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as suggested by Gowers, to the synovial sacs and bones of the carpus projecting in that direction when unsupported by the extensor tendons. If there is cutaneous anesthesia, it affects the outer side of the back of the hand, the back of the thumb, and the back of the first phalanges of the fore and middle fingers.

ULNAR NERVE.

This is exposed to wounds and injuries in the arm, and near the wrist, to dislocations of the shoulder and elbow, and to fractures of the forearm. A neuritis from cold is not common; but the stretching of the nerve at the elbow by extreme flexion of that joint probably sets up neuritis sometimes, especially in those already out of health. The movements affected are flexion of the wrist toward the ulnar side, flexion of the fingers, especially of the first phalanges, with extension of the second and third, adduction of the thumb, and the lateral movements of the fingers by the interossei. In old cases, the unopposed action of the extensor muscles leads to over-extension of the first phalanges, and flexion of the second and third, producing the claw-like hand (main en griffe). Anæsthesia is variable: its limits are the ulnar part of the hand corresponding to one-and-a-half fingers in front and two-and-a-half on the back.

MEDIAN NERVE.

This is mostly affected by injuries, occasionally by neuritis. When it is paralyzed the forearm cannot be pronated more than half-way, flexion of the wrist takes place toward the ulnar side, the thumb cannot be flexed or adducted, the second phalanges of the fingers cannot be flexed on the first, nor the third phalanx on the second, except in the case of the third and fourth fingers, in which this is effected by the ulnar half of the flexor profundus. Anæsthesia, if it occurs, affects the radial half of the palm of the hand, the anterior aspect of the thumb, forefinger, middle finger, and radial side of ring finger, and the dorsal surfaces of the same three fingers (or fore and middle only in some persons).

SCIATIC NERVE.

The most common paralysis in the lower extremity is that due to disease of the sciatic nerve, wholly or in part. It may be from tumors or diseased bone in the pelvis, from dislocations of the hip, from wounds, tumors, or neuroma in the thigh. The external popliteal (peroneal) nerve, like the ulnar, occupies an exposed position near the knee. Neuritis is relatively common, and to this many, if not all cases, of sciatica are to be attributed.

EXTERNAL POPLITEAL NERVE.

Lesions cause paralysis of the tibialis anticus, the peronei, the long extensors of the toes, and the short extensor on the dorsum of the foot. The foot hangs down when raised from the ground (foot-drop), and lies extended when the patient is in bed; dorsal flexion of the foot, and of the toes, and abduction of the foot, and elevation of its outer border are deficient or impossible. Wasting of the anterior tibial muscles, and of the little extensor brevis can be readily recognized by contrast with the other leg; in old cases permanent extension of the foot (talipes) is produced mainly by the action. of gravity, especially when the patient lies in bed. Anesthesia affects the outer half of the front of the leg and the dorsum of the foot.

INTERNAL POPLITEAL NERVE.

Extension (plantar flexion) of the foot and flexion of the toes cannot be effected. The patient cannot raise himself on his toes, nor can he adduct the foot. In old cases talipes calcaneus may develop, and a kind of clawfoot from over-extension of the proximal phalanges, and flexion of the second and third. Anæsthesia corresponds to the outer half of the back of the leg, and the sole of the foot.

In a lesion of the sciatic trunk above the upper third of the thigh, the flexors of the leg upon the thigh are also involved.

SCIATICA.

This has long been regarded as a typical neuralgia involving the sciatic nerve, but the fact, so commonly observed, that in old cases the muscles of the lower extremity waste, shows that there is something more than a pure functional neuralgia; and Dr. Gowers shows that it is, indeed, in the large majority of cases, a genuine neuritis, as proved by the conditions under which it arises; by the accompanying symptoms, anæsthesia, and muscular atrophy; and by the fact that in a few cases post-mortem neuritis has actually been found.

Etiology. The disease is much more common in men than women, and occurs in the latter half of life, especially between the ages of forty and fifty (Gowers). The gouty and rheumatic dispositions seem to render people liable to it, and it is excited by cold in a large number of cases; by various mechanical causes, such as blows, long pressure on the nerve, as by the edge of a chair; by fatigue from excessive walking, or otherwise, and by some diseases within and without the pelvis.

Symptoms. The chief symptom is pain, which is felt in the nervetrunk or its branches; it comes on either gradually or suddenly, and is

aggravated by movement or the attempt to walk, or by anything which causes the nerve to be stretched or pressed upon. To avoid this, the patient holds the leg flexed at the knee when walking, and when lying down the most comfortable position is one of flexion. The pain is most often in the back of the thigh, but may extend down the back of the calf, along the outer side of the leg, and to the sole of the foot; and is often most intense at certain spots, namely, near the posterior iliac spine, at the sciatic notch, about the middle of the thigh, behind the knee, below the head of the fibula, behind the external malleolus, and on the dorsum of the foot. The nerve, too, is tender to pressure, especially at the sciatic notch, along the back of the thigh, and in the external popliteal branch behind the head of the fibula.

The pain is burning or gnawing, more or less continuous, but intensified by movement or manipulation. In severe cases, other disturbances of nervefunction occur. These are tingling, formication, and anæsthesia, in connection with sensory fibres; and atrophy of muscles, muscular weakness, and sometimes fibrillary tremors, from implication of motor fibres. The electrical reactions are not markedly altered except in severe cases, when reaction of degeneration may occur.

The duration is very variable. Slight cases may recover quickly; severer cases last months or years; and after subsidence of the pain, muscular wasting, fibrillary contractions, and a tendency to cramps may persist for some time.

Diagnosis. The diagnostic points in favor of sciatic neuritis are the tenderness of the nerve and the presence of anesthesia and muscular atrophy. These distinguish it from a pure neuralgia of this region, which appears to be rare. Further, it must be distinguished from the pains due to hip-joint disease and pelvic lesions, in which, also, tenderness should be absent, and the pains more limited to the seat of the lesion. But even if neuritis is present, it may be secondary to such lesions, and the symptoms special to them should be carefully looked for before concluding that the disease is a primary sciatica.

Prognosis. This is, on the whole, favorable.

Treatment. Complete rest is essential, in the position that most eases the pain. Any gouty predisposition may be met by suitable remedies, such as saline diuretics and purges. In acute cases-especially those due to cold -hot poultices or fomentations should be applied to the affected limb, and, internally, perchloride of mercury or iodide of potassium. In later stages, both counter-irritants and sedatives are of value. Mustard plasters, blisters frequently repeated, acetic turpentine liniments, and the chloride of methyl spray as recommended by Debove, may all give some relief. This last is only a method of obtaining counter-irritation by temporary freezing of the skin along the course of the nerve. Often the greatest benefit is obtained

from morphia injections, but they must be given with proper fear that a mor phia habit may be subsequently induced. A cocaine injection of 1⁄2 or grain is said to be also efficacious. Belladonna, opium, and chloroform lini ments may be also used, and galvanism in the same way as is described unde neuralgia. Finally, in severe cases, nerve-stretching remains as a means of getting relief, generally for some time, even if the pain subsequently recurs

SPASM OF MUSCLES SUPPLIED BY CRANIAL NERVES.

SPASM OF OCULAR MUSCLES.

This occurs in association with various diseases of the eye, in the conjugate deviation of cerebral disease, in hysteria, and other conditions. Clonic spasm is termed nystagmus. The eyes are moved rapidly to and fro, generally in a lateral direction-sometimes vertically. It results from some ocular defects, such as extreme choroidal atrophy, and albinism. It occurs in a number of central nervous diseases, with greatest constancy in disseminated sclerosis and Friedrich's ataxy, but also frequently in tumors of the cere bellum. It also appears in miners, especially when at work in the recumbent position,

SPASM OF THE JAW.

Trismus, or spasm of the muscles closing the jaw, is one of the first indications of the onset of tetanus. The jaw is fixed by tonic contraction of the masseter or temporal muscles, so that the teeth cannot be separated more than a few lines. A similar spasm may be due to irritation of the teeth, or to stomatitis, or, on the other hand, to central disease, such as disease of the pons in the neighborhood of the fifth nerve nucleus. It must be distinguished from tumors or rheumatic arthritis fixing the jaw-joint. Clonic spasm of the jaw occurs in rigor, in convulsions, and in hysteria-rarely as an isolated phenomenon.

FACIAL SPASM.

Irregular contractions of the facial muscles take place in chorea, and a tonic contraction is a late stage of facial paralysis. Boys and girls often acquire a habit of twitching certain muscles of the face, neck, or other part of the body, and this habit may last into adult life. More serious cases of facial spasm (convulsive tic, histrionic spasm), occur in people over twenty years of age, and mostly between thirty and sixty. In some of these there is actual irritation of the facial nerve by tumors in the pons, or of the facial cortical centre on the opposite side of the brain; in most cases the condition seems to be idiopathic. It is much more frequent in women than in men, and arises from emotion, mental anxiety, irritation of the peripheral branches of the fifth nerve as in the eyelids, or the teeth, and from exposure to cold. The spasm chiefly affects the orbicularis palpebrarum and the zygomatici,

so that the eye is half closed, and the angle of the mouth is drawn up. Other facial muscles, including the platysma myoides, are also contracted, but the orbicularis oris and frontalis muscle, as a rule, escape. The contractions are momentary, and frequently repeated; or the spasm is of longer duration, and recurs at longer intervals; but it causes no pain. The spasm is at first entirely on one side, and only in severe or prolonged cases affects the other side. The electrical reactions are usually normal.

The Prognosis in a well-established case is unsatisfactory; the disease will last months, or years, and even to the end of life.

The Treatment consists in the removal of causes of irritation, if they can be recognized; the use of nervine tonics such as zinc, iron, and strychnine; and of sedatives, especially the hypodermic injection of morphia. A weak galvanic current applied continuously, and counter-irritation by blisters behind the ear, may be tried. Nerve-stretching has been performed in some cases, but only exceptionally with any lasting benefit.

DISEASES OF THE SPINAL CORD.

PRELIMINARY CONSIDERATIONS.

GENERAL EFFECTS OF LESIONS.

Anatomy of the Spinal Cord.-This is at first sight simple: we see on a transverse section two crescents of gray matter, one on either side of the middle line, united by a central gray commissure, and surrounded entirely by white matter. Each gray crescent consists of an anterior, generally larger portion, or cornu (horn) containing motor cells, connected with the anterior roots of the spinal nerves, and a posterior cornu, receiving the posterior roots of the same nerves. The white matter is divisible on each side into an antero-lateral portion, extending from the anterior fissure, round the anterior cornu, to the posterior cornu, and a posterior portion internal to the posterior cornu. This arrangement of white and gray matter is continuous throughout the length of the spinal cord, so that the two substances form a group of columns, of which the white antero-lateral and posterior columns embed, so to say, the gray anterior and posterior columns, always known, however, from their appearance on transverse section, as the gray cornua. Recent researches have shown that the white columns are by no means uniform in structure and function, but must be split up into other smaller columns or tracts.

The posterior column is divisible into an inner portion, the posterior median column, or column of Goll; and an outer portion, the posteroexternal column, or column of Burdach. The antero-lateral column contains

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