the course of the superficial nerves may be marked out by lines of bead-like swellings, as in Fig. 47. The cutaneous neuromata also cause visible swellings. The whole abdomen was covered with such nodules in the case recorded by Smith (Fig. 46). They are sometimes not sensitive, sometimes exquisitely tender and most painful, especially when closely united with the skin. Pressure on the nerve above the

tumour commonly lessens the pain.

Plexiform neuroma rarely causes other symptoms than the signs manifesting its local presence. The functions of the nerve-fibres involved are not usually interfered with. Once or twice anæsthesia of the skin has been observed.

Course. The growth of neuromata varies greatly in rapidity. When symptoms occur they most commonly last for a long time, increasing in severity, and from the long-continued pain the patient may ultimately be worn out. In other cases the symptoms show little tendency to increase, and in rare instances they may lessen in severity and even disappear.

DIAGNOSIS. The recognition of the existence of a neuroma depends on its superficial position, or on the production of symptoms of damage to the nerve. The latter, when existing alone, are equivocal, since they may be due to pressure on the nerve from an adjacent growth, or even to neuritis. The disease may be suspected if symptoms-pain, numbness, weakness-occur, limited to the distribution of a nerve-trunk, and no cause of external pressure can be discovered, and the long course of the symptoms makes it unlikely that they are due to neuritis. The diagnosis can, however, only be certainly made when the tumour can be felt. Secondary subcutaneous sarcomata may very closely resemble neuromata.

The diagnosis of the kind of neuroma, whether "true" or "false," i. e. composed of nerve-fibres or other tissue, is very difficult. Multiple neuromata are usually true, and of very slow growth; false neuromata are rarely multiple unless they are of infecting nature and rapid in development. The existence of idiocy, or other neuropathic indication, is in favour of the neural nature of the tumours. The lateral position of the growth on the nerve is in favour of its "false" character. The diagnosis of plexiform neuroma is only possible when the tortuous nodular cords can be felt.

PROGNOSIS. This depends on the existence of symptoms. If these are absent, unless the tumour is of rapid growth, there is good reason to hope that they will not occur. In multiple (true) neuromata the nerve is less likely to suffer than in isolated growths. If symptoms. are present the prognosis is less favorable, and depends on the tendency which they exhibit to increase.

TREATMENT.-Medicines are useless except in the syphilitic forms of nerve-tumour, not here considered. Extirpation is the only remedy. If the tumour is lateral, and can be shelled out, the removal entails little risk. If, however, the growth infiltrates the substance of the

nerve, the affected part must be excised, and the ends brought together. The risk of permanent loss of function in the nerve is great, and in deciding on such an operation, the urgency of the symptoms, and the importance of the function of the nerve, must be taken into consideration. After the extirpation of such tumours, the tendency of cicatricial processes in nerves to go on to the formation of similar growths (seen in "bulbous nerves") renders the chance of relapse considerable. The operation reproduces conditions favorable for the activity of whatever predisposing influence aided in the original development of the disease. When neuromata are multiple, surgical treatment is out of the question, except for isolated tumours that cause distress.

In the case of terminal neuromata- whether the cutaneous "tuber. cula dolorosa" or the amputation neuromata-excision is practicable, and it is unattended with the risks attending interference with a nerve in its continuity. In amputation flaps the chance of a relapse is considerable.

In plexiform neuroma excision is undesirable, and no other treatment is of any use.

Pain, and the reflex spasm, that are so distressing in amputation neuromata, need relief when attempts to cure have failed. By nervestretching we may perhaps give relief without the effects that follow excision, and in cocaine we have a means of arresting for a time the ingoing impulses that play an important part in generating the symptoms. The rest thus given to the centre is absolute, and its degree and frequent repetition may compensate for its brevity.

DISEASES OF SPECIAL NERVES.

The diseases of the cranial nerves may be most conveniently considered in connection with the diseases of the brain. Here, therefore, only the affections of the spinal nerves will be described, in so far as they present special features. The effect of paralysis of the individual muscles has been already described in detail, and need not be here repeated, except in general terms, or in so far as the association of palsies resulting from a nerve-lesion presents a particular character.

PHRENIC NERVE.-Impaired function of the phrenic nerve is commonly the result of disease of the spinal cord, or of the roots of the nerve from disease of the membranes or the bones. The deep position of the nerve-trunk protects it from injury, but it is occasionally damaged in wounds of the neck, and in its course through the thorax it may be compressed by tumours, aneurisms, &c. Paralysis sometimes follows exposure to cold, and is ascribed to neuritis. This has been

met with in multiple neuritis. In disease of the spinal cord and membranes both nerves are usually paralysed; causes acting on the nerve-trunk usually affect one only. The effect and symptom of paralysis is inaction of the diaphragm (see p. 22). If one nerve only is affected, the diaphragm does not descend on that side, but the movement of the other side lessens the resulting defect of movement, and it can then be detected only by close observation. The loss of the action of the diaphragm has little effect on the respiratory functions while the patient is at rest, but dyspnoea is said to be readily produced by exertion; the breathing then becomes quick and the voice feeble. At the same time this is probably chiefly because too much and too constant work is thrown on the upper thoracic muscle of extraordinary breathing. Any lung disease, such as an attack of bronchitis, is rendered far more serious by the diminished breathing power. When the diaphragm is paralysed, the movement of the thorax is often increased, and the expansion of the lower part may draw forwards the adjacent abdominal wall. This must not be mistaken for the effect of the descent of the diaphragm. Paralysis bas to be distinguished from (1) abnormal nervous breathing. The diaphragm is used little in extraordinary breathing, which is chiefly by the upper part of the thorax, of the "superior costal type," as it is called. Hysterical and nervous patients will often breathe, for a time, only in this manner, even when at perfect rest, especially when they are under observation. Such breathing is no doubt facilitated in women by the fact that the diaphragm is habitually used by them. less than by men. Repeated examination may be necessary to determine whether there is any real paralysis of the diaphragm in these cases. A single diaphragmatic inspiration settles the point. The patient's attention should be distracted, and she should not be aware of the object of the examination. (2) Inflammation of the diaphragm may arrest its movement, and so also may diaphragmatic pleurisy or peritonitis-each distinguished by the fact that it is usually secondary to adjacent inflammation, and any movement, if effected, causes characteristic pain. (3) A primary and isolated degeneration of the muscular fibres of the diaphragm has been described by Callender and others as common after death, but it has not yet been proved to cause such inaction, during life, as might be confounded with paralysis.

Paralysis may be due to disease of the nerve or of the spinal cord. In the latter case other muscles always suffer; in the former the diaphragm usually suffers alone unless it is part of multiple neuritis. In disease of the nerve-roots there are other indications of the position of the disease. The affection is often overlooked because not searched for, especially in disease of the spinal cord. The observer forgets that its associations are not with the lower dorsal muscles, and he omits to look for it in cases in which the cervical cord is suffering and other respiratory muscles act well.

If there is reason to suspect neuritis, counter-irritation should be

applied over the lower and inner part of the anterior triangle of the neck. The only other special point in treatment is the application of electricity. The nerve may be stimulated by pressing the rheophore deeply outside the lower part of the clavicular portion of the sternomastoid. The other pole may be placed at the epigastrium or over the corresponding half of the diaphragm. But the influence of electricity on paralysis of the diaphragm is not sufficient to make its use desirable. In the cases in which such treatment could do good the affection is transient and comparatively unimportant. In central disease electricity has very little influence.

NERVES OF THE UPPER LIMB.

The nerves of the arm and shoulder are derived from the five lower cervical and the first dorsal nerves. These interlace in the brachial plexus in such a complex manner that most of the nerves of the arm are derived from many spinal roots.

The nerve-roots form, by their union, three trunks, which we may indicate by Roman numerals. They are formed thus :-I, by the branch from the fourth, and the roots of the fifth and sixth cervical; II, by the seventh; and III, by the eighth cervical and the first dorsal. Each trunk divides into two parts, and the union of these divisions forms the three cords of the brachial plexus from which the nerves of the arm proceed. But before the primary trunks divide, certain nerves arise, the origin of which is thus less doubtful. The fifth and sixth cervical roots give origin directly to the posterior thoracic nerve for the serratus, and from the cord formed by their union springs the supra-scapular nerve. The three cords of the plexus have the following relations:-The posterior is derived from all three primary trunks, and gives rise to the subscapular nerve, the circumflex, and the musculo-spiral (or radial, as the whole nerve is sometimes termed). The upper or outer cord is derived from the two upper primary trunks, i. e. from the fourth, fifth, sixth, and seventh cervical roots, and from it proceed one anterior thoracic and the musculo-cutaneous nerves, together with the outer head of the median. The inner or lower cord is derived only from the lowest primary trunk, i. e. from the last cervical and first dorsal, and gives rise to the ulnar, the inner head of the median, the internal cutaneous, the intercosto-humeral, and to the second anterior thoracic nerves. It may be convenient to put these coarse anatomical relations in the form of a table.

These anatomical facts, however, give us little help in tracing the relation of the nerves to the spinal roots. The investigations of Ferrier and Yeo,*, who ascertained the movements produced by faradising the several spinal roots in the monkey, show us the way in which the movements, muscles, and nerves are represented in the spinal roots. Their results are therefore of great interest, although we are not justified in transferring the facts to man except in so far as they receive confirmation from human anatomy and pathology. Subject to this reservation, the chief results are important, and may be thus stated.‡

The roots to which the several nerves are thus traced are as follows: Subscapular, 6 and 7 C.; circumflex, 4 and 5 C.; musculo-spiral, 4, 5, 6, 7, 8 C. ; musculo-cutaneous, 4, 5 C.; median, 5, 6, 7, 8 C.; ulnar, 8 C., 1 D.

Still more important are their observations on the relation of various movements of the arm to the nerve-roots, and these are as follows:

Cervical 4-Elevation and retraction of the arm, flexion and supination of the forearm; by the rhomboids, supra- and infra-spinatus, biceps, brachialis, and supinators.

Cervical 5. Similar to the last, but without retraction of the arm, and with extension of the wrist and first phalanges; by the deltoid, serratus, flexors of elbow, extensors of wrist, and long extensors of fingers.

Cervical 6.-Adduction and retraction of the upper arm, extension and pronation of the forearm, flexion of the wrist; by contraction of the pectoralis, latissimus dorsi, triceps, flexors of wrist, pronators.

Cervical 7.-Adduction and rotation inwards at the shoulder-joint, flexion of the wrist, and of the fingers at the second phalanx; by the teres major, latissimus dorsi, subscapularis, triceps, and long flexors of the fingers.

Cervical 8.-Flexion of fingers and thumb so as to close the fist; flexion of wrist towards the ulnar side, pronation of forearm, extension of elbow; by the intrinsic muscles of the hand, the long flexors of the fingers and thumb, the flexors of the wrist, and the triceps.

Dorsal 1.-Adduction of the thumb, flexion of the fingers at the metacarpophalangeal joints; by the interossei, &c.

Thus most movements are related to many spinal roots. The most important relations are these: that of the deltoid, rhomboids, supra- and infra-spinatus, flexors of the elbow, and supinators, to the fourth and fifth cervical; that of the adductors of the arm and extensors of the elbow to the sixth and seventh nerves; pronation to the sixth and eighth; extension of the wrist to the fifth; flexion to the eighth; extension of the first phalanx to the fifth; flexion of the fingers to the seventh and eighth, and the action of the intrinsic muscles of the hand to the first dorsal. These facts will probably, in the future, find important practical applications.

Regarding the relation of the sensory branches to the nerve-roots, we have Proc. Roy. Soc.,' March 21, 1881. Careful dissections by Herringham (cf. March 25th, 1887) give somewhat different results, but this method of investigation is open to more uncertainties than that of stimulation. Herringham's conclusions shoud, however, be noted by future investigators.

In the case of the leg there are some important discrepancies between the results in the ape and the conditions that obtain in man. These will be noticed in their proper place.

Ferrier has since stated that the relations he gave (followed in the text) were all one nerve too high (Proc. Roy. Soc.,' 1883, vol. xxxv, p. 229), but this would make the innervation of the intrinsic muscles of the hand from the second dorsal nerve, which is certainly not the case in man.