A treatise on nervous diseases; their symptoms and treatment . Fig. 7.—Diagram of a horizontal section of the brain, showing the course of thepeduncular fibers. ca, anterior commissure ; i, it, in, the three divisions of lenticular nucleus; pi,pm, pe, the internal, middle, and external portions of the peduncular fibers passingbelow the optic thalamus. Other letters as in Fig. 5. ANATOMY. 25 the inner two thirds of the posterior limb passesthrongh the middle third of the basis, and secondary-degeneration of these fibers can be followed thronghthe pons and medulla into the pyramidal tracts of th
A treatise on nervous diseases; their symptoms and treatment . Fig. 7.—Diagram of a horizontal section of the brain, showing the course of thepeduncular fibers. ca, anterior commissure ; i, it, in, the three divisions of lenticular nucleus; pi,pm, pe, the internal, middle, and external portions of the peduncular fibers passingbelow the optic thalamus. Other letters as in Fig. 5. ANATOMY. 25 the inner two thirds of the posterior limb passesthrongh the middle third of the basis, and secondary-degeneration of these fibers can be followed thronghthe pons and medulla into the pyramidal tracts of thecord. In Fig. 7 this portion of the internal capsule isshaded. Lesion of the outer third of the posteriorlimb of the capsule is followed by no descending de-generation; hence it is supposed that its fibers arecentripetal, and they pass into the corona radiata ofthe occipital Fir. 8.—Diagram illustrating decussation of optic nerves in the chiasms, andthe effect of lesions of portions of the optic tract,o, optic nerves; ot, optic tracts; eg, corpora geniculnta; a, b, c, lesions infront, at side of chiasma, and on optic tract. 26 DISEASES OF TEE BRAIN. The decussation of the optic nerves at the chiasmais only partial. The diagram on page 25 may give anidea of the arrangement of the fibers. The fibers fromthe right optic tract pass to the right side of both reti-nas, the larger portion decussating with those of theopposite side ; and vice versa for those of the left optictract.
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectnervoussystem, bookye
