Ischium

A key component of the pelvis that provides structural support and serves as a site for muscle attachment.

The ischium is one of the three bones that make up each half of the pelvis, along with the ilium and pubis. It is located at the lower and back part of the pelvis, forming the lower portion of the hip bone. The ischium is notable for its thick, curved shape and helps shape the contour of the pelvic cavity. This bone supports the body's weight when sitting and provides attachment points for various muscles and ligaments.

Terminologia Anatomica

ischium

System

Skeletal system

Function

The ischium plays several essential roles in maintaining overall body functionality. Firstly, it contributes to the structural integrity of the pelvis, providing a solid foundation for the upper body when seated. This support is crucial in various activities, including walking, running, and standing. Additionally, the ischium serves as an attachment point for multiple muscles, particularly those involved in the movement of the hip and thigh, such as the hamstring muscles. These muscles facilitate movements such as running and jumping. Furthermore, the ischium forms part of the ischial tuberosity, commonly referred to as the 'sit bones,' which provide stability during sitting and aid in weight distribution across the pelvis.

Location

The ischium is located in the lower region of the pelvis, inferior to the ilium and posterior to the pubis. It consists of a body and a ramus, which articulate with the other pelvic bones, forming the acetabulum—where the thigh bone (femur) fits into the hip joint. The ischial tuberosity extends posteriorly, providing a bony prominence that can be palpated in the seated position. This strategic positioning within the pelvic structure allows the ischium to bear weight effectively and contribute to the overall stability of the bipedal posture.

Did You Know?

The term 'ischium' is derived from the Greek word 'ischion,' meaning hip or thigh.
In some animals, the ischium is more elongated, adapting to their specific locomotion patterns.
Chronic sitting can lead to discomfort in the ischial tuberosities, emphasizing their importance for weight-bearing.