Obturator internus

A muscle located in the pelvis, playing a key role in the movement of the hip joint.

The obturator internus is a small, triangular muscle situated in the pelvic cavity. It originates from the inner surface of the obturator membrane and the surrounding bony framework of the pelvis. The muscle passes through the lesser sciatic foramen and inserts onto the greater trochanter of the femur. Its position and shape allow it to assist in rotating the thigh outward (laterally) when the hip is extended.

Terminologia Anatomica

musculus obturatorius internus

System

Muscular system

Function

The primary function of the obturator internus is to facilitate the lateral rotation of the hip joint. This muscle works in conjunction with other muscles of the gluteal region and the rotator cuff of the hip, playing a vital role in movements such as walking, running, and any activities that require outward rotation of the thigh. In addition to rotation, the obturator internus contributes to stabilizing the hip joint, particularly during activities that involve weight bearing or changes in direction. As it contracts, it also helps to maintain pelvic stability by providing support to the pelvic floor, thus serving multiple important roles in locomotion and postural control.

Location

The obturator internus is located deep within the pelvis, specifically in the posterior pelvic wall. It is found below the gluteal region and above the obturator externus muscle. This placement allows it to connect the pelvic cavity to the femur through the lesser sciatic foramen, an important passageway in the pelvis. The obturator internus lies in close proximity to several other key muscles, such as the gluteus maximus and the quadratus femoris, which enhances its functional harmony with the surrounding musculature. Its unique positioning enables it to influence hip movement effectively while also contributing to the overall stability of the pelvic region.

Did You Know?

The obturator internus is one of the six deep external rotators of the hip, highlighting its important role in thigh rotation.
This muscle is often overlooked but is crucial for athletes engaged in sports requiring rapid directional changes.
Injury or dysfunction of the obturator internus can lead to pain and limitations in hip movement, often mimicking other conditions.
It shares innervation with other pelvic floor muscles, indicating its role in both musculoskeletal and pelvic function.