It is defined as a sheet or band of fibrous tissue that extends deep into the skin and that aligns, inverts and separates the internal structures of the body.
There are three general classifications of fascia:
- The superficial fascia: It is mixed with the reticular layer under the dermis.
- The deep fascia: Envelops muscles, bones and neurovascular structures.
- The visceral fascia: Provides membranous investments that suspend organs within their cavities.
The fascia lata is a deep fascial inversion of the entire thigh musculature and is analogous to a strong, extensible and elastic media.
It begins around the iliac crest and the inguinal ligament and ends more distally to the bony prominences of the tibia, where it continues to become the deep fascia of the leg (crural fascia).
The width of the fascia lata varies considerably in the different regions of the thigh.
It is thicker along the superolateral side of the thigh, it originates from the fascial condensations of the gluteus maximus and median, and also around the knee where the fascia receives reinforcing fibers from the tendons.
The fascia is thinner where it covers the adductor muscles of the medial thigh.
The deepest place of the fascia lata gives rise to three intermuscular septa that are centrally joined to the femur.
This divides the musculature of the thigh into three compartments, anterior, medial and lateral.
The lateral intermuscular septum is the strongest of the three due to the reinforcement of the iliotibial tract, while the other two septa are proportionally weaker.
An ovoid hiatus is present in the fascia lata just below the inguinal ligament known as the saphenous opening.
This gap serves as the entry point for the efferent lymphatic vessels and the large saphenous vein, draining into the superficial inguinal lymph nodes and the femoral vein, respectively.
A covering of membranous tissue (the cribiform fascia) covers the hiatus that develops inferomedially from an acute margin of space (the falciform margin).
The iliotibial tract:
The iliotibial tract is a longitudinal thickening of the fascia lata, which is subsequently strengthened by fibers of the gluteus maximus.
It is located laterally on the thigh, extends from the iliac tubercle to the lateral tibial condyle.
The iliotibial tract has three main functions:
- Movement: Acts as an extensor, abductor and lateral rotator of the hip, with additional paper to provide lateral stabilization to the knee joint.
- Compartmentalization: The deepest aspect of the iliotibial tract extends centrally, to form the lateral intermuscular septum of the thigh and joins the femur.
- Muscle sheath: It forms a sheath for the tension muscle of the fascia lata.
Tensor Fascia Lata:
The tensor of the fascia lata is a gluteal muscle that acts as a flexor, abductor and internal rotator of the hip.
However, its nomenclature derives from its additional role in the tension of the fascia lata.
The muscle originates in the iliac crest and descends through the superolateral thigh.
At the junction of the middle and upper thirds of the thigh, it is inserted into the anterior aspect of the iliotibial tract.
When stimulated, the tensor fascia lata tenses the iliotibial band and reinforces the knee, especially when the opposite foot is raised.
The property of the tensor of the fascia lata, of tightening the fascia lata is analogous to lifting an elastic stocking on the thigh.
When the fascia lata is stretched, it forces the muscle groups to come closer to the intermuscular partitions towards the femur.
This action centralizes muscle weight and limits outward expansion, which in turn reduces the total force required for movement in the hip joint.
An additional property of tightening the fascia lata is that it makes the muscle contraction more efficient to compress the deep veins.
This ensures an adequate venous return to the heart from the lower extremities.
The fascia lata forms multiple superior junctions around the pelvis and the hip region:
- Posterior: Sacrum and coccyx.
- Lateral: Iliac crest.
- Anterior: Inguinal ligament, upper pubic branch.
- Medial: Lower ischiopubic branch, ischial tuberosity, sacrotuberous ligament.
The fascia lata is also continuous with regions of deep and superficial fascia in its superior aspect.
The deep iliac fascia descends from the thoracic region in the diaphragm, covers all the iliac and psoas regions and combines with the fascia lata superiorly.
The superficial fascia of the lower abdominal wall (Scarpa’s fascia) and the perineal region combine with the fascia lata just below the inguinal ligament.
The lateral thickening of the fascia lata forms the iliotibial tract and receives tendon insertions superior to those of the gluteus maximus and the tensor of the fascia lata.
The widened band of fibers descends from the lateral thigh and joins the lateral tibial condyle in the anterolateral tubercle.
The fascia lata ends at the knee joint, where it becomes the deep fascia of the leg (Crural fascia).
The accessories are made in the bony prominences around the knee, including the femoral and tibial condyles, the patella, the head of the fibula and the tibial tuberosity.
The deep aspect of the fascia lata produces three intermuscular septa that join centrally to the femur.
The lateral septum joins the lateral lip of the rough line and the medial and anterior septa join the medial lip.
These accessories continue along the entire length of the femur to include the supracondylar lines.