The pelvis is the part of the body located between the abdomen and the thighs. The term `pelvis` can refer to the pelvic skeleton (also known as the pelvic girdle), which is the skeleton embedded in the lower part of the trunk, connecting the axial skeleton to the lower extremities.
There are four joints within the pelvis:
- sacroiliac joints (2) - articulations between the ilium of the hip bones, and the sacrum;
- sacrococcygeal symphysis - between the sacrum and the coccyx;
- pubic symphysis - between both bodies of the pubis in the anterior midline.
Several ligaments extend between the lateral borders of the sacrum to various bony landmarks on the pelvis, aiding stability to the pelvis.
The pelvic skeleton is strong and rigid, adapted to serve several roles in the human body, including:
- transferring weight from the upper axial skeleton to the lower extremities, especially during motion;
- providing attachment for many muscles and ligaments used in locomotion;
- enclosing and protecting abdominopelvic and pelvic viscera.
Greater and lesser pelvis
The greater pelvis is the space between the two wings of the ilium above the terminal line, while the lesser pelvis is the part of the pelvis below the terminal line. The greater pelvis is also known as the false pelvis. It provides support for the lower abdominal viscera and has little obstetric relevance. The lesser pelvis, on the other hand, is also called the true pelvis. It contains the pelvic cavity and the pelvic viscera within it. The junction between the greater and lesser pelvis is known as the pelvic inlet.