ischia

In anatomy, the ischia are the two corresponding lower-back portions of the hip bones. Together with the pubis and the ilium, the ischium forms each side of the pelvis. These sturdy structures support the upper body when a person sits and provide attachment points for muscles and ligaments, including the hamstring muscles. The English plural is irregular in the sense that its singular is ischium, but the plural is formed regularly with the ending -a: one ischium and two ischia. Although the word can occur in general descriptions of the skeleton, it is most familiar in medical, anatomical, and physiotherapy contexts. It should not be confused with ischial, an adjective meaning “relating to the ischium,” or with ischias, a painful inflammation of the sciatic nerve.

The plural of ischium: either of the two posteroinferior portions of the hip bones, which form the lower back part of the pelvis and bear weight when sitting.

Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.

Where does ischia come from?

The singular ischium comes from Latin ischium, which was borrowed from the Greek ischion, meaning “hip” or “hip bone.” The English plural ischia follows the usual Latin -a plural pattern. Related English forms include the adjective ischial and the words sciatic and sciatica, which ultimately derive from the same Greek root for the hip.

Related word forms

How ischia is actually used

This is primarily medical and anatomical vocabulary. In English, it occurs as the plural of ischium; the singular ischium is used for the corresponding portion of the hip bone.

Words and phrases paired with ischia