The ischium is one of the three main bones that make up the pelvis, which is the structure that supports the spine and connects to the legs. It is located at the lower part of the pelvis and forms the back portion of the hip bone. The ischium plays a crucial role in bearing weight when sitting and provides attachment points for various muscles and ligaments. In addition to its structural importance, the ischium is also involved in the formation of the acetabulum, the socket that holds the femur (thigh bone) to create the hip joint. This connection allows for a wide range of movement in the legs, making activities like walking and running possible.