Organic and functional nervous diseases; a text-book of neurology . temperature in the left hand), the effect of pain upon the color of theface and the size of the pupil, the red cheek on the affected side inpneumonia, the occurrence of glycosuria during sciatica,—are all in-stances of such reflex acts. Many vaso-motor affections are producedby irritation causing reflex effects at a distance from the seat of irrita-tion—a fact always to be kept in mind. The utility of counter-irri-tation to the surface in diseases of the internal organs is explained bysupposing that vascular changes are produc
Organic and functional nervous diseases; a text-book of neurology . temperature in the left hand), the effect of pain upon the color of theface and the size of the pupil, the red cheek on the affected side inpneumonia, the occurrence of glycosuria during sciatica,—are all in-stances of such reflex acts. Many vaso-motor affections are producedby irritation causing reflex effects at a distance from the seat of irrita-tion—a fact always to be kept in mind. The utility of counter-irri-tation to the surface in diseases of the internal organs is explained bysupposing that vascular changes are produced in those organs throughreflex mechanisms set in action by the local irritation. While someof these reflexes may have their central mechanism in the local ganglia,it is probable that the majority are to be traced to the spinal is believed that the sympathetic ganglia are not the seat of reflex centres. Fig. 319. Vaso-dilating nerves to the cutaneous vessels ? • Vessels of the skin and surface • Blister applied to chest-wall ? Thoracic wall -. _Vaso-motor centre. Afferent nerves. Vaso-contracting nerves for the ves-sels of the of the lung. Diagram to represent the Mode of Action of Counter-irritants applied to the Chest (Lauder Brunton).The Irritation of the afferent nerves by the blister on the chest wall gives rise to a vaso-constrictorreflex in ths vessels of the lung. Since the vaso-motor nerves are connected almost exclusively withthe dorsal portion of the spinal cord, it is very natural to conclude that PHYSIOLOGY. 923 the vaso-rootor reflex centres are situated in this region; and thehypothesis has been advanced by Jacubovitch, and strongly urged byGaskell, that the cells of the vesicular columns of Clarke, which arepeculiar to this region, are the seat of these reflex mechanisms. Thishypothesis gains some support from the pathology of this disease the gray matter surrounding the central canal and thevesicular columns is de
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