Obturator Externus

Origin, Insertion, Action, Innervation

Origin: External surface of the obturator membrane and the surrounding bony margins of the obturator foramen (pubis and ischium)
Insertion: Trochanteric fossa of the femur (medial surface of the greater trochanter, posterior to the femoral neck)
Action:
Primary: External (lateral) rotation of the hip
Stabilization of the femoral head in the acetabulum (the muscle wraps around the posterior femoral neck, pulling the head into the socket)
Slight adduction of the hip
Innervation: Posterior branch of the obturator nerve (L3, L4)

Client position: Supine with the hip flexed, abducted, and externally rotated (similar to a figure-4 position). This position exposes the medial thigh and relaxes the overlying adductors.
Landmark sequence:

Locate the adductor group on the medial thigh. The obturator externus lies deep to the adductors, against the obturator membrane on the external surface of the pelvis.
From the medial thigh with the hip in the figure-4 position, palpate deeply posterior to pectineus and adductor brevis, aiming toward the obturator foramen.
In practice, obturator externus is extremely difficult to palpate directly due to the depth of overlying tissue. Most clinicians treat it as part of the deep rotator group from the posterior approach (sidelying) rather than attempting direct medial palpation.

Tissue feel: If accessible, feels like a deep, firm layer against the obturator membrane. In practice, individual identification by tissue feel is unreliable.
Confirmation test: No reliable isolated palpation confirmation. Resisted external rotation activates all six deep rotators simultaneously.
Common errors:
Attempting to isolate it from the medial approach — the overlying adductors, pectineus, and neurovascular structures make direct access impractical in most clients. Treat it as part of the deep rotator complex from the posterior-lateral approach.
Confusing with adductors — if the tissue contracts with hip adduction rather than external rotation, you are on the adductor group.

Common TrP locations: In the muscle belly near the obturator foramen, deep to the adductor group on the medial proximal thigh.
Referral pattern: Deep groin pain and medial thigh aching. May refer to the anterior hip joint region.
Clinical significance: Obturator externus TrP referral to the groin mimics adductor strain, hip joint pathology, or obturator nerve entrapment. In clients with persistent deep groin pain and negative adductor tests, consider the deep rotators — obturator externus is the most anterior of the group and the most likely to produce groin-pattern pain.

Trigger point referral diagram — coming soon

Image coming soon. For visual reference, see [Obturator Externus at TriggerPoints.net](http://www.triggerpoints.net/muscle/obturator-externus).

Common conditions:

Relevant to conditions/hip-osteoarthritis — as a deep stabilizer of the femoral head, obturator externus hypertonicity is a compensatory response to hip joint instability or degenerative change. The muscle tightens to protect the joint, limiting range of motion, particularly internal rotation.
Part of the deep rotator complex relevant to conditions/piriformis-syndrome — while piriformis is the most commonly blamed, all six deep rotators can contribute to sciatic nerve region compression.
Obturator nerve entrapment — because the obturator nerve innervates this muscle and passes through the obturator foramen, pathology here can involve the nerve, producing medial thigh pain and adductor weakness.

What you'll typically find:

Obturator externus is rarely symptomatic in isolation. When the deep six are involved, it contributes as part of the group. The primary clinical value of knowing this muscle is understanding the deep rotator complex as a whole.
In clients with hip OA, all the deep rotators — including obturator externus — guard the joint by maintaining external rotation tension. The loss of internal rotation in hip OA is partly capsular and partly muscular from deep rotator guarding.
Because of its unique innervation (obturator nerve rather than sacral plexus), obturator externus involvement can produce a different symptom pattern (groin and medial thigh) than the other five deep six muscles (buttock and posterior thigh).

Treatment effects:

Treated indirectly through the posterior deep rotator approach — sustained compression and stripping through the deep six from the sidelying position affects obturator externus as part of the group.
Direct treatment from the medial thigh is possible but requires careful navigation around the femoral neurovascular bundle (femoral artery, vein, and nerve in the femoral triangle). This approach is advanced and not routine in most clinical settings.

Cautions:

The obturator neurovascular bundle passes through the obturator foramen alongside this muscle. Deep medial palpation near the obturator foramen risks compressing these structures.
The femoral artery, vein, and nerve lie superficial to the approach from the medial thigh. Avoid deep sustained pressure in the femoral triangle (bounded by the inguinal ligament, sartorius, and adductor longus).

Clinical pearl:

Obturator externus is unique among the deep six because it wraps around the posterior femoral neck from the front. This means it stabilizes the hip joint from a completely different angle than the other five rotators (which all approach from behind). In hip OA, releasing the posterior deep five without addressing obturator externus may leave residual external rotation limitation that the posterior approach alone cannot resolve.

Resisted external rotation (shared with all deep six):

Client supine with hip and knee flexed to 90 degrees. Resist external rotation at the ankle. This tests the deep rotator group collectively — obturator externus cannot be isolated clinically.

Passive hip internal rotation (hip flexed to 90 degrees):

Client supine with the hip and knee flexed to 90 degrees. Passively internally rotate the hip. Restriction with deep groin or anterior hip pain (rather than posterior buttock pain) may implicate the anterior deep rotators, including obturator externus.

Deep six hip external rotators (anatomical):

Obturator nerve group (innervation):

Deep six rotators:

anatomy/muscles/obturator-internus — internal surface counterpart; exits through the lesser sciatic notch
anatomy/muscles/piriformis — most superior and clinically prominent of the deep six
anatomy/muscles/quadratus-femoris — most inferior of the deep six

Antagonists (hip internal rotation):

The deepest and least accessible of the deep six — treat as part of the rotator group rather than as an isolated target.
Unique obturator nerve innervation produces groin and medial thigh referral, unlike the posterior buttock pattern of the other five deep rotators.
Wraps around the posterior femoral neck from the front — contributes to external rotation restriction in hip OA from a different angle than the posterior rotators.