Pelvic outlet

The lower circumference of the lesser pelvis is very irregular; the space enclosed by it is named the inferior aperture or 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 tip 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.

See also

Pelvic inlet

Additional images

• 

  Articulations of pelvis. Anterior view.

• 

  Articulations of pelvis. Posterior view.

External links

• pelvis at The Anatomy Lesson by Wesley Norman (Georgetown University) (medialpelvissmall, malepelvissagittalinlet&outletsml)