ ments form the nucleus masticatorius, N.M. Some afferent fibres of the fifth nerve probably connect also with the connector neurons of the seventh nerve as shown in the diagram. The afferent fibres of the mesosomatic segments of the splanchnic system all run in the sensory portion of the tenth nerve, their cells lying in the vagus gan¬ glion, V. G. A small ascending root connects with the connector neurons of the first three segments ; the connector neurons in their turn connect with the motor nuclei, the first two of which give origin to the seventh nerve and the third to the ninth nerve. The descending root, the fasciculus solitarius, F.S., connects with the connector neurons of the remaining segments which lie in the dorsal nucleus of the vagus, D.N.X. The motor neurons of these segments form the motor portion of the tenth nerve, the segmental nuclei lying in the nucleus ambiguus, N.A.
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