Physiology of the nervous system / J.P. Morat.

  • Morat, J. P. (Jean Pierre), 1846-1920
Date:
1914
Catalogue details

Licence: In copyright

Credit: Physiology of the nervous system / J.P. Morat. Source: Wellcome Collection.

    185/716 (page 153)
    of the sensory nerves it would be justifiable to infer the origin of the nervous action; in this case the action would be strongly reflex ; and would be refiected on the skin (Brissaud). Centrifugal cutaneous nerves.—But the posterior roots contain centrifugal fibres ; and it is possible that certain of these fibres proceed to the fixed elements of the skin, just as there are those which go to the glandular cells of this structure. The alteration of these fibres and the perversion of function in the cutaneous covering, which is the result thereof, leads, in the end, to a modification of its structm’e (trophic distm'bance). The areas of these neuro-trophic dermatoses may then be superposed on those of the anaesthetic zones, if, as is probable, the centrifugal fibres of the posterior root have, more or less accurately, the distribu- tion of the centripetal fibres of the same root. Segmentary alterations of sensation and of nutrition.—Trojihic distmbances and partial anaesthesia affect an equally regular form in certain cases, but have an orientation altogether different to that of the preceding. Instead of being zonal, the cutaneous lesions are segmentary. This arrangement is particularly striking in the limbs (dermatoses assuming the form of a glove, that of a sleeve. Fig. 61. Diagram of the metameric and segmentary distribution of the nerves of the upper limb (after Brissaud). The cervical enlargement of the spinal cord is divided by horizontal lines into three metameres to which the roots Ri, R2, R3, going to the thoracic limb, correspond ; by vertical lines into three segments Mb M2, M3, of which the deepest gives off nerves of the arm, the middle one ^erves of the forearm, and the most superficial nerves of the hand. etc.). In order that such forms may be the result of limited lesions of the grey substance of the spinal cord, they must be inscribed there in the arrangement of the origins of the nerves. According to Brissaud, the spinal cord is not only formed of superposed neurotomes (corresponding primitively to the roots super- posed in the same order), but its grey matter presents, in its lateral thickness, superadded layers, which reinforce it at the site of equally superadded portions