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the length of a straight line passing through the center of a circle and connecting opposite points on its circumference; hence the distance between the two specified opposite points on the periphery of a structure such as the cranium or pelvis.
cranial d's (craniometric d's) imaginary lines connecting points on opposite surfaces of the cranium; the most important are biparietal, that joining the parietal eminences; bitemporal, that joining the extremities of the coronal suture; cervicobregmatic, that joining the center of the anterior fontanel and the junction of the neck with the floor of the mouth; frontomental, that joining the forehead and chin; occipitofrontal, that joining the external occipital protuberance and the most prominent midpoint of the frontal bone; occipitomental, that joining the external occipital protuberance and the most prominent midpoint of the chin; suboccipitobregmatic, that joining the lowest posterior point of the occiput and the center of the anterior fontanel.
pelvic diameter see pelvic diameter.
pertaining to the pelvis.
pelvic diameter any diameter of the pelvis. The diagonal conjugate joins the posterior surface of the pubis to the tip of the sacral promontory; the external conjugate joins the depression under the last lumbar spine to the upper margin of the pubis; the true or internal conjugate is the anteroposterior diameter of the pelvic inlet, measured from the upper margin of the pubic symphysis to the sacrovertebral angle; the oblique joins one sacroiliac articulation to the iliopubic eminence of the other side; the transverse diameter of the inlet joins the two most widely separated points of the pelvic inlet; and the transverse diameter of the outlet joins the medial surfaces of the ischial tuberosities.
pelvic inflammatory disease any pelvic infection involving the upper female genital tract beyond the cervix; such diseases are a major cause of female infertility.