Anatomy Myths – The boundaries of the Vastus Lateralis
Due to the common practice of utilizing 2 dimentional anatomical representations to learn clinical anatomy (ie. text books), there are various misconceptions regarding the actual location, boundaries, and depth of anatomic structure. This fact forms the basis for the development of Functional Anatomic Palpation Systems™ seminars.
One such misconception is in regards to the boundaries of the Vastus Lateralis muscle. Here is a basic review of its anatomic properties:
From: Vastus lateralis has a continuous linear attachment on the femur along the upper half of the intertrochanteric line, the anterior and inferior borders of the greater trochanter, the lateral lip of the gluteal tuberosity and the upper half of the lateral lip of the linea aspera. Additionally, vastus lateralis arises, in part, from the lateral intermuscular septum.
To: Distally, the flattened tendon of vastus lateralis joins the quadriceps femoris tendon. A part of the tendon of vastus lateralis inserts directly into the
upper and lateral borders of the patella. An expansion from the vastus lateralis tendon blends with the lateral aspect of the capsule of the knee joint and the iliotibial tract, before attaching to the lateral tibial condyle.
Innervation: femoral nerve (L2, 3, 4)
Action: extends leg at knee joint; significantly contributes to patellar tracking and function
Due to the presence of the overlying Iliotibial Tract, textbook figures cause the common misconception is that this structure represents the farthest posterior border of this quad muscle (figure 1). However, as can be seen in figure 2, an axillary cadaveric view at mid-thigh level, the boarders of the Vastus Lateralis (VL) extend posteriorly far beyond the posterior perimeter of the ITB.
I recall being at a soft tissue release seminar a while back where one of the instructures noted that he often finds “adhesions” between the ITB and the Biceps
Femoris !!?? This same instructor later spoke of the importance of specific soft tissue palpation skills!!!!!!!!
As can be clearly seen in figure 2, it is the belly of the VL that boarders the posteriorly positioned biceps femoris muscle (BF). Figure 3 is a side view demonstrating the large portion of the VL located posterior to the ITB which runs adjacent to the biceps femoris.
Part of the misconception stems from the fact that anatomical drawings depict the ITB as a clear and separate structure. In fact, the ITB simply represents a lateral thickening of the fascia which surrounds/envelops the entire thigh….the Fascia Latae. Thus the anterior and posterior boarders are almost impossible to clearly distinguish.
This anatomical relationship is important when utilizing specific soft tissue techniques geared at promoting proper inter and intra-layer fascial and soft tissue plane sliding such as Functional Range Release™ technique. In order to promote proper deep fascial layer movement between the VL, BF, and Fascia Latae, knowledge of the anatomy allows the practitioner to select the proper combination of joint movements needed to remove tension between layers thus promoting proper fascial plane mechanics.