Our own opinion of the disease is, that it is one of nervous origin, and that the tonic spasm, always present in the muscles of voluntary motion, is only symptomatic of derangement in the great, living electro-galvanic battery, (the brain and spinal cord,) or in some of its wires (nerves) of communication.
Mr. Percival says, "Tetanus consists, in a spasmodic contraction, more or less general, of the muscles of voluntary motion, and especially of those that move the lower jaw; hence the vulgar name of it, locked-jaw, and the technical one of trismus."
In order to make ourselves clearly understood, and furnish the reader with proper materials for him to prosecute his inquiries with success, a few remarks on the origin of muscular motion seem to be absolutely necessary.
It is generally understood by medical men, and taught in the schools, that there are in the animal economy four distinct systems of nerves.
1st system. This consists of the sensitive nerves, which are distributed to all parts of the animal economy endowed with feeling; and all external impulses are reflected to the medulla oblongata, &c. (See Dadd's work on the Horse, p. 127.) In short, these nerves are the media through which the animal gets all his knowledge of external relations.
2d system. The motive. These proceed from nearly the same centre of perception, and distribute themselves to all the muscles of voluntary motion. It is evident that the muscle itself cannot perform its office without the aid of the nerves, (electric wires;) for it has been proved by experiment on the living animal, that when the posterior columns of nervous matter, which pass down from the brain towards the tail, are severed, then all voluntary motion ceases. Motion may, however, continue; but it can only be compared to a ship at sea without a rudder, having nothing to direct its course. It follows, then, that if the nerves of motion and sensation are severed, there is no communication between the parts to which they are distributed and the brain. And the part, if its nutritive function be also paralyzed, will finally become as insensible as a stone—wither and die.
3d system. The respiratory. These are under the control of the will only through the superior power, as manifested by the motive nerves. For the animal will breathe whether it wishes to or not, as long as the vital spark burns.
4th system. The sympathetic, sometimes called nutritive nerves. They are distributed to all the organs of digestion, absorption, circulation, and secretion. These four nervous structures, or systems, must all be in a physiological state, in order to carry on, with unerring certainty, their different functions. If they are injured or diseased, then the perceptions of external relations are but imperfectly conveyed to the mind. (Brutes have a mind.) On the other hand, if the brain, or its appendages, spinal marrow, &c., be in a pathological state, then the manifestations of mind or will are but imperfectly represented. Now, it is evident to every reasonable man, that the nerves may become diseased from various causes; and this explains the reason why locked-jaw sometimes sets in without any apparent cause. The medical world have then agreed to call it idiopathic. This term only serves to bewilder us, and fails to throw the least light on the nature of the malady, or its causes. Many men ridicule the idea of the nerves being diseased, just because alterations in their structure are not evident to the senses. We cannot see the atoms of water, nor even the myriads of living beings abounding in single drop of water! yet no one doubts that water contains many substances imperceptible to the naked eye. We know that epizoötic diseases are wafted, by the winds, from one part of the world to another; yet none of us have ever seen the specific virus. Can any man doubt its existence?
Hence it appears that diseases may exist in delicately-organized filaments, without the cognizance of our external perceptions.
It is further manifest that locked-jaw is only symptomatic of diseased nervous structures, and that a pathological state of the nervous filaments may be brought about independent of a prick of a nail, or direct injury to a nerve.