Quadratus femoris muscle
Quadratus femoris is a paired, rectangular-shaped muscle of the gluteal region. It is part of the group of muscles known as the lateral, or external, rotators of the thigh.
Even though it is a small muscle, the quadratus femoris has many important functions; it stabilizes the hip joint by keeping the head of the femur in place and produces external rotation of the thigh in the hip joint when the lower limb is in the anatomical position. In certain positions quadratus femoris can also assist in the movements of abduction and adduction.
In this article, we will discuss the anatomy and function of the quadratus femoris muscle.
|Insertion||Intertrochanteric crest of femur|
|Action||Hip joint: thigh external rotation; stabilizes head of femur in acetabulum|
Nerve to quadratus femoris (L4-S1)
|Blood supply||Inferior gluteal artery|
Origin and insertion
Quadratus femoris originates from the upper part of the lateral border of ischial tuberosity, inferior to the lower rim of acetabulum. This attachment is superior to the origins of adductor magnus muscle and lateral to the obturator externus muscle.
From there this flat muscle runs laterally to insert onto the quadrate tubercle located on the intertrochanteric crest of femur, superior to the insertions of adductor magnus and lateral to triceps coxae muscles.
Like all the small deep gluteal muscles, the posterior surface of quadratus femoris is covered by the gluteus maximus muscle. Anteriorly, the quadratus femoris muscle is in close relation to the tendon of obturator externus muscle, which separates it from the capsule of the hip joint.
Quadratus femoris is the most inferiorly placed of all external rotators of the hip, sitting immediately below the gemellus inferior muscle. Moving inferior still, the adductor magnus muscle can be found. Here, the inferior part of quadratus femoris lies parallel with the superior border of adductor magnus. A gap exists between these two muscles; through which the medial circumflex artery passes. On occasion, these two muscles are fused together, in which case the gap disappears. A bursa may be found between quadratus femoris muscle and lesser trochanter.
Near to the insertion of quadratus femoris the cruciate anastomosis (the anastomosis between medial and lateral circumflex arteries, the gluteal artery and the first perforating artery) is found.
Quadratus femoris muscle is innervated by the nerve to quadratus femoris. This arises from the spinal nerves L4 - S1, derived from the sacral plexus. In addition to quadratus femoris, this nerve innervates also supplies the gemellus inferior muscle and the hip joint.
Quadratus femoris receives its blood supply predominantly from the inferior gluteal artery, a large branch of the internal iliac artery. The smaller part of the muscle can be supplied by the descending branch of the medial circumflex femoral artery. The venous blood is drained by the inferior gluteal vein which is a tributary of the internal iliac vein.
The main action of the quadratus femoris muscle is external (lateral) rotation of the thigh. Although this is a small muscle it is a pretty powerful rotator of the hip, acting synergically with the other external rotators; gluteus maximus, piriformis, superior gemellus and inferior gemellus and obturator internus muscles. Acting together, these muscles produce a strong external rotation of the thigh which is limited by antagonistic muscles and the iliofemoral ligament.
Quadratus femoris muscle is unusual in that it can assist in the production of both abduction and adduction movements of the leg. When the leg is in the anatomical position, quadratus femoris, pectineus and the inferior fibers of gluteus maximus assist the thigh adductor muscles (adductor longus, magnus and brevis) to adduct the thigh at the hip joint. In contrast, when the hip is flexed, quadratus femoris, along with piriformis, superior and inferior gemelli, obturator internus and obturator externus all act to abduct the thigh.
Due to its specific location inside the hip joint, the quadratus femoris muscle is one of the most important stabilizers of this joint. It keeps the head of the femur in place and thus prevents injuries in numerous activities.
To expand your knowledge check out our resources about the muscles of the hip joint.
Groin pain is a pretty common and disabling condition whose cause is often difficult to diagnose without medical imaging, due to there being a number of structures with synergistic functions. One known cause of severe pain in this region is tendinitis of quadratus femoris muscle. Besides physical examination, the diagnosis process often requires magnetic resonance imaging (MRI), which is the reason why accurate diagnosis and treatment of this condition is usually delayed.