Quadratus Femoris

The quadratus femoris is a short, flat, rectangular muscle located in the deep gluteal region. It extends laterally from the ischial tuberosity to the posterior aspect of the proximal femur and is one of the principal short lateral rotators of the hip.^[1][2]

The muscle lies inferior to the inferior gemellus and obturator internus-gemelli complex and superior to the proximal attachment of adductor magnus. Its broad, approximately horizontal fibers give it the quadrangular appearance reflected in its name.

Quadratus femoris primarily produces lateral rotation of the thigh and assists in stabilizing the femoral head within the acetabulum. It can also contribute to adduction of the thigh. Its close relationships with the sciatic nerve, nerve to quadratus femoris, medial circumflex femoral vessels, and ischiofemoral space make it an important anatomical and clinical landmark.

Location

Quadratus femoris lies in the deep inferior part of the gluteal region, deep to gluteus maximus. It extends between the ischial tuberosity medially and the posterior proximal femur laterally.

The muscle is positioned immediately inferior to the inferior gemellus. Its fibers pass almost horizontally across the posterior aspect of the hip region.

Although classified with the deep gluteal muscles, quadratus femoris lies near the transition between the gluteal region and the proximal posterior and medial thigh.

General Anatomy

Feature	Anatomy
Muscle	Quadratus femoris
Region	Deep gluteal region
Shape	Flat and quadrangular
Origin	Lateral border of ischial tuberosity
Insertion	Quadrate tubercle and adjacent intertrochanteric crest of femur
Innervation	Nerve to quadratus femoris
Root values	L4, L5, S1
Principal actions	Lateral rotation, stabilization and weak adduction of thigh

Origin

Quadratus femoris originates from the lateral border of the ischial tuberosity.^[1][3] The attachment occupies a region of the ischial tuberosity adjacent to the origins of several other muscles.

The ischial tuberosity also provides attachment for the hamstring muscles and inferior gemellus. The origin of quadratus femoris lies lateral to much of the hamstring origin.

From this broad medial attachment, the fibers pass laterally toward the posterior surface of the proximal femur.

Insertion

Quadratus femoris inserts onto the quadrate tubercle on the intertrochanteric crest and the adjacent area of the posterior femur.

The quadrate tubercle is located on the posterior proximal femur along the intertrochanteric crest, which extends between the greater and lesser trochanters.

The broad femoral insertion reflects the relatively rectangular configuration of the muscle and distinguishes it from the more tendinous insertions of several neighboring short lateral rotators.

Course

The fibers of quadratus femoris pass almost horizontally from medial to lateral. The muscle spans the interval between the ischium and proximal femur.

Its line of pull passes posterior to the longitudinal axis of the hip joint. Contraction therefore produces lateral rotation of the femur.

Because the muscle has a relatively broad origin and insertion and lies close to the hip joint, it is also well positioned to contribute to dynamic stabilization.

Deep Gluteal Muscle Arrangement

Quadratus femoris is the most inferior of the commonly described short lateral rotators visible in a posterior dissection of the gluteal region.

From superior to inferior, the characteristic arrangement includes:

• Piriformis
• Superior gemellus
• Obturator internus tendon
• Inferior gemellus
• Quadratus femoris

Obturator externus is also a short lateral rotator, but its course is deeper and differs from this layered posterior arrangement.

Relationship to Inferior Gemellus

The inferior gemellus lies immediately superior to quadratus femoris. It arises from the ischial tuberosity and blends with the inferior surface of the obturator internus tendon.

Both inferior gemellus and quadratus femoris are supplied by the nerve to quadratus femoris. Their shared innervation corresponds with their close anatomical and functional relationship.

A small interval may separate the two muscles, although their boundaries can sometimes appear closely approximated during dissection.

Relationship to Obturator Internus

The tendon of obturator internus lies superior to quadratus femoris, separated from it by the inferior gemellus.

Obturator internus and quadratus femoris both contribute to lateral rotation and stabilization of the hip but differ in their origins, insertions, and innervation.

The obturator internus tendon passes toward the medial surface of the greater trochanter, whereas quadratus femoris inserts more inferiorly onto the intertrochanteric crest.

Relationship to Obturator Externus

The tendon of obturator externus passes posterior to the femoral neck toward the trochanteric fossa. It lies deep and superior to portions of quadratus femoris near the proximal femur.

Both muscles produce lateral rotation, but obturator externus is supplied by the obturator nerve, while quadratus femoris is supplied by a direct branch of the sacral plexus.

Relationship to Gluteus Maximus

Quadratus femoris lies deep to gluteus maximus. The large gluteus maximus covers the short lateral rotators and the major neurovascular structures in the deep gluteal region.

When gluteus maximus is reflected during anatomical dissection, quadratus femoris becomes visible below the gemelli-obturator internus complex.

Both muscles can produce lateral rotation, although gluteus maximus is also a major extensor of the hip.

Relationship to Adductor Magnus

The superior fibers of adductor magnus lie inferior and medial to quadratus femoris. The two muscles occupy adjacent regions near the ischial tuberosity and proximal femur.

Quadratus femoris passes transversely toward the intertrochanteric crest, whereas adductor magnus descends extensively along the medial and posterior femur.

Their close relationship marks the transition from the deep gluteal region to the proximal medial thigh.

Relationship to the Sciatic Nerve

The sciatic nerve exits the pelvis inferior to piriformis and descends through the gluteal region. It passes superficial to the obturator internus-gemelli complex and quadratus femoris.

Quadratus femoris therefore forms part of the muscular bed deep to the sciatic nerve.

As the sciatic nerve continues toward the posterior thigh, it passes over the region between the ischial tuberosity and greater trochanter, making the anatomy of quadratus femoris relevant to deep gluteal nerve entrapment.

Relationship to the Nerve to Quadratus Femoris

The nerve to quadratus femoris is a branch of the sacral plexus. It exits the pelvis through the greater sciatic foramen inferior to piriformis.

The nerve passes deep to the sciatic nerve and travels along the anterior surfaces of the deep gluteal muscles toward quadratus femoris.

It supplies both quadratus femoris and inferior gemellus. It also provides an articular branch to the hip joint.

Because the nerve approaches quadratus femoris on its deep surface, it is not usually visible during a superficial posterior exposure unless the muscle is displaced or reflected.

Relationship to the Hip Joint

Quadratus femoris lies posterior to the proximal femur and close to the posterior-inferior aspect of the hip joint.

The nerve to quadratus femoris provides an articular branch to the hip, reinforcing the anatomical association between the muscle's neurovascular pathway and the joint.

The muscle's proximity to the hip allows it to contribute to dynamic stabilization of the femoral head during rotation and weight-bearing movements.

Relationship to the Medial Circumflex Femoral Artery

The medial circumflex femoral artery has an important relationship with the deep muscles around the proximal femur. Its deep branches pass posteriorly toward the femoral neck and participate in the vascular supply of the femoral head.

The vessel courses in the region between or adjacent to the deep hip muscles, including quadratus femoris and neighboring structures.

This relationship is surgically important because branches of the medial circumflex femoral artery provide a major contribution to the blood supply of the femoral head.

Ischiofemoral Space

The ischiofemoral space is the interval between the ischium and the proximal femur. Quadratus femoris occupies an important portion of this region.

The muscle lies between the ischial tuberosity medially and the femur laterally. Its position makes it particularly susceptible to changes in the dimensions of the ischiofemoral interval.

Narrowing of this space may compress or irritate quadratus femoris, a relationship that forms the anatomical basis of ischiofemoral impingement.

Innervation

Quadratus femoris is supplied by the nerve to quadratus femoris, a branch of the sacral plexus containing fibers primarily from L4, L5, and S1.

The nerve arises from the anterior divisions of the relevant spinal nerve contributions to the sacral plexus. It leaves the pelvis through the greater sciatic foramen inferior to piriformis.

It passes deep to the sciatic nerve and obturator internus-gemelli complex before entering the deep surface of quadratus femoris.

Nerve to Quadratus Femoris

Feature	Anatomy
Origin	Sacral plexus
Root values	L4, L5, S1
Pelvic exit	Greater sciatic foramen inferior to piriformis
Muscular branches	Quadratus femoris and inferior gemellus
Articular branch	Hip joint

The nerve's deep course distinguishes it from the much larger sciatic nerve, which lies superficial to the deep lateral rotator muscles.

Blood Supply

Quadratus femoris receives blood from branches of the medial circumflex femoral artery and inferior gluteal artery, with contributions from the regional arterial anastomoses.

The medial circumflex femoral artery is especially important around the posterior proximal femur and participates in the vascular network supplying the hip region.

The inferior gluteal artery enters the gluteal region inferior to piriformis and supplies gluteus maximus and several neighboring deep structures.

Actions

Lateral Rotation

The principal action of quadratus femoris is lateral rotation of the thigh at the hip joint.

Its fibers extend from the ischial tuberosity to the posterior proximal femur. Because its line of pull lies posterior to the longitudinal axis of the hip, contraction rotates the anterior surface of the femur laterally.

The muscle acts with piriformis, obturator internus, the gemelli, obturator externus, and gluteus maximus.

Adduction

Quadratus femoris can assist in adduction of the thigh. Its transverse orientation allows a medial component of force to be exerted on the proximal femur.

This adducting action is weaker than that of the major adductor muscles and is usually considered secondary to its role in lateral rotation.

Hip Stabilization

Quadratus femoris helps stabilize the femoral head within the acetabulum. Its short length and close proximity to the hip joint allow it to generate compressive forces across the joint.

This function is shared with the other short lateral rotators, which collectively contribute to fine control of femoral position during movement.

Functional Role

Quadratus femoris should not be viewed solely as a muscle that produces external rotation. Its anatomical position allows it to contribute to controlled movement of the proximal femur while maintaining hip stability.

During weight-bearing activities, the muscle works with other deep rotators and gluteal muscles to regulate rotational forces transmitted between the pelvis and lower limb.

Its contribution depends on hip position and the actions of surrounding muscles.

Comparison with Other Lateral Rotators

Muscle	Origin	Insertion	Innervation
Piriformis	Anterior sacrum	Greater trochanter	Nerve to piriformis
Superior gemellus	Ischial spine	With obturator internus tendon	Nerve to obturator internus
Obturator internus	Internal obturator membrane and surrounding bone	Medial surface of greater trochanter	Nerve to obturator internus
Inferior gemellus	Ischial tuberosity	With obturator internus tendon	Nerve to quadratus femoris
Quadratus femoris	Ischial tuberosity	Quadrate tubercle and intertrochanteric crest	Nerve to quadratus femoris
Obturator externus	External obturator membrane and surrounding bone	Trochanteric fossa	Obturator nerve

Relationship to Inferior Gemellus Innervation

The shared nerve supply of quadratus femoris and inferior gemellus is a useful anatomical distinction within the short lateral rotator group.

The inferior gemellus lies superior to quadratus femoris but receives a branch from the same nerve. By contrast, the superior gemellus is supplied by the nerve to obturator internus.

This neural arrangement provides a useful way of distinguishing the otherwise closely related gemelli.

Anatomical Variations

Quadratus femoris may vary in thickness, width, and the precise extent of its attachments to the ischium and femur. Its relationship to the surrounding muscles and neurovascular structures may also vary.

The size of the muscle and the dimensions of the ischiofemoral space differ between individuals. These differences can influence the appearance of the region on cross-sectional imaging.

Variations in the branching pattern of the nerve to quadratus femoris and regional arterial vessels may also occur.

Clinical Significance

Ischiofemoral Impingement

Ischiofemoral impingement refers to abnormal narrowing of the space between the ischium and proximal femur, potentially resulting in compression or irritation of quadratus femoris.

Because the muscle occupies this interval, repetitive compression can produce edema or structural changes that may be visible on MRI.

Clinical symptoms can overlap with other causes of deep gluteal, groin, or posterior hip pain, so imaging findings must be interpreted together with the clinical presentation.

Quadratus Femoris Muscle Edema

Edema of quadratus femoris can be demonstrated on MRI and may occur with ischiofemoral impingement, muscle strain, trauma, or other regional abnormalities.

The location of signal abnormality within the muscle and the dimensions of the surrounding spaces can help characterize the underlying process.

Muscle edema alone is not specific to a single diagnosis and should be interpreted in the context of the surrounding anatomy.

Muscle Strain

Quadratus femoris can be injured during forceful hip rotation, rapid changes in direction, or other movements that load the deep rotator muscles.

Because it lies deep to gluteus maximus, isolated injury can be difficult to identify through surface examination alone.

MRI can demonstrate edema, fiber disruption, hematoma, or other changes associated with muscular injury.

Deep Gluteal Syndrome

Quadratus femoris forms part of the anatomical floor of the deep gluteal space. The sciatic nerve passes superficial to the muscle before continuing into the posterior thigh.

Abnormalities within the deep gluteal region may alter the relationship between the sciatic nerve and surrounding structures. Quadratus femoris is therefore relevant when considering non-discogenic causes of sciatic nerve irritation.

Posterior Hip Surgery

Quadratus femoris is an important landmark during posterior and posterolateral approaches to the proximal femur and hip.

Its relationship to the sciatic nerve, medial circumflex femoral vessels, and other short lateral rotators requires careful identification during deep dissection.

Knowledge of the vascular anatomy is particularly important because branches supplying the femoral head travel through the posterior proximal femoral region.

Imaging

Quadratus femoris is readily identified on MRI and CT. On axial imaging, it appears between the ischial tuberosity medially and the proximal femur laterally.

MRI provides detailed assessment of muscle size, edema, fatty atrophy, tears, and abnormalities of the ischiofemoral space.

The muscle's rectangular configuration and characteristic position inferior to the obturator internus-gemelli complex help distinguish it from neighboring structures.

Surface Anatomy

Quadratus femoris cannot normally be isolated by direct surface palpation because it lies deep to gluteus maximus and the sciatic nerve.

Its approximate course extends horizontally from the ischial tuberosity toward the posterior proximal femur near the intertrochanteric crest.

The muscle is best understood through its relationship to the ischial tuberosity, inferior gemellus, sciatic nerve, ischiofemoral space, and quadrate tubercle. These landmarks define its position as the most inferior of the major short lateral rotators encountered in the deep posterior gluteal region.