The fascia lata is a deep fascial investment of the musculature of the thigh, analogous to a strong, extensible, and elasticated stocking. It arises proximally around the iliac crest and inguinal ligament and extends distally to the bony prominences of the tibia. It is continuous with the deep fascia of the leg, also known as the crural fascia. The thickness of the fascia lata varies throughout the thigh, from thickest along the superolateral aspect of the thigh, to thinnest where it covers the adductor muscles of the medial thigh.
The deepest aspect of the fascia lata gives rise to three intermuscular septa that attach centrally to the femur. These septa divide the thigh musculature into three compartments; the anterior, medial, and lateral compartments, with the lateral intermuscular septum being the strongest due to reinforcement from the iliotibial tract (ITT), and the other two septa being proportionately weaker.
An ovoid hiatus known as the saphenous opening is present in the fascia lata just inferior to the inguinal ligament. This opening serves as an entry point for efferent lymphatic vessels and the great saphenous vein, draining into the superficial inguinal lymph nodes and the femoral vein respectively.
The iliotibial tract (ITT), also known as the iliotibial band or IT band, is a longitudinal thickening of the fascia lata. It is fortified by fibres from the gluteus maximus and is located laterally in the thigh, extending from the iliac tubercle to the lateral tibial condyle. The ITT has three main functions- movement, compartmentalisation, and muscular sheath formation.
The tensor fascia lata (TFL) is a gluteal muscle that acts as a flexor, abductor and internal rotator of the hip. Despite its name, its primary function is to tense the fascia lata. It is innervated by the superior gluteal nerve, and is located more anterolaterally than the other gluteal muscles. When stimulated, the TFL tautens the iliotibial band and braces the knee, especially when the opposite foot is lifted.
The ability of TFL to tighten the fascia lata is analogous to hoisting an elastic stocking up the thigh. When the fascia lata is pulled taut it forces muscles in the anterior and posterior compartments closer towards the femur. This centralizes muscle weight and limits outward expansion, reducing the overall force required for movement at the hip joint. Additionally, it makes muscle contraction more efficient in compressing deep veins, ensuring adequate venous return to the heart from the lower limbs.
The fascia lata has numerous superior attachments around the pelvis and hip region- posteriorly to the sacrum and coccyx, laterally to the iliac crest, anteriorly to the inguinal ligament and superior pubic rami, and medially to the inferior ischiopubic rami, ischial tuberosity, and sacrotuberous ligament. It is continuous with areas of deep and superficial fascia at its superior aspect, such as the deep iliac fascia, which descends from the thoracic region at the diaphragm, covers the entire iliacus and psoas regions, and blends with the fascia lata at the junction of the middle and upper thirds of the thigh.
The fascia lata is a strong fascial band that wraps around the thigh, stretching from the lateral part of the hip to the lower leg. It is a continuation of the deep layer of the superficial fascia of the abdominal wall, known as Scarpa's fascia, and blends with the fascia lata just below the inguinal ligament. The fascia lata is continuous with the deep fascia of the leg, also referred to as the crural fascia. Its thickness varies considerably, being thickest along the superolateral aspect of the thigh, where it arises from the fascial condensations of gluteus maximus and medius. It is also thick around the knee, where it receives reinforcement from tendons of the quadriceps muscles. The fascia lata is thinnest where it covers the adductor muscles of the medial thigh.
The deep aspect of fascia lata produces three distinct intermuscular septa which attach centrally to the femur. The lateral septum joins to the lateral lip of the linea aspera and the medial and anterior septa attach to the medial lip. These attachments then continue along the whole length of the femur to incorporate the supracondylar lines. The septa divide the thigh musculature into three compartments; anterior, medial, and lateral. The lateral intermuscular septum is the strongest of the three due to reinforcement from the iliotibial tract (ITT). The ovoid hiatus known as the saphenous opening is present in the fascia lata just inferior to the inguinal ligament. It serves as a pathway for efferent lymphatic vessels and the great saphenous vein, which drain into the superficial inguinal lymph nodes and the femoral vein respectively.
The iliotibial tract (ITT) is a longitudinal thickening of the fascia lata that is strengthened superoposteriorly by fibres from the gluteus maximus. It is located laterally in the thigh, extending from the iliac tubercle to the lateral tibial condyle and has three major functions:
Dermatofasciotomy and debridement can leave large wound sites that require post-operative grafts to facilitate tissue regeneration and healing. The fascia lata graft is a popular choice due to the iliotibial tract's high concentration of connective tissue fibres, which can be harvested whilst leaving the majority of fibres intact. Novel developments in transplantation have also seen success with using fascia lata in reconstructive surgery, including heart valve replacements, eyelid reparations, dura mater repair, and urinary incontinence treatment (fascia lata sling). One of the main advantages of using fascia lata as opposed to an artificial product is that the native tissue is well vascularised upon transplantation, unlike the latter which may require microvascular anastomosis.
A femoral hernia develops when an out-pouching of abdominal viscera protrudes through the femoral canal. This protrusion becomes visible when it exits superficially through the saphenous opening within the fascia lata, which produces a swelling inferior to the inguinal ligament. The saphenous opening and the surrounding fascia lata are relatively small and inflexible, meaning femoral hernias carry high risk of bowel incarceration or strangulation- necessitating rapid surgical intervention.
The tensor fascia lata (TFL) is a gluteal muscle located more anterolaterally than the gluteus medius and gluteus minimus muscles, and is innervated by the superior gluteal nerve. It originates from the iliac crest and descends inferiorly to the superolateral thigh, terminating at the anterior aspect of the iliotibial tract. Contraction of the muscle pulls tautly the fascia lata, which is analogous to hoisting an elastic stocking up the thigh. Centralizing the muscles and compressing deep veins of the lower limb, it torque the hip joint for improved movement efficiency, as well as reduce the force required for movement.
The fascia lata has four superior attachments around the pelvis and hip region: the sacrum and coccyx (posteriorly), iliac crest (laterally), inguinal ligament and superior pubic rami (anteriorly), and inferior ischiopubic rami, ischial tuberosity, and sacrotuberous ligament (medially). Furthermore, the superior part of the fascia lata is ongoing with both the deep iliac fascia from the thoracic region of the diaphragm, and the deep layer of the superficial fascia of the abdominal wall (Scarpa’s fascia).
The lateral thickening of the fascia lata forms the iliotibial tract, where the gluteus maximus and tensor fascia lata insert superiorly. Descending down the lateral thigh, the band attaches to the lateral tibial condyle on the anterolateral (Gerdy) tubercle. At the knee joint, the fascia lata transitions into the deep fascia of the leg (crural fascia), and attaches to the femoral and tibial condyles, patella, head of fibula, and tibial tuberosity. Moreover, the deep aspect of fascia lata produces three intermuscular septa that attach to the femur, with the lateral septum joining to the lateral lip of the linea aspera, and the medial and anterior septa connecting to the medial lip. These attachments continue along the femur, up to the supracondylar lines.
In reconstructive surgery, dermatofasciotomy and debridement can leave large wound sites that require post-operative grafts for tissue regeneration and healing. In this situation, the fascia lata graft is a popular choice due to the high concentration of connective tissue fibres in the iliotibial tract. Furthermore, novel developments in transplantation have successfully applied the fascia lata in the surgeries of heart valve replacements, eyelid reparations, dura mater repair, and urinary incontinence treatment (fascia lata sling).
The main advantage of using fascia lata over an artificial product is that its native tissue is well vascularised upon transplantation, while the latter may require microvascular anastomosis.
