Hip pain can be attributed to a number of causes in and around the hip joint and understanding the anatomy of the hip joint and it's associated bursae will help solve some less common causes of hip pain. 

Obturator internus bursa is one of the less commonly visualized bursa among the 20 odd bursae around the hip joint. It is typified by it's classical 'boomerang' appearance on axial images and appears on MRI only when it is inflamed.