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the outer border and toes of the foot and in the region of the anus. There are total vesical and rectal paralysis and loss of sphincter reflexes. The patellar reflex is preserved because the lesion is situated lower than the reflex arc.

(e) Lesions in the Cauda Equina.-The symptoms are, in the main, those of a lesion in the lumbosacral enlargement, as the cauda contains all the nerve tracts which begin at that point. If those fibers of the crural nerves that are the highest in situation escape, the paralysis will appear chiefly in the muscles supplied by the sciatic nerves

that is to say, there will be a flaccid paralysis of the peronei and other muscles of the leg and of the small muscles of the foot (sometimes also of the flexors of the thigh and of the glutei). Sensation is disturbed in the region supplied by the sciatic and sacral nerves. There is complete paralysis of the bladder and rectum if the nerves of these organs are involved. The patellar reflex will be preserved if the roots of the crural nerves are unaffected, otherwise it will be abolished. The Achilles tendon reflex and the sphincter reflex are abolished.

If the posterior roots at the corresponding levels are involved in the spinal lesion, violent neuralgic pains will appear in the region of their distribution; sometimes these pains correspond only to the highest roots affected by the disease. Not infrequently reflex muscular twitchings in the paralyzed limbs are observed in such cases.

C. Symptoms Observed in Lesions of the Peripheral Nerves.

Lesions of the peripheral nerves are followed by motor and sensory disturbances which correspond exactly to the region of their distribution; hence a knowledge of these symptoms is indispensable for an exact diagnosis. (See Plate 27.)

The paralysis is flaccid in character, and the muscle undergoes degenerative atrophy if the lesion is severe

(peripheral neuron). The sensory disturbances are strictly confined to the distribution of the cutaneous nerve (in longstanding conditions the boundaries tend to become indistinct). Painful and abnormal sensations are often complained of (paresthesia, formication, pricking sensations, furry feeling, burning, etc.). The reflexes are diminished or lost if their corresponding arcs are included in the damaged nerves.

I. Plexus Paralyses.-The symptoms of plexus paralyses are made up of a mixture of the paralytic symptoms of all the nerves which compose them; the clinical picture, therefore, presents many variations. Some of the most typical and frequent lesions are the following: (a) Erb's Paralysis of the Brachial Plexus.-This involves the fifth and sixth cervical roots, destruction of which is followed by paralysis and atrophy of the deltoid, biceps, brachialis anticus, supinator longus, supra- and infraspinatus. Accordingly, there is inability to raise and abduct the arm or to flex the forearm.

(b) Paralysis of the Lower Portion of the Brachial Plexus. This involves the eighth cervical and first thoracic roots, and leads to paralysis and atrophy of the small muscles of the hand and anesthesia in the ulnar region. In addition there may be, if the first dorsal segment is involved, oculopupillary symptoms, as miosis, diminution in the palpebral fissure, retraction of the bulb. The lower extremities are not involved, the paralysis differing in this respect from that observed in lesions of the corresponding segments of the spinal cord.

II. Lesions of the Cranial Nerves.-The distribution of the sensory disturbance for the various nerve trunks is shown in Figures 23 to 25. The symptoms in lesions of the individual nerves are the following:

1. Olfactory Nerve.-Anosmia of the corresponding half of the nose and parosmia (disagreeable odors).

2. Optic Nerve.-Amaurosis of the corresponding eye and of the entire visual field, differing in this respect from

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disease of the optic tract, in which there is hemianopsia, or loss of vision in one half of the field. In some cases there is only impairment of the visual acuity-contraction of the visual field and atrophy of the optic nerve (white papilla), mydriasis, and reflex pupillary rigidity, while sensual reaction is preserved.

In lesions of the chiasm there is bitemporal hemianopsia (destruction of

the internal retina bundles which decussate at this point).

3. Oculomotor Nerve. -Ptosis (paralysis of the levator palpebræ superioris); inability to rotate the eye inward and upward (internal rectus; superior and inferior oblique); crossed diplopia; fixation of the bulb in downward and outward rotation, owing to contracture of the intact external rectus. Further, there are pupillary rigidity and dilatation(mydriasis), due to interference with the action of the sphincter muscle, and loss of accommodation for near objects on account of paralysis of the ciliary muscle.

4. Trochlear Nerve.-Diplopia in looking downward (superior oblique).

5. Trifacial Nerve. (a) Supra-orbital Branch.-An

esthesia in the skin of the brow and bridge of the nose and of the conjunctiva. (See Fig. 23, V1.)

(b) Infra-orbital Branch.-Anesthesia of the skin on the cheeks and alæ of the nose, anesthesia of the palate and disturbance of the sense of taste (Fig. 23, V2).

(c) Inferior Maxillary Division.-Anesthesia of the skin over the lower jaw and of the mucous membrane of the

Fig. 24.—m, Median; u, ulnar; r, radial; rp, posterior root; ii, ilioinguinal; sp.e, external spermatic.

tongue and mouth (Fig. 23, 13). Disturbance of the sense of taste in the anterior segment of the tongue; paralysis of the muscles of mastication and disturbance in salivary secretion; trismus (spasm of the muscles of mastication due to irritation). Irritation of the sensory branches gives rise to trifacial neuralgia of greater or less

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extent, according to the seat of the lesion; paresthesia also

occurs.

6. Abducens Nerve.-Inability to rotate the eye outward (external rectus); deviation of the bulb inward, and diplopia on the same side when the glance is directed downward.

7. Facial Nerve.-Paralysis of the facial muscles of expression (upper and lower facial), of the mouth, the nose, the orbicularis oculi, and of the forehead. The lines of the face are obliterated; the palpebral fissure can not be closed (lagophthalmus); puckering of the lips, as in whistling, impossible; inability to retract the angles of the mouth, as in laughing.

Paralysis of the digastric (posterior belly), stylohyoid, etc., does not produce any symptoms.

If the lesion is situated within the Fallopian canal, the chorda tympani from the second (third?) branch of the trifacial may be involved and the sense of taste may be disturbed in the anterior segment of the tongue.

The irritative symptoms are: Convulsions of the muscles named, convulsion of the facial nerve, or tic convulsif, and blepharospasm. These symptoms may, however, be due to reflex or central irritation.

8. Auditory Nerve.-(a) Cochlear Nerve.-Deafness, paresthesia.

(b) Vestibular Nerve.-Disturbance of the equilibrium ; attacks of vertigo and vomiting, with tinnitus aurium and whistling noises-Ménière's symptom-complex, especially in hemorrhage in the labyrinth.

9. Glossopharyngeal Nerve.-Partial disturbance of the sense of taste (posterior segment of the tongue); anesthesia of the nasopharynx.

10. Pneumogastric Nerve.—(a) Sensory Branch (True Vagus).-Anesthesia of the pharynx, larynx, esophagus, trachea, and bronchi.

(b) Motor Branch (in part derived from the Spinal Accessory).-Dysphagia (paralysis of the esophagus); dis