A textbook of obstetrics . Fig. 211.—Vertex presentation, Kit occipitoanterior position. the different positions and presentations of the fetus being readilyunderstood if the typical mechanism of the commonest presenta-tion and position is thoroughly mastered. It is convenient to divide the mechanism o\ labor into anumber of steps or acts, as follows : lirst Step.—Accommodation of the size of the fetal skull tothe size of the pelvic canal by llexion ; accommodation of the shape MECHANISM OF PRESENTATIONS AND POSITIONS. 359 . h. V Fig. 212.—Genital tract with fetus removed, showing divergence o
A textbook of obstetrics . Fig. 211.—Vertex presentation, Kit occipitoanterior position. the different positions and presentations of the fetus being readilyunderstood if the typical mechanism of the commonest presenta-tion and position is thoroughly mastered. It is convenient to divide the mechanism o\ labor into anumber of steps or acts, as follows : lirst Step.—Accommodation of the size of the fetal skull tothe size of the pelvic canal by llexion ; accommodation of the shape MECHANISM OF PRESENTATIONS AND POSITIONS. 359 . h. V Fig. 212.—Genital tract with fetus removed, showing divergence of the pelvicaxis from that of the uterine cavity: </, a, Membranes; /, 6, contraction ring; c, c,point down to winch membranes are unseparated; externum; //.pouch of Douglas;it posterior vaginal wall (elongated and thinned) ; /, rectum ; k, Stretched anal canal ;/, placenta; m, uterovesical peritoneum; ;/, region of os internum (above whichfragments of membranes are found, and below it portions of cervical glands) ; 0, lowerlimit of bladder; />, anterior vaginal wall (not elongated); </, urethra; r, vagina;s, vulva; /, perineum with blood extravasation Barbour and Webster). ,6o THE MECHANISM OF LABOR. of the fetal skull to the shape of the pelvic inlet by molding ; accommodation f the direction of the head to the direction ofthe pel
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Keywords: ., bookcentury1800, bookdecade1890, bookidtex, booksubjectobstetrics
