The ilium is the highest and largest of the three pelvic bones that make up the pelvic girdle. It is characterized by the ala, or wings, that flare out from the sides. It functions as part of the musculoskeletal system, helping to support the weight and posture of the body. The bone also serves as an anchor for muscles, tendons, and ligaments of the pelvic region and protects the internal organs.
The pelvic girdle is made up of three bones; the ilium, the ischium, and the pubis, which fuse together in a grown adult. The ilium, Latin for “groin” or “flank,” is the largest of these. The hipbones are part of the iliac crest. The bone supports the sacrum, which supports the spine.
The space between the outer edges of the upper iliac bones is called the biiliac width and is used by anthropologists and forensic specialists to estimate body mass. The measurement is also useful in obstetrics to make sure the baby has a big enough passage during delivery. The typical female biiliac measurement is 11 inches (28 cm).
Disorders of the illium are rare and typically caused by sports injuries or trauma. Iliolumbar Syndrome is an inflammation of the iliolumbar ligament that attaches to the ilium. This is usually a result of repeated bending or twisting, such as the kind seen in volleyball or golf. The syndrome affects the vertebrae attached to the pelvis and the surrounding area.
Symptoms can include pain in the lower back or groin area that can radiate down the buttock or leg, stiffness, and difficulty in movement. Treatment often utilizes alternating applications of heat and cold, anti-inflammatory medications, and physical therapy. In serious cases, a back brace may also be used.
Other disorders involving the bone include arthritis, low back pain, and sacroiliac joint dysfunction. More women than men suffer from these problems, and it is theorized that the cause is hormonal, because during pregnancy, a female’s body produces hormones to relax the ligaments to allow the pelvis to stretch. At this time, no studies have been done to verify this theory.
The ilium is a vital part of the body’s musculoskeletal support system, and its health is important to gait and posture. Recommendations for iliac health include stretching exercises to maintain the flexibility of the ligaments and strengthen the muscles supporting the ilium and surrounding vertebrae. Yoga and Pilates are just two types of exercises shown to be beneficial in preventing and managing injury to this area of the body.