What does ischium mean?
The ischium is the posterior and inferior portion of the hip bone, one of the three components that form the pelvis. In the adult skeleton, it is fused with the ilium and pubis, forming a single continuous bone on each side of the pelvis. The ischium has a large projection, the ischial tuberosity, which bears much of the body's weight when a person sits. It also contributes to the margins of the obturator foramen and gives rise to structures associated with the hip and thigh. Although the word may sound unfamiliar, many related medical terms are familiar: “ischial” describes structures connected with this part of the hip bone, while “sciatic” and “sciatica” come from the same Greek root for the hip or hip joint. The ischium is consequently important not only in anatomical description but also in understanding the terminology used for pelvic and lower-back conditions.
nounThe ischium is the posterior and inferior part of the hip bone. In adults, it is fused with the ilium and pubis and forms part of the pelvis.
- The posterior and inferior part of the hip bone, forming part of the pelvis and bearing weight when seated.
"The ischium bears much of the body's weight when a person is seated."
"The ischium is one of the three bones that make up each side of the adult hip."
"Pressure on the ischial tuberosity can become painful during long periods of sitting."
The plural is chiefly used in anatomical and medical writing.
"The two ischia are connected at the front by the pubic bones."
Your seat has a bone to it: the ischium.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does ischium come from?
The word comes through New Latin from Greek ischion, meaning “hip” or “hip joint.” Ancient Greek writers used the term broadly for the hip region, including the socket or joint that receives the thigh bone. Latin formed related medical terms such as ischiaticus, the source of “sciatic” and “sciatica,” and English later developed “ischial” for structures belonging to the ischium.
Related word forms
How ischium is actually used
This is a technical anatomical term, used chiefly in medicine, anatomy, and related fields. Its plural is uncommon in general writing.
Easily confused with ischium
The ilium is the broad upper portion of the hip bone, whereas the ischium is its posterior and inferior portion.