The pelvic bone is irregular in shape and has two major parts separated by an oblique line on the medial surface of the bone (Fig. 5.19A):
The pelvic bone above this line represents the lateral wall of the false pelvis, which is part of the abdominal cavity.
The pelvic bone below this line represents the lateral wall of the true pelvis, which contains the pelvic cavity.
The linea terminalis is the lower two-thirds of this line and contributes to the margin of the pelvic inlet.