obturator externus
noun
obturator ex·ter·nus
| \ -ek-ˈstər-nəs
\
\
Medical Definition of obturator externus
: a flat triangular muscle that arises especially from the medial side of the obturator foramen made up of the rami of the pubis and ischium and from the medial part of the obturator membrane, that inserts by a tendon into the trochanteric fossa of the femur, and that acts to rotate the thigh laterally