Pubis

Key Features & Anatomical Relations

The pubis (pubic bone) is the smallest of the three bones that form the hip bone, the other two being the ilium and ischium. It’s a thick, irregularly shaped bone that is found along the anteroinferior aspect of the pelvic girdle. It is classified as an irregular bone and includes the following bony features:

- parts: body, superior pubic ramus and inferior pubic ramus;

- surfaces: anterior, posterior and symphyseal surfaces of body, and pectineal, obturator and pelvic surfaces of superior pubic ramus;

- landmarks: obturator groove and pubic tubercle.

More information regarding these bony features can be found in the Parts, Surfaces and Landmarks tabs for this bone.

The pubis is located:

- proximal to the femur;

- inferior to the ilium;

- medial to the ischium.

It articulates with the:

- ilium and ischium, via triradiate cartilage in childhood and fused joints in adulthood;

- femur at the hip joint;

- contralateral pubis at the pubic symphysis joint.

Ossification

Ossification of the pubis occurs at two ossification centers, these are found in the:

- superior pubic ramus, which appears in utero during the fourth to fifth months;

- body of pubis, which appears during early to middle adolescence.

These ossification centers fuse with each other during middle adolescence to early adulthood. Fusion between the body of ilium, body of ischium, and superior pubic ramus occurs at the acetabulum during middle to late adolescence, forming the fused hip bone. Fusion between the ramus of ischium and inferior pubic ramus occurs within the seventh to eighth years, forming the fused ischiopubic ramus (Standring, 2016).

Variations

The pubis displays sexual dimorphism, where:

- the ischiopubic ramus tends to be wider and more rugged in males;

- the pubic angle, formed by the inferior pubic rami of opposing pubic bones, is more acute in males than in females.

Surface Anatomy

The following bony features of the pubis are relevant to surface anatomy:

- the pubic symphysis can be located by deep palpation in the region that is immediately superior to the external genitalia;

- the pubic tubercle and pubic crest can be palpated by moving laterally from the pubic symphysis.

List of Clinical Correlates

- Fracture of superior pubic ramus

- Fracture of inferior pubic ramus

- Diastasis of pubic symphysis

References

Standring, S. (2016) Gray's Anatomy: The Anatomical Basis of Clinical Practice. Gray's Anatomy Series 41st edn.: Elsevier Limited.