We are independent & ad-supported. We may earn a commission for purchases made through our links.
Advertiser Disclosure
Our website is an independent, advertising-supported platform. We provide our content free of charge to our readers, and to keep it that way, we rely on revenue generated through advertisements and affiliate partnerships. This means that when you click on certain links on our site and make a purchase, we may earn a commission. Learn more.
How We Make Money
We sustain our operations through affiliate commissions and advertising. If you click on an affiliate link and make a purchase, we may receive a commission from the merchant at no additional cost to you. We also display advertisements on our website, which help generate revenue to support our work and keep our content free for readers. Our editorial team operates independently of our advertising and affiliate partnerships to ensure that our content remains unbiased and focused on providing you with the best information and recommendations based on thorough research and honest evaluations. To remain transparent, we’ve provided a list of our current affiliate partners here.

What is the Iliolumbar Ligament?

By Shelby Miller
Updated May 17, 2024
Our promise to you
WiseGeek is dedicated to creating trustworthy, high-quality content that always prioritizes transparency, integrity, and inclusivity above all else. Our ensure that our content creation and review process includes rigorous fact-checking, evidence-based, and continual updates to ensure accuracy and reliability.

Our Promise to you

Founded in 2002, our company has been a trusted resource for readers seeking informative and engaging content. Our dedication to quality remains unwavering—and will never change. We follow a strict editorial policy, ensuring that our content is authored by highly qualified professionals and edited by subject matter experts. This guarantees that everything we publish is objective, accurate, and trustworthy.

Over the years, we've refined our approach to cover a wide range of topics, providing readers with reliable and practical advice to enhance their knowledge and skills. That's why millions of readers turn to us each year. Join us in celebrating the joy of learning, guided by standards you can trust.

Editorial Standards

At WiseGeek, we are committed to creating content that you can trust. Our editorial process is designed to ensure that every piece of content we publish is accurate, reliable, and informative.

Our team of experienced writers and editors follows a strict set of guidelines to ensure the highest quality content. We conduct thorough research, fact-check all information, and rely on credible sources to back up our claims. Our content is reviewed by subject-matter experts to ensure accuracy and clarity.

We believe in transparency and maintain editorial independence from our advertisers. Our team does not receive direct compensation from advertisers, allowing us to create unbiased content that prioritizes your interests.

The iliolumbar ligament is a tough, dense band of fibrous tissue made up of bundles of collagen fibers connecting the spine to the pelvis. It is one of several ligaments in the region linking the lumbar vertebrae to the hipbone and to the adjacent sacrum. Like any ligament, its job is to connect bone to bone and maintain stability in the surrounding structures.

One on end, the iliolumbar ligament attaches to the transverse process of the fifth lumbar vertebra. The transverse process is a pointed, narrow bony protrusion emanating, wing-like, from each side of the vertebra. From there it runs horizontally across the gap between the spine and the ilium, the large, butterfly-shaped hipbone, and attaches on its other end to the iliac crest. The iliac crest is the topmost edge of the “wing” of the ilium, easily felt at the tops of the hips on either side. Specifically, the iliolumbar ligament connects to the inside lip of the iliac crest at its most posterior point, to either side of the tailbone.

Representing a border between the back and the hips, the iliolumbar ligament forms the bottom edge of the thoracolumbar fascia. The thoracolumbar fascia is a large membrane layered between and above the muscles of the low back, visible in anatomy drawings as an area of gray fibrous tissue separating the back muscles from the hipbones. It attaches medially along the thoracic and lumbar vertebrae, laterally to the transversus abdominis muscle on the sides of the trunk, and along its lower border to the iliac crest, ending at the iliolumbar ligament.

This ligament features two separate bands, with the upper band forming the border of the fascia and attaching to the iliac crest just anterior to or in front of the sacroiliac (SI) joint. The lower band stretches beneath it from the crest to the base of the sacrum, the stacked fused vertebral bone just below the lumbar spine, where it converges with the anterior sacroiliac ligament. This broad, short ligament horizontally connects the medial or inside edge of the ilium to the sacrum.

Several muscles come into contact with the iliolumbar ligament as they cross from the trunk of the body to the pelvis. The psoas major, the largest of the hip flexor muscles, descends from its origin along the thoracic and lumbar vertebrae and passes the anterior side of the ilium just in front of the ligament, inserting on the femur bone below. To the rear of the iliolumbar ligament are the erector spinae muscles, which run vertically along a groove to either side of the vertebral column and attach at various points along the sacrum. Finally, this ligament is bordered above and slightly laterally, or to the outside, by the quadratus lumborum muscle deep in the trunk, and spans the space between the iliac crest and the rib cage.

WiseGeek is dedicated to providing accurate and trustworthy information. We carefully select reputable sources and employ a rigorous fact-checking process to maintain the highest standards. To learn more about our commitment to accuracy, read our editorial process.
Discussion Comments
WiseGeek, in your inbox

Our latest articles, guides, and more, delivered daily.

WiseGeek, in your inbox

Our latest articles, guides, and more, delivered daily.