A manual of human physiology, including histology and microscopical anatomy, with special reference to the requirements of practical medicine . does not seem to be a continued toniccontraction of the sphincters. As long as the faeces lie above therectum, they do not excite any conscious sensations, but the sensationof requiring to go to stool occurs, when the faeces pass into the the same time, the stimulation of the sensory nerves of the rectumcauses a reflex excitement of the sphincters. The centre for thesemovements (Budges centrum anospinale) lies in the lumbar region ofthe spina
A manual of human physiology, including histology and microscopical anatomy, with special reference to the requirements of practical medicine . does not seem to be a continued toniccontraction of the sphincters. As long as the faeces lie above therectum, they do not excite any conscious sensations, but the sensationof requiring to go to stool occurs, when the faeces pass into the the same time, the stimulation of the sensory nerves of the rectumcauses a reflex excitement of the sphincters. The centre for thesemovements (Budges centrum anospinale) lies in the lumbar region ofthe spinal cord; in the rabbit, between the sixth and seventh, and inthe dog, at the fifth lumbar vertebra (Masius). In animals, whose spinal cord is divided above the centre, a slight touch in theregion of the anus causes this orifice to contract, but after this lively reflex con-traction, the sphincters relax again, and the anus may remain opeu for a occurs, because the voluntary impulses which proceed from the brain to causethe contraction of the external sphincter are absent. Landois observed, that in 314 EXCRETION OF F/ECAL 2Fig. 129. The Perinseum and its Muscles—1, Anus ; 2, coccyx ; 3, tuberosity; 4, sciaticligament; 5, cotyloid cavity ; B, bulbo-caveruosus muscle ; Ts, superficialtransverse perineai muscle ; F, fascia of the deep transverse perineal muscle ;J, ischio-cavernosus muscle; M, obturator internus; S, external anal sphinc-ter ; L, levator ani; P, pyriformis (Henle). dogs with the posterior roots of their lower lumbar and sacral nerves divided,the anus remained open, and not unfrequeutly a mass of feces remained halfejected. As the sensibility of the rectum and anus was abolished in these animals,the sphincters could not contract reflexly, nor could there be any voluntary con-traction of the sphincters. The external sphincter can be contracted voluntarily from the cerebrum,like any voluntary muscle, but the closure can only be effected up to acerta
Size: 1659px × 1507px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1880, booksubjectphysiology, bookyear1
