Quadratus Femoris
| |
| Quadratus Femoris | |
|---|---|
| Muscle Type | |
| Origin | ateral border of ischial tuberosity (just below inferior gemellus) |
| Insertion | Quadrate tubercle on intertrochanteric crest of femur |
| Action | Laterally rotates thigh; assists in adduction of thigh; stabilizes hip joint |
| Synergists | |
| Antagonists | Gluteus Medius, Gluteus Minimus, Tensor Fascia Lata |
| Spinal innervation | L4, L5, S1 |
| Peripheral Innervation | Nerve to quadratus femoris (L4–S1) |
| Vasculature | Inferior gluteal artery; medial circumflex femoral artery |
The quadratus femoris is a flat, rectangular muscle situated in the deep gluteal region, between the inferior gemellus and the upper margin of adductor magnus. It is one of the short external (lateral) rotators of the hip and also acts as a strong adductor and stabilizer. The term “quadratus” refers to its roughly four-sided shape. Quadratus femoris primarily laterally rotates the femur and helps hold the femoral head in the acetabulum. It is the most inferior muscle in the deep lateral rotator group.
Structure
Quadratus femoris is a short, flat muscle in the deep gluteal region. It is inherently a postural muscle with a high proportion of type I fibers for sustained contraction (hip stabilization). Its fiber orientation is horizontal, spanning from pelvis to femur.
Origin
It originates from the lateral aspect of the ischial tuberosity, specifically the upper external part of the tuberosity, just below where the inferior gemellus originates. This origin is roughly at the same horizontal level as the hip joint. The muscle lies anterior (deep) to the sciatic nerve in this area.
Insertion
It inserts into the quadrate tubercle on the intertrochanteric crest of the femur, and to some extent the bone inferior to it. The intertrochanteric crest is the ridge between the greater and lesser trochanters on the posterior femur. The quadrate tubercle is a slight elevation about midway along this crest. This insertion point allows the muscle to exert a strong external rotation force on the femur.
Action
Its primary function is external (lateral) rotation of the thigh at the hip joint. Because it runs almost directly horizontally, it’s very effective at pulling the femur into external rotation. It also can assist in adduction of the thigh, particularly from a flexed position (when the line of pull falls medial to the joint axis). Additionally, the quadratus femoris serves to steady the femoral head in the acetabulum, functioning as part of the “rotator cuff” of the hip, giving posterior support to the joint capsule. It has no role at the knee since it doesn’t cross it.
Synergists
It works with the other short lateral rotators of the hip: piriformis, obturator internus, obturator externus, superior and inferior gemellus. These muscles often co-contract to externally rotate the femur or stabilize it during complex movements (like when balancing on one foot and turning the torso). During hip extension and external rotation (like standing and turning the foot outward), quadratus femoris and gluteus maximus (especially the lower fibers) act together. Also, adductor magnus (ischiocondylar part) can synergize in external rotation when the hip is near extension (since the posterior part of adductor magnus can contribute to external rotation). For stabilization, quadratus femoris often contracts isometrically with the other rotators to hold the hip steady (e.g., in standing on uneven ground).
Antagonists
The medial (internal) rotators of the hip – gluteus medius and minimus (anterior fibers) and TFL – antagonize quadratus femoris by internally rotating the femur. Additionally, when quadratus femoris assists in adduction, the abductors (gluteus medius/minimus, TFL) oppose that component. But the prime antagonism is in the rotation: internal rotators vs. this external rotator. In posture, if quadratus femoris is tight, it can cause the feet to turn out (external rotation); the internal rotators would then appear weak or overstretched in compensation.
Spinal Innervation
L4, L5, S1 nerve roots (via sacral plexus).
Peripheral Innervation
Nerve to quadratus femoris (ventral rami of L4–S1). This nerve also innervates the inferior gemellus. It runs deep (anterior) to the short rotators, near the hip joint, to reach quadratus femoris from its front side. Because it’s deep, it’s less commonly injured than some other nerves. But entrapment can occur in the ischiofemoral impingement scenario where space between ischium and femur is reduced, potentially affecting this nerve.
Vasculature
Supplied by the inferior gluteal artery (muscular branches) and the medial circumflex femoral artery (which forms part of the cruciate anastomosis). The first perforating artery of the profunda femoris passes near quadratus femoris as well. In essence, multiple small vessels ensure it has blood supply due to the rich anastomotic network in that region. That’s why in ischiofemoral impingement (with edema in quadratus femoris on MRI), vascular compromise isn’t typical – it’s more compression.
Clinical Relevance
Ischiofemoral Impingement: This is a condition where the space between the ischial tuberosity and the femur (lesser trochanter) is narrowed, sometimes entrapping or repeatedly impinging the quadratus femoris muscle. It can cause deep gluteal/posterior thigh pain. MRI may show edema or tearing in the quadratus femoris. Causes include pelvic anatomy variances or after hip surgery (like excess lesser trochanter prominence). Treatment is often conservative: avoiding extreme positions, physiotherapy. In refractory cases, surgical resection of a portion of the lesser trochanter or ischium can increase space. Recognizing this on MRI is key to explaining otherwise mysterious buttock pain.
Piriformis Syndrome Differential: Quadratus femoris issues can mimic piriformis syndrome to a degree (both cause buttock pain). However, quadratus femoris is lower and more likely to cause groin or deep hip pain due to its relation to the hip joint. If a patient’s MRI shows a normal piriformis but an abnormal quadratus femoris, one should consider ischiofemoral impingement rather than piriformis syndrome.
Weak External Rotation: Isolated weakness of quadratus femoris is hard to detect clinically because other rotators compensate. But in certain positions (hip neutral), quadratus femoris is a primary rotator. If it were weak or not functioning, there might be slight weakness in external rotation strength. However, unless nerve to quadratus femoris is out (which would also affect inferior gemellus), you won’t find isolated deficits easily.
Inferior Gemellus Pairing: In anatomy, quadratus femoris and inferior gemellus share functional similarity (both laterally rotate and adduct), though innervation differs. Clinically, they are often considered together when examining deep lateral rotators.
Proximal Hamstring Injuries: Because quadratus femoris is near the hamstring origin, sometimes a complete proximal hamstring avulsion (from ischial tuberosity) can also disrupt quadratus femoris origin or function. Surgeons reattaching hamstrings note the close proximity of quadratus femoris. Scar tissue from hamstring injuries can tether quadratus femoris, possibly leading to reduced external rotation – which is usually subclinical.
Stretching: To stretch quadratus femoris, one would internally rotate and adduct the hip (opposite of its action). Some deep yoga poses (like pigeon with internal rotation) might target it. People with ischiofemoral impingement actually feel pain in those positions because quadratus femoris is being compressed.
Trigger Points: Quadratus femoris trigger points can refer pain to the buttock or posterior thigh. Deep massage or needling to the lateral ischial tuberosity area (if accessible) can sometimes relieve deep buttock pain that isn’t piriformis-related. However, its deep location, beneath the sciatic nerve, makes direct access challenging.
Functional Anatomy: Quadratus femoris significantly contributes to external rotation in extension and controls internal rotation in gait. For example, during the stance phase, when the foot is flat and the leg is bearing weight, quadratus femoris (with other lateral rotators) resists the internal rotation torque that occurs as the pronating foot tries to internally rotate the tibia and femur. A weakened quadratus femoris might thus be implicated in subtle gait deviations (e.g., too much internal rotation of limb during stance). This is theoretical, as usually the lateral rotators as a group are considered.
Relationship with Sciatic Nerve: The sciatic nerve passes superior to quadratus femoris (running just below piriformis and above gemelli/obturator internus). Quadratus femoris lies just below the nerve. In deep gluteal syndrome (sometimes called piriformis syndrome broadly), fibrous bands from quadratus femoris or hypertrophy could conceivably irritate the sciatic nerve from below (though piriformis is more commonly blamed from above). The Hamstrings syndrome (proximal hamstring tendinopathy) can also co-exist with quadratus femoris issues, confusing the diagnostic picture of posterior hip pain. A comprehensive approach will look at all structures in the buttock region on imaging.
