Pelvic Ligaments – Functional Anatomy

Overview

These pelvic ligaments bind the ox coxae of the lower extremity to the axial skeleton. They consist of:

• iliolumbar ligament
• sacroiliac ligament
• sacrotuberous ligament
• sacrospinous ligament

Progression of Fusion

A complex fascial structure wraps the major bony structures of the pelvis. Like those osseous structures, the ligaments also evolve as we age. As a result, we have more boney pieces held together by cartilaginous plates that fuse as decades pass in the first two or three decades. Eventually, in our fifth decade, pelvic joints, including the sacroiliac joint, often into one large pelvic structure. These ligaments also morph as the bones fuse.

It is larger in females than males.

In most illustrations, for clarity, they are shown as very separate structures. However, in reality, they appear more like thickened sections woven together into a larger whole.

Sacroiliac Joint

Before looking at pelvic ligaments, review the complexities of the sacroiliac joint. It varies with gender, age, and race like several of the pelvic ligaments.

Sacroiliac Ligament

The most complex of the pelvic ligaments. The anterior, posterior, and interosseous sections all perform different functions. Also, each section has a notably different structure.

Iliolumbar Ligament

This ligament is unique to animals that support their weight on their caudal limbs. It varies by gender, race, and age. It is worth noting how those factors may impact your approach.

Sacrotuberous Ligament

The sacrotuberous ligament is attached broadly to the lateral aspect of the sacrum from the PSIS to the coccyx. The fibers converge and extend posteriorly to the ischial tuberosity. Fibers of this ligament pass over the ischial tuberosity to become the origin tendon of the biceps femoris.

Sacrospinous Ligament

The sacrospinous ligament (small or anterior sacrosciatic ligament) is a thin, triangular ligament attached by its apex to the ischial spine and medially, by its broad base, to the lateral margins of the sacrum and coccyx, as it fuses with the sacrotuberous ligament. Its main function is to prevent posterior rotation of the ilium with relation to the sacrum. However, the laxity of this ligament, along with the sacrotuberous ligament, allows posterior rotation to occur.

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