CHAPTER I ANATOMY OF THE FEMALE PELVIS AND GENERATIVE ORGANS NORMAL FEMALE PELVIS The present broad knowledge of the anatomy of the female pelvis has resulted in an enormous reduction in death and injury among obstetrical patients and their babies. This knowledge of the pelvic anatomy, relating as it does, to both normal and malformed pelves, has made possible a system of taking measurements, termed _pelvimetry_, which gives the obstetrician a fair idea of the size and shape of his patient’s pelvis. Such information, coupled with observations upon the size of the child’s head, gives a foundation upon which to base some expectation of the ease or difficulty with which the approaching delivery is likely to be accomplished. Since each patient’s pelvic measurements are considered from the standpoint of their comparison with normal dimensions, it is manifestly important that the obstetrical nurse have a clear idea of the structure of the normal female pelvis, and also of its commonest variations. Viewed in its entirety, the pelvis is an irregularly constructed, two-storied, bony cavity, or canal, situated below and supporting the movable parts of the spinal column, and resting upon the femora or thigh bones. (Fig. 1, A. and B.). Four bones enter into the construction of the pelvis: the two hip bones or _ossa innominata_, on the sides and in front with the _sacrum_ and _coccyx_ behind. =The innominate bones= (ossa innominata), symmetrically placed on each side, are broad, flaring and scoop-shaped. Each bone consists of three main parts, which are separate bones in early life, but firmly welded together in adults: the _ilium_, _ischium_ and _pubis_. The ilia are the broad, thin, plate-like sections above, their upper, anterior prominences, which may be felt as the hips, are the _anterior superior spinous processes_ used in making pelvic measurements. The margins extending backward from these points are termed the _iliac crests_. The ischii are below and it is upon their projections, known as the _tuberosities_, that the body rests when in the sitting position, and which also serve as landmarks in pelvimetry. The pubes form the front of the pelvic wall, the anterior rami uniting in the median line by means of heavy cartilage and forming the _symphysis pubis_.