Obturator internus tendon !
The obturator internus tendon bends sharply around the hip bone as it leaves the pelvis and attaches to the greater trochanter.
Official name: Tendon of obturator internus
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What it is
The tendon of the obturator internus. It turns a sharp corner around the hip bone (the lesser sciatic notch) and joins the two gemelli to attach to the greater trochanter.
What it does
Carries the pull of the obturator internus and gemelli to turn the thigh outward.
Key facts
- Attaches
- Leaves the pelvis through the lesser sciatic foramen, turning about 90° over the lesser sciatic notch on a bursa; joined by the superior and inferior gemelli to the medial surface of the greater trochanter
- Function
- Lateral rotation of the extended hip and abduction of the flexed hip; holds the femoral head in the acetabulum
- Tight in
- Hip medial rotation
Relations
- Superficial
- Sciatic nerve and gluteus maximus
- Above
- Superior gemellus, then the piriformis
- Below
- Inferior gemellus, then the quadratus femoris
- Deep
- Back of the hip capsule and the ischium
- Medial
- Pudendal nerve and internal pudendal vessels in the lesser sciatic foramen
How to find it
Not palpable; in the posterior approach it is found between the two gemelli, below the piriformis, as a flat shiny tendon; ultrasound shows it curving round the ischium.
On imaging
On axial MRI it is seen bending round the lesser sciatic notch; fluid in its bursa there is an occasional finding, and oedema of the muscle can accompany deep buttock pain.
Common problems
- Uncommonly, a source of deep buttock or pelvic pain when strained or tight.
Clinical notes
- The obturator internus and gemelli can trap the sciatic nerve in deep gluteal syndrome
- Posterior hip dislocations often tear the short external rotators
- The pudendal (Alcock) canal is a sleeve in the fascia covering the obturator internus on the side wall of the ischioanal fossa; pudendal nerve entrapment there gives perineal pain that worsens on sitting
Anatomical variants
- Its tendon joins the piriformis tendon before inserting in about 1 in 10
Test yourself
Think of the answer, then tap the question to see it.
Through which foramen does the obturator internus tendon leave the pelvis?
The lesser sciatic foramen, turning about 90° over the lesser sciatic notch on a bursa.
Where does the obturator internus tendon insert?
With the superior and inferior gemelli, on the medial surface of the greater trochanter.
How does the obturator internus tendon help protect the sciatic nerve in the posterior hip approach?
It is detached and folded back over the sciatic nerve to shield it.
Educational information, not medical advice. For any symptom, see a health professional.
Its names
- Official Latin (TA2)
- obturator internus TA2 2605
- Official Spanish (DeCS)
- Tendón del obturador interno DeCS D013710
- English (TA2)
- Tendon of obturator internus
- Also called
- obturator internus muscle
Related
Sources: Terminologia Anatomica (TA2); DeCS; Anatomy, Abdomen and Pelvis, Obturator Muscles.
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Representative model, for educational purposes only.
