Outlet_of_the

Outlet of the pelvis

Bone: Pelvic outlet

Diameters of inferior aperture of lesser pelvis (female).

Muscles of the female perineum.

Latin apertura pelvis inferior

Gray's subject #58 240

Dorlands
/ Elsevier a_51/12144712

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:

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.

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

Articulations of pelvis. Anterior view.

Articulations of pelvis. Posterior view.

v • d • e Bones of pelvis / pelvic cavity

General	sacrum, coccyx, hip bone

Ilium	body (arcuate line) wing: gluteal lines (posterior, anterior, inferior) – fossa – iliac spines (anterior superior, anterior inferior, posterior superior, posterior inferior) – crest – tuberosity

Ischium	body (ischial spine, lesser sciatic notch) – superior ramus (tuberosity of the ischium) – inferior ramus

Pubis	body – superior ramus (pubic tubercle, pubic crest, obturator crest) – inferior ramus (pectineal line)

Compound	acetabulum (acetabular notch) – iliopubic eminence / iliopectineal line – linea terminalis – ischiopubic ramus / pubic arch obturator foramen – greater sciatic foramen / greater sciatic notch – lesser sciatic foramen lesser pelvis (pelvic inlet, pelvic brim, pelvic outlet) – greater pelvis