妇产科学课件 正常分娩（英文）.ppt

* * Three anteroposterior diameters of  the pelvic inlet * The smallest plane of the pelvis, particular importance in obstructed labor. ?Anteroposterior diameter of mid pelvis：average 11.5cm. ?Transverse diameter of mid pelvis：alse be called interspinous diameter,average 10cm. Pelvic midplane * Anteroposterior diameter of mid pelvis Transverse diameter of mid pelvis * Transverse diameter of the midpelvis * Four diameters: ?Anteroposterior: diameter of outlet： 11.5cm。 ?Transverse outlet： the distance between the inner edges of the ischial tuberosities。9cm ?Anterior sagittal diameter：6cm。 ?Posterior sagittal diameter ：8.5cm。 Pelvic outlet plane * 4 1、Transverse outlet 2、 Anterior sagittal diameter 3、 Posterior sagittal diameter 4、 Anteroposterior diameter of outlet * * Pelvic axis and inclination of pelvic Pelvic axis：The axis of the pelvis refers to the curve of the birth canal as described by a line drawn through the center of each of the four planes Inclination of pelvic :The angle of the pelvic inlet plane with ground level when women stand.always 60 degree。 * Pelvic axis Inclination of pelvic * * The soft part of the birth canal Formation of lower uterine segment、cervix、 vagina 、soft tissue in the floor of pelvis. * The lower uterine segment Developed from the isthmus of the uterus of nonpregnant women. Physiologic retraction ring : The actively contracting upper segment becomes thicker as labor advances,the lower uterine segment is relatively thin compared with the upper segment,between them a physiologic retraction ring appear. * * Changes of cervix Effacement of cervix dilatation of cervix The upper segment contracts, retracts,and expels the fetus; in response to the force of the contractions of the upper segment, the ripened lower uterine segment and cervix dilate and thereby form a greatly expanded、thinned-out muscular and fibromuscular tube through which the fetus can be ex