Obturator Internus Muscle (OI)

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

Overview

Muscle	Origin	Insertion	Innervation	Action
Obturator Internus	Obturator membrane and its bony boundaries	Medial surface of Greater Trochanter	Nerve to Obturator internus L5 - S1	Hip: ER, Extension, Abduction, Stabilization

Origin

Inner surface of the obturator membrane and its bony boundaries¹

Insertion

Medial surface of the greater trochanter¹

Innervation

Sacral plexus (L5, S1)¹

Action

• External rotation and extension of the hip joint (also active in abduction, depending on the joint’s position)¹
• Stabilizes hip joint -DrK

Function

“Ultrasound ­guided EMG analysis of the obturator internus and several other external rotator muscles in 10 human subjects.98 The obturator internus was usually the first muscle to become active during a gradually increasing isometric effort to abduct and externally rotate the hip.”²

Stretch

Child’s Pose stretch can be used to stretch the Obturator Internus muscle. By cueing the knees to stay straight instead of moving into hip ER, this better stretches the obturator internus.

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.