Iliotibial tract

Origin and insertion

The iliotibial tract is a band of thick connective tissue that runs along the lateral aspect of the thigh. It is part of the deep fascia of the thigh (fascia lata). The superior portion of the iliotibial tract splits into two layers, with the superficial part attaching to the lateral aspect of the Iliac crest (lateral aspect of external lip, iliac tubercle) and the deep part attaching to the lateral aspect of the hip joint capsule.

The iliotibial tract acts as an aponeurosis for two muscles of the pelvis; the tensor fasciae latae and the gluteus maximus. The superficial and deep parts of the iliotibial tract surround the tensor fasciae latae muscle, anchoring the muscle to the ilium and providing an aponeurotic attachment for its distal aspect. The tensor fasciae latae insertion into the fascial tract occurs around one third of the way down the tract’s length. As for the gluteus maximus muscle, about three quarters of its superficial fibers insert into the iliotibial tract, directly inferior to the tensor fasciae latae insertion (the remaining deep fibers attach to the gluteal tuberosity of the femur). In this manner, both these muscles influence the function of the iliotibial tract, and act through the iliotibial tract to produce movements of the thigh.

The iliotibial tract passes over the lateral epicondyle of the femur as it descends down the distal lateral thigh to the knee joint. As it descends, it is anchored to the femur via fibrous strands passing to the lateral femoral intermuscular septum. The tract stops at the level of the knee, inserting into the tubercle of iliotibial tract (Gerdy’s tubercle) which is located on the anterolateral aspect of the lateral condyle of the proximal tibia.

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Relations

The iliotibial tract is part of the deep fascia of the thigh and, as such, fibers from the tract blend with the surrounding deep fascia including those of the lateral femoral intermuscular septum. At the knee, the tract receives fibers from the lateral patellar retinaculum and the joint capsule of the knee. Here, a small recess exists between the lateral femoral epicondyle and the iliotibial tract. This recess contains a synovial extension of the knee joint capsule, the lateral synovial recess.

At the iliotibial tracts' proximal aspect, the tract lies superficial to the gluteus medius and gluteus minimus muscles. The deeper fibers of the gluteus maximum muscle pass deep to the iliotibial tract to insert into the gluteal tuberosity, between the vastus lateralis and adductor magnus muscles. The rectus femoris origin arises nearby the deep insertion of the iliotibial tract, and some blending of the fibers may occur. There are also a number of bursa in the area, including

• Trochanteric bursa of gluteus maximus muscle: between the gluteus maximus muscle (superior fibers) and the greater trochanter of femur.
• Ischial bursa of gluteus maximus muscle: between the gluteus maximus muscle (inferior aspect) and the ischial tuberosity. This bursa may be absent. Other names: Isciatic bursa of gluteus maximus muscle, Sciatic bursa of gluteus maximus muscle.
• Gluteofemoral bursa: between the iliotibial tract and the proximal attachment of vastus lateralis. Other names: Intermuscular gluteal bursae.

At its distal aspect, the iliotibial tract lies superficially to the vastus lateralis head of the quadriceps femoris, where some of the vastus lateralis fibers may blend with the tract. Its insertion at Gerdy’s tubercle is anterior to that of the bicep femoris insertion into the head of fibula. Some sources discuss the presence of an iliotibial bursa, while other sources doubt it’s existence, research conducted by Fairclough et al (2006) into the the etiology of iliotibial band syndrome did not find the presence of this bursa in any of their study cadavers. Texts that do mention its presence describe the location of this bursa as being between the distal part of the iliotibial band, near the insertion on Gerdy’s tubercle and the adjacent tibial surface.

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Innervation

The iliotibial tract shares innervation with the tensor fasciae latae and gluteus maximus muscles, the superior gluteal nerve (L4-S1) and the inferior gluteal nerve (L5-S2).

Blood Supply

The iliotibial tract receives arterial blood from the superior gluteal artery (SGA) and from the ascending branch of the lateral femoral circumflex artery (LFCA). This is the same blood supply received by the tensor fasciae latae.

Function

The connective tissue fibers of the iliotibial tract have very little flexibility, this allows the tract to provide a number of structural and postural functions. It provides lateral stability to the hip and knee joints, it can help return blood to the heart and it acts as a long tendon for the gluteus maximus muscle and tensor fasciae latae, allowing these muscles to exert their function on the thigh and leg.

The iliotibial tract has a postural function, whereby it helps to maintain the body in an upright position. It does this by providing lateral stability to both the hip and the extended knee. At the hip joint it can help prevent pelvic tilting, while at the knee it acts to stabilise the femur on the tibia counteracting any lateral sway movement of the body. This allows for a strong pillar-like structure on which we can stand (especially if standing on one leg) or helping to stabilise the pelvis during locomotion.

The deep fascia of the lower limb forms a strong cylinder like stocking around the muscles of the thigh. This acts to limit the muscles outward expansion during contraction, which assists in compressing veins and returning blood back towards the heart.

Lastly, as the aponeurosis for the tensor fasciae latae and gluteus maximus muscles, the iliotibial tract is the means by which these muscles assert their actions. To learn more about the functions of the muscles , check out these Kenhub articles.

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