Where is the ilium? Location, iliac crest, ASIS and muscles of the upper hip bone
Where is the ilium?
Put your hands on your hips, about where a belt sits. The hard edge under your fingers is the top of the ilium, called the iliac crest.
There is one ilium on each side. Together they hold the sacrum between them at the back of the pelvis, and from the front they flare out like a shallow bowl under the abdominal organs.
Ilium, ischium and pubis
Each hip bone (os coxae) starts as three bones: the ilium above, the ischium behind and below, and the pubis in front. They fuse in the late teens at the acetabulum, the socket for the head of the femur. In an adult skeleton the borders are no longer visible.
Parts and landmarks
・Iliac crest: the upper edge. A line joining the highest points of both crests passes roughly through the fourth lumbar vertebra
・Anterior superior iliac spine (ASIS): the front end of the crest, felt just below the belt line
・Anterior inferior iliac spine (AIIS): just below the ASIS, covered by muscle
・Posterior superior iliac spine (PSIS): the back end of the crest, under the dimples some people have above the buttocks
・Iliac fossa: the shallow hollow on the inner surface
・Auricular surface: the ear-shaped surface that joins the sacrum at the sacroiliac joint
Muscles attached to the ilium
The iliacus arises from the iliac fossa and joins the psoas major to form the iliopsoas. The gluteus maximus, medius and minimus arise from the outer surface. The sartorius starts at the ASIS, the rectus femoris at the AIIS, and the abdominal muscles and latissimus dorsi attach along the iliac crest.
See it in 3D
Textbook figures usually show the pelvis from the front or the side only. In the teamLabBody 3D anatomy app you can rotate and zoom the pelvis to see the ilium from any angle, and PREMIUM cross-sections show how the ilium and sacrum sit together.
FAQ
- Where can I feel my ilium?
- Place your hands on your hips at belt level. The bony edge is the iliac crest. Follow it forward to the ASIS at the front, or backward to the PSIS near the dimples above the buttocks.
- What is the difference between the ilium, ischium and pubis?
- All three are parts of the hip bone. The ilium is the large upper part, the ischium is the lower back part you sit on, and the pubis is the lower front part where the two sides meet. They fuse at the acetabulum in the late teens.
