has part has part characteristic of has modifier Abnormal ischium morphology Narrow greater sciatic notch The sacroiliac joint in the bony pelvis connects the sacrum and the ilium of the pelvis, which are joined by strong ligaments. The notch is located directly superior to the joint. This term refers to a reduction in the lateral dimension of the notch. Abnormal greater sciatic notch morphology abnormal decreased width greater sciatic notch