A system of practical medicine . nosmia is sometimes present, andthe centre is supposed to be in the uncinate gyrus. TreatiMENT.—The treatment of anosmia depends on the due to nerve disease it is unsatisfactory unless syphilis is thecausal agent. Strychnine may be tried, and is known experimentallyto stimulate the nerve. DISEASES OF THE OPTIC NERVE. The Optic this section we can only deal with certain aflPcctions of the nerveof special interest to the physician. The fibres from each ojitic nerve ])ass back to the chiasm, where a DISEASES OF THE OPTIC NERVE. 39 partial decus
A system of practical medicine . nosmia is sometimes present, andthe centre is supposed to be in the uncinate gyrus. TreatiMENT.—The treatment of anosmia depends on the due to nerve disease it is unsatisfactory unless syphilis is thecausal agent. Strychnine may be tried, and is known experimentallyto stimulate the nerve. DISEASES OF THE OPTIC NERVE. The Optic this section we can only deal with certain aflPcctions of the nerveof special interest to the physician. The fibres from each ojitic nerve ])ass back to the chiasm, where a DISEASES OF THE OPTIC NERVE. 39 partial decussation takes place. The fibres passing to the optic tract arederived from the temporal side of the retina of the same eye and thenasal half of the opposite eye ; the fibres from the nasal portion ofeach retina are placed toward the centre, whilst those from the temporalportion are situated at the periphery of the chiasm. A reference to thediagram will render this arrangement clear. The optic tracts pass to Fig. 1. Optic Tracts. <^Lateral Corpus Geniculatujn Corpora Quadrigeminc OccipitalCortex Diagram of optic nerve and visual tract (Oberstein). the nuclei in the posterior part of the optic thalami, and thence to theoccipital cortex. Etiology.—Disease may attack separately the optic nerve, chiasm,or tract. These parts may all be damaged by tumors, which is by fiirthe most frequent cause, or by meningitis, syphilitic lesions, or hem-orrhage. The nerve may suffer from disease at the back of the orbit or withinthe skull. Rheumatic neuritis following exposure, sometimes associatedwith neuritis of other cranial nerves, is a rare affection. Unilateral blindness sometimes follows severe head injuries, and isprobably due to laceration or hemorrhage. The chiasm often suffers in tumors of the pituitary body and in the 40 DISEASES OF THE PERIPHERAL NERVES. enlargement of this structiuT in acromegaly. Lying on the floor of thethird ventricle, it has been compressed in cases of hydro
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