A groove round the uterus, separating its upper and lower parts, which, in obstructed labour, prevents the baby from moving forward as expected into the cervical canal.
A depression on the surface of the womb that may be detected during labor by applying the hand to the lower part of the abdomen. It occurs in the region of the neck (cervix) of the womb when the circular muscle fibers fail to relax and it indicates the presence of a constriction around the womb, which tends to prevent the infant from emerging into the cervical canal.
A ridge sometimes felt on the uterus above the pubes, marking the line of separation between the upper contractile and lower dilatable segments of the uterus.