Carpenter's principles of human physiology . original figure, after the cessation of the effort by which it has been accom-modated for the distinct vision of near objects, is effected by the relaxationof the ciliary muscle, which permits the elasticity of the suspensory liga-ment to come into play. Under these circumstances the lens (m) becomesflattened, the peripheral margin of the iris is brought forward, the pupil dilatesunder the influence of the dilatator pupilla?, which is innervated by the Sym-pathetic nerve, the tips of the ciliary processes are approximated to the marginof the lens, a
Carpenter's principles of human physiology . original figure, after the cessation of the effort by which it has been accom-modated for the distinct vision of near objects, is effected by the relaxationof the ciliary muscle, which permits the elasticity of the suspensory liga-ment to come into play. Under these circumstances the lens (m) becomesflattened, the peripheral margin of the iris is brought forward, the pupil dilatesunder the influence of the dilatator pupilla?, which is innervated by the Sym-pathetic nerve, the tips of the ciliary processes are approximated to the marginof the lens, and the so-called negative accommodation is effected. The maininstrument in effecting these changes in the Eye appears to be the CiliaryMuscle, the structure and attachments of which were first clearly describedby Mr. Bowman. It consists of unstriped muscular fibre, partly arranged ina circular manner, the innermost fibres (sometimes termed Midlers muscle)running parallel to the margin of the Cornea (rf, Fig. 261), and partly dis- Fig. Section of the Ciliary Region of the Eye inMan. a. Meridianal muscular fasciculi of the musculuciliaris. 5. Deeper seated radiating fasciculi, c c c. Annular plexus, d. Annular muscle of Muscular lamina on the posterior surface of Iris. g. Muscular plexus at the ciliary border of theIris. e. Annular tendon of the musculus ciliaris. h. Ligamentum pectinatum. posed radially (a), the fibres of the latter portion of the muscle appearing tobe connected at their origin with the posterior elastic lamina of the Cornea,and externally or posteriorly being partly inserted into the Iris, forming thepillars of the Iris (Ligamentum pectinatum iridis), partly into the Scleroticbounding the canal of Schlemm (s, Fig. 260), and partly and chiefly into thatpart of the outer surface of the choroid tunic, which corresponds to the ciliaryprocesses. The movement which effects the change of form of the crystallinelens is performed in obedience to Volitio
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectphysiology, bookyear1
