Pelvic outlet

Boundaries

It has the following boundaries:

• anteriorly: the pubic arch
• laterally: the ischial tuberosities
• posterolaterally: the inferior margin of the sacrotuberous ligament
• posteriorly: the anterior border of the middle of the coccyx.

Notches

These eminences are separated by three notches:

• one in front, the pubic arch, formed by the convergence of the inferior rami of the ischium and pubis on either side.
• The other notches, one on either side, are formed by the sacrum and coccyx behind, the ischium in front, and the ilium above; they are called the sciatic notches; in the natural state they are converted into foramina by the sacrotuberous and sacrospinous ligaments.

In situ

When the ligaments are in situ, the inferior aperture of the pelvis is lozenge-shaped, bounded as follows:

• in front, by the pubic arcuate ligament and the inferior rami of the pubes and ischia
• laterally, by the ischial tuberosities
• behind, by the sacrotuberous ligaments and the tip of the coccyx.

Additional images

File:Gray319.png|Articulations of pelvis. Anterior view. File:Gray320.png|Articulations of pelvis. Posterior view. File:Low-dose CT of sagittal pelvic outlet diameter.jpg|Low-dose CT scan of sagittal pelvic outlet diameter as part of pelvimetry File:Low-dose CT scan of intertuberous diameter.jpg|Intertuberous diameter, as a measure of the transverse measure of the pelvic outlet

References

References

1. Sara Paterson-Brown, Phillip Bennett, Catherine Williamson. (2010). "Basic Science in Obstetrics and Gynaecology (Fourth Edition) - Obstetric pelvic definitions and dimensions". Elsevier Ltd.