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Quadratus femoris muscle

The quadratus femoris is a flat, quadrilateral muscle of the deep gluteal region. It is one of the short external rotators of the hip, located below the gemelli and obturator internus muscles. Despite its relatively small size, it plays an important role in hip joint stability by laterally rotating the femur and reinforcing the posterior hip capsule.

It is also a key anatomical landmark in radiology and surgery, lying between the ischial tuberosity and femur. Pathology in this muscle, such as quadratus femoris tear or ischiofemoral impingement, is increasingly recognized in musculoskeletal imaging.

Synonyms

  • Quadrate muscle of thigh

  • External rotator quadratus femoris

Origin and Insertion

  • Origin: Arises from the lateral border of the ischial tuberosity

  • Course: Runs horizontally and laterally, forming a flat, quadrangular belly posterior to the hip joint capsule

  • Insertion: Attaches into the quadrate tubercle of the intertrochanteric crest of the femur and the area below it

Nerve Supply

  • Nerve to quadratus femoris (L4, L5, S1), a branch of the sacral plexus

Arterial Supply

  • Medial circumflex femoral artery

  • Inferior gluteal artery

  • Obturator artery (minor contribution)

Venous Drainage

  • Corresponding veins drain into the medial circumflex femoral vein, inferior gluteal vein, and internal iliac vein

Function

  • Strong external (lateral) rotation of the femur at the hip

  • Assists in adduction of the thigh

  • Reinforces and stabilizes the posterior aspect of the hip joint capsule

  • Acts as a dynamic stabilizer during walking, running, and pivoting movements

Clinical Significance

  • Ischiofemoral impingement: Narrowing between the ischium and lesser trochanter compresses the quadratus femoris → edema or tear

  • Tears/strain: Present as hip or buttock pain, often seen in athletes

  • Landmark muscle: Used in surgical approaches to the hip and identification of the sciatic nerve

  • Can mimic or mask other deep gluteal pathologies on imaging

MRI Appearance

T1-weighted images:

  • Normal muscle shows low-to-intermediate signal intensity

  • Surrounding fat planes appear bright, aiding delineation

  • Fatty degeneration or chronic atrophy shows higher signal within muscle belly

T2-weighted images:

  • Normal muscle shows low-to-intermediate signal intensity

  • Edema, strain, or acute injury appears as bright hyperintense areas

  • Fibrosis or chronic scarring remains dark

STIR (Short Tau Inversion Recovery):

  • Normal quadratus femoris muscle shows low-to-intermediate signal

  • Pathology such as strain, tear, or ischiofemoral impingement shows bright hyperintensity

Proton Density Fat-Saturated (PD FS):

  • Normal muscle shows Intermediate signal

  • Pathological changes (strain, tear, impingement edema) show bright signal after fat suppression

T1 Fat-Sat Post-Contrast:

  • Normal muscle enhances mildly and uniformly

  • Muscle tear, myositis, or tumor shows heterogeneous enhancement

  • Abscess: rim enhancement with non-enhancing center

CT Appearance

Non-Contrast CT:

  • Appears as a homogeneous soft tissue density posterior to hip joint

  • Surrounded by fat, which helps in defining its borders

  • Calcification or hematoma may appear as localized high density

Post-Contrast CT:

  • Normal muscle enhances mildly and evenly

  • Inflammation or neoplasm produces heterogeneous or irregular enhancement

  • Abscess or necrotic lesion shows rim enhancement with central hypodensity

MRI image

Quadratus femoris muscle MRI AXIAL IMAGE

MRI image

Quadratus femoris muscle MRI CORONAL anatomy image-img-00000-00000

MRI image

Quadratus femoris muscle MRI SAG anatomy image-img-00000-00000_00001

CT image

Quadratus femoris muscle CT axial anatomy image-img-00000-00000