A treatise on the diseases of the nervous system / by William A. Hammond; with the collaboration of Graeme M. Hammond.

  • Hammond, William A. (William Alexander), 1828-1900.
Date:
[1891], ©1891
Catalogue details

Licence: Public Domain Mark

Credit: A treatise on the diseases of the nervous system / by William A. Hammond; with the collaboration of Graeme M. Hammond. Source: Wellcome Collection.

Provider: This material has been provided by the Augustus C. Long Health Sciences Library at Columbia University and Columbia University Libraries/Information Services, through the Medical Heritage Library. The original may be consulted at the the Augustus C. Long Health Sciences Library at Columbia University and Columbia University.

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    continuous state of rigid contraction. As the current of a faradaic battery is a to-and-fro current, running first in one direction and then in the other, it follows that normal muscular tissue must respond instantly to these rapid changes of current in order to continue in a constant state of rigidity. In many forms of paralysis this ability to respond to a rapidly vibrating current is lost. It is therefore advisa- ble, in procuring a faradaic battery, to obtain one which admits of both fine and coarse interruptions. If the galvanic current is used, it will be observed that the muscle to which it is applied only contracts at the making and at the -'breaking of the circuit, or when the strength of the current is suddenly changed. While the current is continuous the muscle remains quiescent. The same results are obtained whether the electrical applications are made to the nerves or to the muscles. The two poles of a battery are known as the anode or positive, and the cathode or negative. In testing the electrical reactions of a muscle, one electrode, the sponge surface of which should be at least two inches in diameter, should be placed on some indifferent part of the body, such as, for in- stance, the sternum, or the skin over some portion of the spine. The oilier electrode should be much smaller and must be provided with an interrupting handle. This electrode is to be applied directly to the motor points of the muscles which are to be tested. By means of a pole-changer attached to the battery either electrode can be made cathode or anode at pleasure. In individuals in a normal state of health muscular contraction, under the stimulation of the galvanic current, follows definite laws. If the weakest current is employed that will cause a muscular con- traction, it is found to take place when the negative pole is applied to the muscle and the circuit is then closed. This is termed the cathodal closure contraction, and is designated by the letters C.C.C. or K.C.C. If the current is increased in Btrength, the cathodal closure contrac- tion will be Stronger, and there will also be a slight contraction if the pole <>n the muscle is made the anode and the circuit is suddenly closed. This latter is known as the anodal closure contraction, and is represented by the letters A.C.C. With increased Btrength of current w are enabled to obtain the anodal opening contraction, A.<>.('., and the cathodal Opening contraction, ('.().('. or K.().('. h will therefore be observed thai in health the cathodal closure contraction is greater 'han the anoda] closure contraction, and the anodal opening contrac- tion is greater than the cathodal opening contraction. The normal reactions, therefore, assuming that a sufficiently pow- erful current is employed, are as follow- ; I. C.C.C. 2. A.c.c. :;. A.O.C. I. C.O.C. When degenerative changes occur in the motor nerves or in the motor cells in the anterior horn of gray inattt r in the spinal cord, the