Obturator Externus

Authors

Affiliations

Nathaniel Yomogida, B.S., SPT

Doctor of Physical Therapy

B.S. in Kinesiology

Chloë Kerstein, B.S., SPT

Doctor of Physical Therapy

B.A. in Neuroscience

Medial Thigh muscle deep layer schematic
1: Obturator Externus
2: Adductor Magnus

Medial Thigh muscle deep layer¹

Muscle	Origin	Insertion	Innervation	Action
Obturator externus	Outer surface of Obturator membrane Adjacent bony boundaries	Trochanteric Fossa	Obturator n. L3 - L4	Hip: Adduction, ER Pelvis: Sagittal Stabilization

Origin

Outer surface of the obturator membrane and its bony boundaries¹

Insertion

Trochanteric fossa of the femur¹

Innervation

Obturator N. (L3, L4)¹

Action

• Hip: adduction and external rotation¹
• Pelvic Stabilization: Sagittal plane¹

Overview

“The obturator externus muscle arises from the external side of the obturator membrane and adjacent ilium (see Fig. 12.14). The belly of this muscle is visible from the anterior side of the pelvis after removal of the adductor longus and pectineus muscles (see Fig. 12.26, left side). The muscle attaches posteriorly on the femur at the trochanteric fossa (see Fig. 12.6). (Based on its leverage to produce adduction, location, and innervation, the obturator externus is more anatomically associated with the adductor group of muscles than with the other five short external rotators. The obturator externus is innervated by nerve roots that originate from the lumbar plexus [via the obturator nerve], as are most of the other adductor muscles. The other small external rotators, in contrast, are innervated through the sacral plexus, with nerve roots as low as S2.)”²

References

1.

Gilroy AM, MacPherson BR, Wikenheiser JC, Voll MM, Wesker K, Schünke M, eds. Atlas of Anatomy. 4th ed. Thieme; 2020.

2.

Neumann DA, Kelly ER, Kiefer CL, Martens K, Grosz CM. Kinesiology of the Musculoskeletal System: Foundations for Rehabilitation. 3rd ed. Elsevier; 2017.