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Obturatorius externus



  • Deep


  • Obturator membrane
    • External surface
  • Obturator foramen at os ischii and pubis
    • External surface


  • Trochanter fossa femur

Main function

  • Hip
    • Lateral rotation

Secondary function

  • Pelvis
    • Contralateral rotation

Nerve innervation

  • Segmental
    • L3-L4
  • Peripheral
    • Obturator nerve

Arterial supply

  • Obturator artery


  • Patient position
    • Prone
  • The obturator externus is deep and is difficult to palpate
    • You can palpate the deep lateral rotator group of the hip which the obturator externus is a part of, but it is difficult to isolate the muscle by itself
  • Place your hand just lateral to the sacrum, halfway between the SIPS and apex of sacrum
  • Ask the patient to flex the knee to 90°
  • Give resistance to the patient in the direction of medial rotation, so that the patient is giving force towards lateral rotation
    • Feel for the contraction while the movement is being performed
  • Note! The deep lateral rotator group of the hip also consists of quadratus femoris, obturator internus, piriformis, gemellus superior and gemellus inferior. It can be difficult to seperate between these muscles, and be aware that all of these will also be active during the movement
  • Also note that gluteus maximus can be activated during this movement
    • If you give too much pressure , so that the patient is giving more force into their resistance, this too will become active

Strength test

  • Patient position
    • Sitting with the knee in 90° flexion and the leg hanging freely over the ground
  • Place your one hand just laterally on the patient's thigh on the side which is to be tested
  • Use the opposite hand to give resistance to the patient
    • Place your hand along the medial side of the calf and pull the leg into a internal rotated position of the hip, so that the patient is giving resistance towards external rotation
  • Note that this test is also testing the quadratus femoris, obturator internus, obturator externus, gemellus superior and gemellus inferior which are all lateral rotators of the hip