ilio

Ilio is a combining form used in medical terminology to denote relation to the ilium, the upper wing-like part of the hip bone. In anatomy, ilio- appears in compound terms that refer to structures and regions around the pelvis and the hip joint.

The ilium is one of the three fused bones of the pelvic girdle, alongside the ischium and pubis. It forms the superior portion of the acetabulum, the socket for the femoral head, and provides attachment for muscles via landmarks such as the iliac crest and the anterior superior iliac spine. The prefix ilio- is used in various anatomical terms to indicate a connection with the ilium, and it is derived from the Latin ilium.

Common ilio- terms include the iliofemoral ligament, which extends from the ilium to the femur and is a major stabilizer of the hip; the iliohypogastric nerve, a branch of the L1 spinal nerve that supplies portions of the abdominal wall; and the ilioinguinal nerve, also from L1, which supplies skin and soft tissue in the groin region. These terms illustrate how ilio- functions as a mnemonic in anatomy to situate structures in relation to the ilium and pelvis.

In medical literature, ilio- helps distinguish pelvic and hip structures from those related to other regions. It is related to, but distinct from, iliac- terms that describe broader aspects of the ilium, and from ilium itself, the bone. See also ilium, iliac crest.