Electro-physiology and electro-therapeutics : showing the best methods for the medical uses of electricity / By Alfred C. Garratt.

lean, yet rich in nerve fibrils ; as, for instance, on the muscle tra- pezius, or the pectoralis major. Here we can generally cause one or more bundles or layers to play at will, and this is the species of phenomena to which Dr. Duchenne refers, to prove the direct in-working of the Faradaic current through the mus- cle fihres, independent of the nerves; for he advocates the doc- trine of Hallerian irritability. If we test the muscle biceps brachii with moderate, i. e., painless Faradaic currents, we obtain scarcely any visible effects by placing both the electrodes on the ends of the muscle fibres ; in no case, however, do we thus effect a perfect persistent con- traction, or even a bending of the forearm. But if, now, with- out increasing the strength of the same current, we remove the electrodes, and place one on the middle of this muscle, while with the other we seek the point where the musculo-cutaneus nerve goes behind the muscle,— this taking place, as is well known, in the region of the upper quarter of the inner border of this muscle, — it may happen that instead of obtaining the expected contraction of this muscle, and consequent bending of the forearm, we produce effects on the muscle pronator teres, or even on the flexors of the fingers. When this is the case, we know that the electrode was too far back, and the current has therefore touched the nerve mediamis; or we may even obtain an action on the muscle triceps when the current has reached the nerve radialis. In either case we must move the electrode a little forward and upward, when we shall find that point out of which a fair contraction that flexes the forearm can be pro- duced, and that ivithout the least pain, if no large branches of skin nerves are embraced by the electrodes. Again, if we make a similar trial on the muscle trapezius by placing one electrode just beneath the occiput, so as to rest upon the upper end of this muscle, while the other electrode is planted over its insertion in the spina scapula, and consequently in the direction of the muscle fibres, we obtain no effects of im- portance, except an aching pain in the shoulder blade, or in the occipital region, i. e., if an occipital nerve has been touched by the current. But if we now leave either one of the electrodes 25