Human anatomy, including structure and development and practical considerations . rt in both sexes, pass by tlie rectum so as to compress it. although some enterits walls and mingle with those of the sphincters. Nfrve. —A branch from the sacral plexus {sometimes there are more than one)runs to the levator ani on its u[)per surface. The fibres come from the third antlfourth sacral nerves. Accordinj? to some, the muscle also receives fibres from theinferior hemorrhoidal branch of the jnidic nerve. The coccygeus (Fig. 1424). a triangular muscle arising from the sjjine of theischium and inserted i
Human anatomy, including structure and development and practical considerations . rt in both sexes, pass by tlie rectum so as to compress it. although some enterits walls and mingle with those of the sphincters. Nfrve. —A branch from the sacral plexus {sometimes there are more than one)runs to the levator ani on its u[)per surface. The fibres come from the third antlfourth sacral nerves. Accordinj? to some, the muscle also receives fibres from theinferior hemorrhoidal branch of the jnidic nerve. The coccygeus (Fig. 1424). a triangular muscle arising from the sjjine of theischium and inserted into the border of the coccyx, is in the same plane and practi-cally continuous with the levator ani. The two muscles of both sides have been wellcalled the diap/iroi^ni of the pelvis. They form a funnel-like structure with the wallsconverging downward to the anal canal, and an anterior opening for the prostate inthe male and the vagina and urethra in the female. FlO T4?4 Obturator interims Ischial spine Obturator canal— _ A Cut edge of pelviifascia, wliite line Pubic - Sacrum (cut) Pyriformis ,((>cc\geus \atorani Recto-coccygeal fibres Levator ani (cut) —Rectum Trianjjular ligament, superior layeiTriangular ligament, inferior layer Irethra Bulb of penis, covered by muscleMuscles of pelvic floor from within ; section passed to left of mid-line. Nerve.—The muscle ^:eceives branches from the fourth and fifth sacral nervesand perhaps from the first coccygeal. The external sphincter ani TFig. 1423), situated beneath the skin and car-ried up into the puckering at the anus, is a flat oval muscle comix)sed of striatedfibres surrounding the end of the rectum. It arises from the tip of the coccyx,from the skin over it, and from a raphe extending from it to the anus. The fibresdiverge on either side to enclose the anus, meeting in front of it at the centralpoint of the perineum (page 1917), where they mingle with other muscles whichmeet at that point. Some of the inn
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Keywords: ., bookauthormc, bookcentury1900, bookdecade1910, booksubjectanatomy
