The Anatomy and Function of the Obturator Externus

Abstract

There is limited knowledge regarding the anatomic relationships and functional anatomy of the Obturator Externus muscle (OE). It is described as a muscle which originates from the external bony margin of the obturator foramen with a cylindrical tendon which passes like a sling under the femoral neck and inserts in the trochanteric fossa. The primary aim of this study is to describe the OE morphology and its anatomic relationship to the acetabulum. A secondary aim is to postulate its action. Eighteen fresh human cadaveric hips were dissected to investigate the anatomy of the OE. A plastic model of the pelvis and femur was used to create a string model based on a technique previously described by Beck et al. The plastic model was used to determine the function of the OE.We conclude that the Obturator externus muscle helps to stabilise the head of the femur in the socket. The mechanical model demonstrated that the primary action of the obturator externus muscle was to externally rotate the femur when the hip was in neutral position and flexed at 90°. Its secondary function was as an adductor when the hip was in flexion.

Characteristics of acute groin injuries in the adductor muscles: A detailed MRI study in athletes

“…For the present sub‐study focusing on MRI findings, only players with a positive MRI (defined as imaging findings indicating edema with or without structural disruption, as well as complete muscle disruptions or avulsions) in the adductor muscle group (adductor longus, adductor brevis, pectineus, adductor magnus, gracilis, and obturator externus) were included. The obturator externus was included based on its secondary function as a hip adductor, as well as being a known, although uncommon, cause of acute anterior hip or groin pain in sport . Ethical approval was obtained from the Shafallah Medical Genetics Center Institutional Review Board (IRB#: 2012‐013) and the Anti‐Doping Lab Qatar Institutional Review Board (IRB#: EXT 2014000004).…”

Acute Groin Pain Syndrome Due to Internal Obturator Muscle Injury in a Professional Football Player

“…These muscles are known under the collective name of "short lateral rotators." 12 This muscle group performs a major hip-joint stabilizing action, stabilizing the femoral head within the acetabulum during hip movements. 10 Despite the important work done by this muscle group, little is found in the literature.…”

Internal obturator muscle indirect injury in groin pain syndrome: a systematic review of the literature

“…Finally IO inserts at the medial surface of the great trochanter, in antero-posterior to the trochanteric pit. At the level of its distal insertion, the IO blends with the tendon of the gemelli muscles (triceps coxae) forming a common tendon 2,16,17 . This anatomical association with the gemelli tendon can explain the less frequent injuries of IO in comparison to EO 14 .…”

“…In addition to the IO, the other muscles working as hip external rotators are piriformis, external obturator, gemelli and quadratus femoris. These muscles are known under the collective name of "short lateral rotators" 16 . This muscle group performs a major hip-joint stabilizing action, stabilizing the femoral head within the acetabulum during hip movements 2,16 .…”