FIG. 55.
c, trophic cell for nerve; a, cerebral fibre; b, trophic cell for muscle; d, ganglionic cell; s, sensory fibre; f, trophic path to muscle; m, muscle. (From Ziemssen's Handbuch der Speciellen Pathol., Bd. xi. Zweite H., Zweite Abtheil, p. 313.)
Duchenne and Joffroy128 also argue the existence of special trophic nerve-cells. The absence129 of the nutritive lesions of the skin and cellular tissue which are so conspicuous when the gray matter around the central canal or posterior to it is involved,130 the dependence of the nutrition of the motor apparatus, nerves, muscles, bones on the integrity of the anterior horns, are facts which, taken together, seem to indicate that the maintenance of nutrition depends on the unbroken continuity of the motor or sensory apparatus from the periphery to the ultimate central element, rather than on any special central cells endowed with trophic functions.131 Erb's hypothesis, as his own scheme moreover denotes, demands not only trophic cells distinct from motor cells, but separate trophic cells for the muscles, for the motor, and for the sensory nerves.
128 “De l'Atrophie aigue et chronique des Cellules nerveuses,” Arch. de Phys., No. 4, 1870.
129 Money, and also Gowers, have signalized a condition of the skin resembling myxœdema (Tr. Path. Soc. London, 1884, and Brit. Med. Journ., 1879).
130 Mayer (Herman's Handbuch Physiol.) sums up the great mass of evidence now accumulated, which demonstrates the trophic influence of the central gray mass of the cord upon the tissue.
131 Nepveu (La France médicale, 1879) mentions some cases of infantile paralysis complicated with trophic lesions of the skin. The facts, if accepted, could only indicate an extension of the myelitis to the central and posterior regions of the gray columns. The relations between non-atrophic paralysis caused by interruptions of the motor tracts and muscular atrophy dependent on lesion of the anterior cornua are exquisitely shown in a case reported by Sander. An adult suffered from chronic motor paralysis, gradually increasing, in the right arm, with paresis of the lower extremities. In the hand, arm, and shoulder the paralysis was followed by gradual atrophy and diminution of the faradic contractility; in the lower extremities no atrophy occurred. At the autopsy was found a gliomatous tumor seated in the anterior cornua predominating on the right side, extending from the level of the sixth dorsal to that of the eighth cervical vertebra. The ganglion-cells were pigmented and compressed, not altogether destroyed. The lumbar cord was intact, and the non-atrophic paresis of the lower extremities evidently resulted from the interruption of the motor tract above.
The peculiar grouping of nerve-centres within the cord that seems to be indicated by some of the groupings of infantile paralysis shows, as has been said, a probable divergence within the cord of nerve-fibres which run together in the same nerve-stem. The associations to be expected from the data of functional association and of clinical history are by no means fully decided. It is even a matter of dispute whether the tibialis anticus is functionally more associated with the flexors or with the extensors of the thigh, and whether its experimental irritation or clinical paralysis really coincides with that of the first or of the second group. This entire field of observation is new and promises fertile results.132