Quadratus Femoris

Origin, Insertion, Action, Innervation

Origin: Lateral border of the ischial tuberosity
Insertion: Intertrochanteric crest of the femur (the ridge between the greater and lesser trochanters, on the posterior femur)
Action:
Primary: External (lateral) rotation of the hip
Adduction of the hip (its horizontal fiber direction gives it a stronger adduction component than the other deep six)
Stabilization of the femoral head in the acetabulum
Innervation: Nerve to quadratus femoris from the sacral plexus (L4, L5, S1)

Client position: Sidelying, affected side up, hip flexed approximately 45 degrees, pillow between the knees. Alternatively, prone.
Landmark sequence:

Locate the ischial tuberosity — the large bony prominence at the inferior pelvis, palpable through the gluteal tissue in sidelying or prone. It is the "sit bone."
Locate the greater trochanter laterally.
Quadratus femoris runs horizontally from the lateral border of the ischial tuberosity to the intertrochanteric crest. The muscle lies inferior to gemellus inferior and the obturator internus–gemelli complex.
Palpate along a horizontal line from the ischial tuberosity toward the greater trochanter, pressing through gluteus maximus. Quadratus femoris lies at the inferior border of the deep six group — if you are inferior to the piriformis line and at the level of the ischial tuberosity, you are in the correct zone.

Tissue feel: Feels like a flat, broad band running horizontally, distinctly different from the more oblique piriformis above. It is wider and flatter than the cord-like gemelli and obturator internus tendon. When hypertonic, it feels like a taut horizontal strap at the level of the ischial tuberosity.
Confirmation test: Maintain your palpating finger on the suspected muscle. Ask the client to externally rotate the hip against resistance. You should feel contraction. Its horizontal direction and location at the ischial tuberosity level help distinguish it from piriformis (oblique, more superior).
Common errors:
Confusing with hamstring origin — the hamstrings also originate from the ischial tuberosity but run vertically down the posterior thigh. Quadratus femoris runs horizontally from the ischial tuberosity toward the trochanter. If the tissue contracts with knee flexion, you are on hamstrings.
Palpating too superiorly — if you are more than 2 cm above the ischial tuberosity, you are in the gemelli–obturator internus zone, not quadratus femoris.

Common TrP locations: In the muscle belly, approximately midway along its horizontal course from ischial tuberosity to intertrochanteric crest.
Referral pattern: Deep aching in the inferior buttock and posterior hip, concentrated around the ischial tuberosity and the gluteal fold. Can refer to the posterior proximal thigh.
Clinical significance: Quadratus femoris TrP referral to the ischial tuberosity region mimics ischial bursitis and proximal hamstring tendinopathy. In clients with "sit bone pain" that worsens with prolonged sitting, check quadratus femoris — it lies directly over the ischial tuberosity and becomes compressed with sitting, exactly like the hamstring origin.

Trigger point referral diagram — coming soon

Image coming soon. For visual reference, see [Quadratus Femoris at TriggerPoints.net](http://www.triggerpoints.net/muscle/quadratus-femoris).

Common conditions:

Contributes to conditions/piriformis-syndrome differential — as the most inferior of the deep six, quadratus femoris can compress the sciatic nerve or its branches independently of piriformis. In clients with deep buttock pain radiating inferiorly, the entire deep six should be assessed.
Relevant to ischial bursitis and proximal hamstring tendinopathy differential — quadratus femoris TrPs at the ischial tuberosity produce "sit bone pain" identical to these conditions.
Relevant to conditions/hip-osteoarthritis — like the other deep rotators, quadratus femoris guards in response to hip joint degeneration, contributing to external rotation contracture and loss of internal rotation ROM.

What you'll typically find:

Hypertonic alongside the rest of the deep six in chronic sitters. Because it lies at the level of the ischial tuberosity, it is directly compressed against the chair and tends to become tender earlier than the more superior rotators.
In clients with ischial tuberosity pain, the quadratus femoris and the hamstring origin are often both involved. Differentiate by having the client alternately resist external rotation (quadratus femoris) and knee flexion (hamstrings) while palpating the tender point.
Quadratus femoris is easier to identify than the other deep six because of its horizontal fiber direction — it is the only deep six muscle that runs truly horizontally.

Treatment effects:

Responds well to sustained compression and cross-fiber techniques at the ischial tuberosity level. Its flat, horizontal orientation allows effective stripping from ischial tuberosity toward the trochanter.
Because it is the most inferior of the group, it is often the last muscle treated when stripping through the deep six from piriformis downward. It is accessible from both the sidelying and prone positions.
Warm gluteus maximus first — the same rule applies to all deep six treatment.

Cautions:

The sciatic nerve passes superficial to quadratus femoris (between it and the overlying structures). Radiating symptoms during treatment indicate sciatic nerve compression.
The ischial tuberosity region requires clear communication with the client regarding hand placement. Maintain professional boundaries and explain the anatomy.

Clinical pearl:

Quadratus femoris is the best "orientation landmark" when treating the deep six. Find the ischial tuberosity (the "sit bone" — the most reliable bony landmark in the region), then palpate horizontally toward the greater trochanter. You are on quadratus femoris. Everything above this line (moving superiorly) is the gemelli–obturator internus complex, and above that is piriformis. Use quadratus femoris as your anchor and work superiorly through the group.

Resisted external rotation (shared with all deep six):

Client supine with hip and knee flexed to 90 degrees. Resist external rotation at the ankle. Tests the deep rotator group collectively.

Passive hip internal rotation:

Client prone with knee flexed to 90 degrees. Let the foot fall laterally. Less than 30 degrees of internal rotation suggests deep rotator tightness. Quadratus femoris is often the most restricted of the group because of its horizontal fiber direction and strong adduction component.

Deep six hip external rotators (anatomical):

Hip external rotators (functional):

Shared innervation:

anatomy/muscles/gemellus-inferior — shares nerve to quadratus femoris (L4, L5, S1)

Adjacent deep six:

Antagonists (hip internal rotation):

The most inferior and most accessible of the deep six — use it as your orientation landmark and work superiorly through the group.
Horizontal fiber direction distinguishes it from all other deep six muscles (which run obliquely).
"Sit bone pain" with negative hamstring tests — check quadratus femoris TrPs before assuming ischial bursitis or hamstring tendinopathy.