Takeaway

The IT band functions as part of a three-dimensional system with connections above to the gluteus maximus, gluteus medius, and tensor fascia lata; below to the lateral knee; and deep to the femur via the lateral intermuscular septum.

Anatomical drawings and dissection images often depict the iliotibial (IT) band as a two-dimensional “strap” on the lateral thigh, leaving us with an incomplete picture that doesn’t exactly match what we feel beneath our hands. Broadening our understanding of this tissue to include a three-dimensional view of the deep fascia of the entire thigh, the fascia lata, can help us refine our touch and inspire different possibilities of how to approach it in our sessions.

Where Does It Live?

The IT band can be found within the deep fascia of the thigh, superficial to the vastus lateralis, spanning the entire distance between the iliac crest and the lateral condyle of the tibia, crossing both the hip and knee joints. Before we go into more detail about the IT band specifically, let’s look at how deep fascia is organized as a whole. 

Beneath the skin and soft subcutis, a strong, thin membrane, rich in dense collagen fibers, fully envelops the limbs, covering all the muscles like a single sleeve or stocking. Generally called deep fascia, specific names are used based on region. On the lower limb, the deep fascia of the leg (below the knee) is named crural fascia, and the deep fascia of the thigh (above the knee) is named fascia lata (Image 1). The inner surface of this membrane forms walls or septa that dive to the bone, dividing groups of muscles into compartments. In the thigh, there are three septa, which separate the quadriceps, hamstrings, and adductors into three distinct compartments (Image 2).

So where is the actual IT band in all this? This is where things get interesting. While all mammals have fasciae latae, only humans have IT bands.  

Where Does It Come From?

Deep fascia in both humans and mammals remodels itself in response to load. However, the fascia lata is loaded differently in humans because of bipedalism.¹ Walking upright on two legs generates powerful forces directly into the fascia lata by the gluteus maximus, gluteus medius, and tensor fascia lata (TFL).² Regular and repetitive strain on the fascia lata initiates a remodeling response, slowly causing thicker, denser collagen fibers to be laid down, eventually leading to the development of your IT bands. Since your first steps, every stride, jog, hop, jump, and running leap has been loading your fascia lata, with the most heavily loaded fibers running along the lateral side of the thigh to the knee. The IT band becomes a lateral reinforcement of the fascia lata; you get it from being an upright human who stands, walks, and runs.

What Does It Look Like? 

The fascia lata (including the IT band) is easily identified on the thigh by its perfectly aligned, longitudinally arranged, silvery-white collagen fibers. These fibers form a strong, thin, bi- or tri-laminar sheet with an average thickness of 1 millimeter.³ It looks a lot like filament strapping tape you may have used at the post office. The IT band appears as a gradual thickening of the fascia lata, measuring an average of 3.4 millimeters⁴ at the thickest areas located at the greater trochanter and the lateral knee. The IT band arises so gradually, it is impossible to make a clear line of separation between it and the fascia lata.⁵ That means in the pictures you have seen, the edges of the IT band were created based on the dissector’s or artist’s somewhat arbitrary choice of division (Image 3). 

What Does It Feel Like?

To feel your IT bands while seated, start with flat fingers at the crest of the ilium and gently sink into the soft subcutis, dragging it from side to side as you feel for the firm tissue layer beneath. Continue this motion distally down the lateral thigh, across the greater trochanter, and along the path of the gluteus maximus and TFL insertions until you reach the lateral condyle of the tibia near the knee. You won’t feel any edges of the IT band, but you will likely feel an increased density or toughness of the deep fascia compared to the rest of the thigh. 

Moving slightly posteriorly along this same path, you also may notice a depression between the vastus lateralis and the biceps femoris longus. Often mistaken for the posterior edge of the IT band, in reality this groove is where the fascia lata’s lateral septum dives down to the linea aspera of the femur. Softly sinking your finger pads into this depression, you can palpate the fascia lata three dimensionally as it separates the anterior and posterior compartments of the thigh. 

Grasp and gently lift the vastus lateralis anteriorly (and the fascia lata along with it!) for a different approach to palpating and stretching the IT band. Visualize the fascia lata wrapping around the quadriceps and see if you can perceive any gliding between them. The vastus lateralis should be able to glide freely in relationship to the IT band. However, if the thin layer of loose connective tissue between the muscle and the deep fascia becomes less fluid due to overuse, underuse, inflammation, or age, that movement could be impeded and cause pain. 

Why We Care

Many of our clients arrive in our treatment rooms with IT band pain or even a diagnosis of IT band syndrome with pain at the lateral knee. Others have been told they have a tight IT band and they need to stretch or roll it out. As our anatomical understanding of the IT band becomes more informed, we better understand its relationships to muscles, other fascial structures, and bone. Our improved three-dimensional understanding translates to our touch by helping us perceive the tissues with more detail, which helps us refine our techniques and become more effective therapists. 

Notes

1. James Earls, Born to Walk: Myofascial Efficiency and the Body in Movement, 2nd ed. (Berkeley: North Atlantic Books, 2020).

2. A. Stecco et al., “The Anatomical and Functional Relation Between Gluteus Maximus and Fascia Lata,” Journal of Bodywork and Movement Therapies 17, no. 4 (2013): 512–17; an estimated 70 percent of the gluteus maximus’s distal fibers insert directly into the lateral fascia lata. The tensor fascia lata is fully embedded within the fascia, with its job—tensioning the fascia lata—conveniently described in its name.

3. A. Stecco et al., “Pectoral and Femoral Fasciae: Common Aspects and Regional Specializations,” Surgical and Radiologic Anatomy 31, no. 1 (2009): 35–42.

4. L. A. Goh et al., “Iliotibial Band Thickness: Sonographic Measurements in Asymptomatic Volunteers,” Journal of Clinical Ultrasound 31, no. 5 (2003): 239–44.

5. A. Stecco et al., “The Anatomical and Functional Relation Between Gluteus Maximus and Fascia Lata.”