Introduction[edit | edit source]
- The ilium, alongside the ischium and pubis are individual bones in the immature skeleton which fuse to form one bone in adults, the principal union being in the acetabulum.
- Via the sacroiliac ligaments, the ilium are attached to the sacrum. This juncture, which is largely immobile, is the sacroiliac joint.
As such, the ilium serves a weight-bearing function and is part of the structure that ensures the spine is supported when the body is upright. It’s therefore essential as part of the apparatus that allows for locomotion.
Gross Anatomy[edit | edit source]
The ilium consists of a flared expanded upper part forming the iliac crests, the iliac spines, and a small inferior part forming two-fifths of the acetabulum.
It has four borders - superior, anterior, posterior and medial borders; and three surfaces - gluteal, iliac fossa and sacropelvic.
Important Landmarks[edit | edit source]
The ilium also has a number of important landmarks, including:
- The iliac crest: the curved, upper margin of the ilium.
- The anterior superior spine: a bony projection marking the limit of the iliac crest on the front.
- The anterior inferior spine: a bony projection running beneath the anterior superior spine on the front side of the bone.
- The posterior superior spine: the terminus of the iliac crest on the rear-facing side of the ilium.
- The posterior inferior spine: below the posterior superior spine, and at the end of a larger, roughened region called the auricular surface.
- The iliac fossa is a shallow depression on the internal surface of the upper part of the bone.
- The greater sciatic arch is the larger U-shaped indentation at the rear margin of the lower ilium.
Attachments[edit | edit source]
Muscles that originate from ilium:
- sartorius muscle at the anterior superior iliac spine
- rectus femoris muscle from the anterior inferior iliac spine, the reflected head of this muscle originates from the supra-acetabular region of ilium
- gluteus maximus, medius and minimus muscles from the gluteal surface divided by bony impression or lines, the posterior, anterior and inferior gluteal lines
- iliacus muscle originates from upper two-thirds of the iliac fossa
- tensor fascia lata origins from the anterior and dorsal aspect of the iliac crest
Muscles that insert onto the ilium:
- quadratus lumborum muscle at the iliac crest and onto the iliolumbar ligament
- external oblique, internal oblique and transversus abdominis muscles of the abdominal musculature as well as latissimus dorsi muscle insert at the iliac crest
- inguinal ligament: anterior superior iliac spine
- iliofemoral ligament: anterior inferior iliac spine
- sacrotuberous ligament: posterior inferior iliac spine
- posterior sacroiliac ligament: iliac tuberosity
- interosseous sacroiliac ligament and ventral sacroiliac ligament: just posteroinferior and ventral to the auricular surface of iliac tuberosity
- iliolumbar ligament: anterior aspect of iliac tuberosity
Associated Conditions[edit | edit source]
The ilium can be the site of problems that affect the pelvis, eg
- The ilium can become fractured due to falls or other trauma. Symptoms of this include sharp pain, swelling and bruising, as well as an inability to put weight on the hip.
- Genetic deformities can also arise in the shape of the ilium and pelvis, which can also lead to a range of problems.
- Sacroiliitis, can lead to pain symptoms as well as fever and stiffness. This often arises due to arthritis in the hip.
References[edit | edit source]
- Very Well Health Ilium Available: https://www.verywellhealth.com/ilium-anatomy-4768496(accessed 5.11.2021)
- R%adiopedia Ilium Available: https://radiopaedia.org/articles/ilium?lang=gb(accessed 5.11.2021)