affected by tumors or other lesions of the medulla, in association with the root of the pneumogastric; so that symptoms referable to disease of the glosso-pharyngeal alone cannot generally be recognized.

PNEUMOGASTRIC NERVE.

This nerve has both motor and sensory fibres, and is extensively distributed to the pharynx, larynx, lungs, heart, stomach, intestines and spleen. But many of its motor fibres are contributed by the accessory portion of the spinal accessory nerve.

It is liable to still more lesions than the other cranial nerves, from its great extent and varied course-e. g., lesions of its nuclei from degeneration, softening or hemorrhage, generally in association with the adjacent nuclei ; meningitis, syphilis, tumors, or aneurism affecting its roots; in the neck wounds, surgical operations, aneurisms, new growths, or enlarged glands. The last three are frequently causes of difficulty with the pneumogastric in the thorax and the recurrent laryngeals in any part of their course. Diphtheritic paralysis and alcoholic neuritis also affect the functions of the pneumogastric nerve.

If the pharyngeal branches are affected, swallowing is difficult, the food lodges in the pharynx, and small portions or liquids may pass into the larynx and cause choking. If the laryngeal branches are diseased, either in the trunk of the nerve itself, or in the recurrent laryngeal nerve, the various forms of paralysis of the vocal cords, and other parts of the larynx, are produced, which are described in the section on Diseases of the Larynx. Pulmonary branches are both afferent and efferent; of the afferent fibres, some augment, others inhibit, the respiratory centre, and the efferent fibres are said to supply the muscular fibres of the bronchi. But it is only in rare instances that the results of lesions of these fibres are observed clinically. Cheyne-Stokes respiration, and the spasms of hydrophobia, are probably dependent on changes in the respiratory centres, with which the vagus nucleus must be connected. The cardiac fibres have an inhibitory action, and are believed to be inflamed in cases of alcoholic paralysis, when the pulse may become excessively rapid; a similar acceleration has occurred from local disease of the nerve trunk. Some curious cases are on record of slowing of the heart from irritation of the vagus by pressure. Lesions of the gastric branches seem to have caused in different cases pain, vomiting, or excessive appetite; the vomiting frequently observed in cerebral disease must be due to irritation of these nerves.

Treatment must be conducted on the lines indicated in the case of other nerves. (See, also, Diseases of the Larynx.)

LESIONS OF SPINAL ACCESSORY AND HYPOGLOSSAL NERVES.

181

SPINAL ACCESSORY.

The external portion of this nerve arises by a series of roots from the cervical part of the spinal cord, and is really a motor spinal nerve directly connected with the anterior cornua. It is distributed to the sterno-mastoid and trapezius muscles; it is the chief supply of the former, but the latter is largely innervated by cervical and dorsal nerves.

In addition to cervical and intracranial lesions, like those suffered by the vagus, the spinal accessory may be injured by caries of the cervical spine, enlarged glands, or abscesses in the neck, and by direct injury. If the lesion is in the posterior triangle, the sterno-mastoid will, of course, be spared. Paralysis of the sterno-mastoid is shown by the want of prominence due to the contraction of the muscles, and by deficient power of rotation of the head to the opposite side. In paralysis of the trapezius, the natural slope between the neck and the shoulder is lost, and becomes a deep hollow, which is exaggerated when the shoulder is raised, as it still can be by the action of the levator anguli scapulæ. The point of the shoulder lies lower than normal, and the angle of the scapulæ is rotated inward by the unopposed action of the rhomboids and levator. Elevation of the hand above the head is, however, difficult or impossible, because the trapezius does not fix the scapula for the use of the deltoid, nor does it assist in that rotation, for which the serratus magnus is chiefly employed. If the whole muscle is paralyzed, the approximation of the shoulder blade to the spine is incomplete; but in spinal accessory lesions it is chiefly the upper part between the occiput or the acromion that is affected. With a persisting lesion atrophy and electrical changes naturally follow.

Treatment. Here we must deal, where possible, with the causative lesion, and with the muscular failure by galvanic stimulation, and perhaps massage.

HYPOGLOSSAL NERVE.

This nerve, like the last, has a purely motor function, supplying the tongue and most of the muscles attached to the hyoid bone. Its lesions are very similar to those of the two nerves last considered. As the two nuclei are so close to the middle line, they are generally affected together, producing bilateral results. Unilateral paralysis may result from disease above the nucleus, between it and the cortical centre in the ascending frontal convolution; and below the nucleus, from meningitis, simple and syphilitic growths, caries of the cervical vertebræ, and tumors, cellulitis, or injuries beneath the jaw. If it is paralyzed on one side, the back of the tongue on that side is slightly raised from loss of the tonic contraction of the hyoglossus muscle. In the mouth it cannot be moved freely to the same side, but when protruded is pushed to the affected side by the contraction of the posterior fibres

of the genio-hyoglossus, and by the elongating action of the transversus muscle on the healthy side. In bilateral paralysis, the tongue lies motionless in the mouth. Articulation is impaired in proportion to the loss of movement, but very slightly in unilateral disease. Mastication also suffers at the same time. If atrophy supervenes, the tongue shrinks in bulk, feels flabby, and the mucous membrane is thrown into wrinkles. The position of the lesion is suggested by the associated symptoms. If it is above the nucleus, there may be hemiplegic weakness on the same side as the lingual paralysis, but there will not be atrophy; if below the nucleus, atrophy may ensue, and paralysis of the limbs, if any, will be on the opposite side. If bilateral, the lesion is at or near the nuclei, and it is the same if the other lower cranial nerves are involved.

Treatment.-This must follow the causal indications. To galvanize the tongue a spatula may be used, with a wooden handle, and insulated by sealing-wax where it passes over the lips. (Gowers.)

LESIONS OF SPINAL NERVES.

The fibres of the spinal nerves are liable to lesions arising in the spinal cord itself, in the neighborhood of the spinal column, and in the nerve trunks and branches. But, as is well known, all the nerves except the intercostal nerves proceed from plexuses just outside the spinal column, in which the fibres are intermixed, so that isolated nerve paralyses in the limbs are more likely to be caused by lesions below the plexuses, while injuries of the plexuses, or nerve-roots, or spinal cord, are more liable to be followed by grouped paralyses. Disease of the spinal cord of limited extent may lead to isolated paralysis, such as occurs sometimes in progressive muscular atrophy and infantile paralysis.

The lesions of the spinal nerve trunks are mostly injuries from pressure, wounds, fractures, and dislocation in the lower trunks; from new growths, aneurisms, and abscesses in the proximal portions near the spinal column. Exposure to cold, causing neuritis, is occasionally a cause; and the causes of multiple and peripheral neuritis, already enumerated (p. 162), must not be forgotten.

Seeing that most spinal nerves contain both motor and sensory fibres, the symptoms of their disease are both loss of muscular power and anesthesia, determined by the distribution of the nerve-fibres to muscles and skin respectively. If the lesion is persistent, atrophy and altered electrical reactions of the muscle will ensue, and perhaps trophic changes in the skin.

A knowledge of anatomy will be a guide to the recognition of the lesions of these nerves, but some of the more important and frequent may be here shortly described.

PHRENIC NERVE.

The fibres of the phrenic nerve are involved in disease of the cervical portion of the spinal cord, such as acute myelitis; occasionally the nerve is injured by wounds in the neck, and it may be pressed upon by tumors in the neck and thorax. It is not unfrequently involved in diphtheritic and alcoholic paralyses, and in other cases, presumably of multiple neuritis; and it may be affected in lead-poisoning. The characteristic symptom of a bilateral lesion is paralysis of the diaphragm. The breathing is effected solely by the action of the intercostal muscles, and accessory muscles of inspiration; the abdominal wall, instead of advancing during inspiration, is retracted, and it is driven out during expiration. Dyspnoea may be slight when the patient is tranquil, but movement increases the difficulty, and then the over-action of the thoracic walls becomes especially striking. In a less marked stage of paralysis the diaphragm seems to remain in a semi-inspiratory position, not contracting upon the contents of the abdomen, but it resists being drawn up into the chest, so that the abdominal wall is more stationary during respiration. The chief danger of diaphragmatic paralysis is the accumulation of mucus in the chest; a full inspiration is impossible, and so coughing becomes difficult. Moreover, the circulation of the blood must be impeded in the lower part of the lungs, from inaction of the diaphragm, and here the mucus accumulates most abundantly. Any bronchitis, of course, adds to the dangers. Diaphragmatic paralysis, though it sometimes gives the coup de grâce to alcoholic and diphtheritic paralyses, is not necessarily fatal-it may last some days or weeks, and then gradually recover.

POSTERIOR THORACIC NERVE.

This nerve is sometimes injured, as it lies in the posterior triangle of the neck, by carrying loads on the shoulder. The lesion is thus common in porters, etc., and is nine times more frequent in men than women; it also arises from cold, and may be seen in acute spinal paralysis. The paralysis. of the serratus magnus which results is distinguished by the position of the scapula. The inferior angle approaches the spine from the unopposed action of the rhomboidei and the levator anguli scapulæ. The arm is with difficulty raised above the horizontal, since complete elevation is largely effected in health by the serratus magnus rotating the lower angle of the scapula forward. When the arm is moved forward in the horizontal position, the angle of the scapula projects from the chest, so that the fingers can be placed underneath it; and it approaches the spine at the same time. Cutaneous anesthesia is, as a rule, absent, but the onset may be accompanied by neuralgic pains. The digitations of the muscle below the axilla may be obviously wasted or inactive, as compared with the other side.

CIRCUMFLEX NERVE.

Dislocations of the shoulder, falls or blows on the shoulder, and the pressure of a crutch, are the special causes of paralysis of this nerve. In lesions of the brachial plexus, in lead paralysis, and in spinal lesions it may also be involved. It is rarely caused by cold. The chief symptom is paralysis of the deltoid muscle, so that the arm cannot be raised to the horizontal position; any attempt results in elevation of the shoulder by the trapezius and serratus, while the arm hangs vertically. In old cases, atrophy and reaction of degeneration supervene. Cutaneous anæsthesia is often absent, and paralysis of the teres minor, also supplied by the circumflex, cannot generally be recognized. It must be remembered that ankylosis of the shoulder-joint fixes the arm in the same position, and leads to atrophy of the muscle. Passive motion will distinguish between them.

MUSCULO-SPIRAL NERVE.

This nerve, from its exposed position as it winds round the humerus, is especially liable to injury from prolonged pressure, from the use of a crutch, or from hanging the arm over the back of a chair during sleep, or from sleeping with the whole weight of the body upon one arm. It may be also injured by fractures and dislocations, and rarely by violent action of the triceps. Cold is not a common cause. A partial affection of the branches of the musculo-spiral nerve is the characteristic feature of chronic leadpoisoning. The muscles paralyzed by a lesion high up are the extensors of the elbow and wrist, the long extensors of the finger and thumb, and the supinators; but in the more common lesions a little above the elbow one or more muscles escape, especially the triceps and the supinator longus. paralysis of the triceps there is inability to extend the forearm on the arm. This must be tested with the arm raised, so as to avoid the action of gravity in extending the forearm. The extensor paralysis of the wrist and fingers is shown by the "dropped wrist" or "dropped hand." If the forearm is extended in pronation, the hand hangs vertically, and cannot be raised, nor can the fingers or thumbs be lifted from their pendant position. If the hand be raised and the first phalanges be supported, the middle and terminal phalanges can then be extended by the action of the interossei and lumbricales. The supinator paralysis prevents any movement from the position of complete pronation, but if the forearm be flexed, supination will be effected by the biceps. Flexion in semi-pronation is weakened by the absence of the supinator longus, and the characteristic prominence of this muscle in movements of the flexion is absent. Flexion of the fingers is considerably weakened by the passive approximation of the ends of the muscles, and a curious prominence forms on the back of the wrist, which is possibly due,