The inferior pubic ramus is thin and flattened. It passes lateralward and downward from the medial end of the superior ramus; it becomes narrower as it descends and joins with the inferior ramus of the ischium below the obturator foramen.
Its anterior surface is rough, for the origin of muscles—the Gracilis along its medial border, a portion of the Obturator externus where it enters into the formation of the obturator foramen, and between these two, the Adductores brevis and magnus, the former being the more medial.
The posterior surface is smooth, and gives origin to the Obturator internus, and, close to the medial margin, to the Constrictor urethræ.
The medial border is thick, rough, and everted, especially in females. It presents two ridges, separated by an intervening space. The ridges extend downward, and are continuous with similar ridges on the inferior ramus of the ischium; to the external is attached the fascia of Colles, and to the internal the inferior fascia of the urogenital diaphragm.
The lateral border is thin and sharp, forms part of the circumference of the obturator foramen, and gives attachment to the obturator membrane.