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margin of the sternomastoid, direct them somewhat inwards, and press firmly.
press firmly. We may in this way be certain not only to excite the phrenic nerves, but also, from the extent of bearing of the electrodes, to produce contraction of the inspiratory muscles supplied by nerves which traverse the path of the current, as well as directly to excite the scalenus anticus and sternomastoid.
The large electrodes are recommended for these, reasons as well as for the greater ease with which we are enabled to hit the phrenics. It is also necessary that the head, shoulders, and arms of the patient should be fixed by assistants, in order that the auxiliary muscles of inspiration, especially the serratus anticus major, and the pectorals, should have fixed points from which they may energetically act upon the chest; and sometimes in order to control disturbing movements of the upper extremities, caused by accidental irritation of the motor twigs proceeding to them from the brachial plexus. The length of each excitation should be that of a quiet deep inspiration, that is, about three seconds. The expiration is best accomplished by an assistant, who makes strong and extensive pressure upon the abdomen in the direction from below upwards. It is necessary to make a pause after a number of excitations, and to observe whether spontaneous respiration will occur.
The duration of such a pause must be governed by the character of the natural respiratory movements. Care must be taken to maintain the conductors in position and well pressed down.
The motor nerves proceeding to the shoulder and thorax from the supra-clavicular portion of the brachial plexus may all be excited under favorable circumstances without the chief trunks of the plexus being involved. In all cases, exact anatomical knowledge, together with experience in faradization and in the use of fine electrodes, is necessary. The trunks of the supra-clavicular part of the brachial plexus are of no avail for the excitation of individual muscles, since the irritation of every single trunk causes the contraction of whole groups of muscles that have generally no harmony of action, but that receive nerve-fibrils from the same
same stem. Whenever the therapeutic value of indirect electrization does not depend upon the excitation of individual muscles, and when the unavoidably painful irritation of the sensitive fibres is unimportant, as, for example, in paralysis of the whole arm, electrization of the brachial plexus, on account of its superficial position, is especially adapted for an unpractised operator.
The Superior Extremity. The axillary and radial nerves are both included in the posterior cord of the brachial plexus, so that by its excitation energetic contraction of the deltoid results, as well as of the muscles supplied by the radial nerve.
The musculo-cutaneous nerve after its passage through the coraco-brachialis is found in the interval between that muscle and the biceps, or further outwards between the two heads of the biceps. Strong flexion of the forearm is the result of its excitation.
The median nerve is accessible along the whole of the furrow by the inner side of the biceps, but with more certainty over the lower third of the humerus, after it has crossed to the inner side of the brachial artery, where it can be compressed against the bone. The result is pain in its sensitive branches distributed to the thumb, fingers, and palmar surface of the forearm, and contraction of the pronator teres, pronator quadratus, radialis internus, palmaris longus, flexor digitorum sublimis and profundus, as well as of the muscles of the ball of the thumb, and of the three first lumbricales. The effects, therefore, are strong pronation of the forearm, bending of the hand towards the radial side and flexion of the fingers with opposition to the thumb. In the forearm, an inch above the wrist, the nerve lies for some distance between the tendons of the palmaris longus and the radialis internus, almost quite superficial. Excitation here produces abduction of the thumb, with stronger opposition and slighter flexion of the first phalanges of the index and middle fingers.
The ulnar nerve may be excited along its whole course from the axilla to the elbow, although by
movement of the skin or of the nerves, an unintentional action of the median is easily produced. It is best to take the interval between the olecranon and the internal condyle, since here the nerve does not slip, but can be pressed firmly against the bone. Its excitation produces pain in the long palmar branch and its twigs to the fingers on the volar and dorsal sides of the hand, with contraction of the ulnaris internus, flexor digitorum profundus, palmaris brevis, muscles of the little finger, interossei, 4th lumbricales and abductor pollicis. After giving off its posterior branches, the nerve lies wholly superficial for a considerable distancce above the wrist on the radial side of the tendon of the ulnaris internus; and it produces when excited here pain in the volar twigs and in the above-mentioned muscles of the hand. The hand is rendered concave, the thumb abducted, the little finger strongly flexed and opposed, and the remaining fingers moderately flexed at the metacarpo-phalangeal articulations.
The radial nerve is accessible at the posterior edge of the axillary cavity, but it is most superficial and more easily compressed on the outer edge of the humerus, where it passes round to the front. The spot is readily found by taking the middle point between the insertion of the deltoid and the external condyle, from this point somewhat outwards. Lower down, between the supinator longus and brachialis internus, it is more deeply placed but is still accessible. Its excitation above the external condyle causes painful sensations in the region of the superficial radial nerve down to the fingers on the dorsal surface, with contraction of the supinator brevis, ulnaris externus, radialis internus, extensor digitorum communis, extensor indicis, extensor minimi digiti, extensor pollicis longus and brevis, and abductor pollicis. It consequently produces supination of the forearm with complete extension of the hand and thumb, and extension of the first phalanges of the fingers.
Excitation of a single internal intercostal muscle may be effected by means of a thin electrode pressed against the lower margin of a rib, close to the insertion of a digitation of the serratus magnus. During quiet respiration we may thus produce a contraction of the muscle from the place of irritation to the junction of the rib with its cartilage, and thereby a strong lifting of the rib below, and in both of them it may be plainly seen and felt.
The abdominal muscles can only be brought into partial contraction by one electrode, since they are supplied by several nerves. The rectus abdominis receives as many nerves as it has fleshy bellies. These nerves enter the muscle at its outer margin, and are only accessible at the point of entrance,