Cutaneous Sensory Fibers and Sensory Conduction

When mechanical, thermal or chemical stimuli of sufficient intensity are applied to the skin, they evoke sensations of pain. At one time it was thought that excessive stimulation of any cutaneous receptor was painful, but this view was abandoned when Donaldson, von Frey and others found that there were definite touch, temperature and pain spots on the skin. According to Adrian,¹"It is now believed that there are special receptors and conductors for pain as there are for touch and temperature, but the specific character of pain, its urgency, massiveness, etc., suggests that the receptors and conductors differ considerably from those of other types of cutaneous sensation." It has been said that there are not enough sensory fibers to supply the entire surface of the body with specific conductors for each of the varieties of cutaneous sensation. Ingbert²made careful counts of the myelinated fibers in the dorsal