Obturator externus
Obturator externus
- Latin synonym: Musculus obturatorius externus
- Synonym: Obturator externus muscle
Definition
Obturator externus | |
Origin | Outer aspect of the obturator membrane and surrounding bone of the obturator foramen. |
Insertion | trochanteric fossa and medial aspect of greater trochanter of femur |
Artery | Obturator artery |
Innervation | Posterior division of obturator nerve (L3, L4) |
Action | Rotate laterally thigh, assists in stabilizing the head of the femur within the acetabulum |
The obturator externus is a short, flat, triangular muscle situated deep in the medial aspect of the thigh. It forms part of the group of short external rotators of the hip.
Origin
The muscle fibres originate from the:
External (outer) surface of the obturator membrane
The bony margins of the obturator foramen, namely the superior and inferior rami of the pubis and the ischial ramus
The tendinous arch completing the obturator canal (through which the obturator vessels and nerves pass)
Insertion
The muscle fibres of the obturator externus converge laterally and posteriorly to form a tendon. This tendon of the obturator externus passes posterior to the neck of the femur and beneath the capsule of the hip joint, to be inserted into the trochanteric fossa of the femur (on the medial aspect of the greater trochanter).
Action
Primary action: External (lateral) rotation of the thigh at the hip joint
Accessory action: Stabilization of the head of the femur within the acetabulum.
References
Larson MR, Ryan W. Anatomy, Abdomen and Pelvis, Obturator Muscles. [Updated 2023 Jan 17]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK589636/
