Do the vastus medialis obliquus and vastus medialis longus really exist? A systematic review

Abstract

There remains controversy over whether the vastus medialis (VM) is a single anatomical structure or whether it is composed of two separate portions, the vastus medialis longus (VML) proximally and the vastus medialis obliquus (VMO) distally. The objective of this study was to assess the evidence base of investigations into muscle fiber orientation, presence of a fibrofascial plane, and the innervation of the VM in human cadaver specimens and subjects. In addition to a hand search of specialist journals, an electronic search of AMED, British Nursing Index, CINAHL, the Cochrane database, EMBASE, ovid Medline, Pubmed, and Zetoc were performed from their inception to September 2008. All human subject papers assessing VM fiber orientation, presence of a fibrofascial plane, and the innervation of the VM where reviewed. Twenty-six papers, assessing 699 healthy knees, and 591 specimens with patellofemoral dysfunction were reviewed. The majority of nonpathological and pathological cases presented with a substantial alteration in fiber alignment seen between proximal and distal muscle portions of VM. Both cohorts presented with either one or two nerve branches to the VM. A fibrofascial plane dividing these two muscles was seen in a small proportion of both pathological and nonpathological knees. There was, however, insufficient good quality evidence to state whether the VM is composed of two separate components, the proximal VML and the distal VMO. Further study is recommended to evaluate the pathophysiological implications of such findings and to assess whether these correlate to functional electromyographic findings between the VML and VMO muscles.

Magnetic Resonance Imaging of the Extensor Mechanism

“…There is no consensus in the literature as to whether these two components are separate muscles, or whether they reflect different directional fibers of the same muscle. 2,3 On MR imaging, the normal appearance of the trilaminar quadriceps tendon manifests as low-signal tendon fibers with interdigitating fat (Fig. 1).…”

Validity of measuring distal vastus medialis muscle using rehabilitative ultrasound imaging versus magnetic resonance imaging

“…An example is vastus medialis, where substantial alterations in fibre alignment are seen between proximal and distal muscle portions (Smith et al , 2009). The distal oblique fibres are thought to play a pivotal role in the kinematics and alignment at the patellofemoral joint (Berry et al , 2008, Fagan and Delahunt, 2008, Lin et al , 2008 and physiological or biomechanical dysfunction of this muscle are reported to contribute to patellofemoral pain (PFP) (Lankhorst et al , 2012).…”

Between-day reliability of a method for non-invasive estimation of muscle composition

“…However, the biceps brachii is easy to measure and very rarely used in tensiomyography studies. Furthermore, there is evidence that the vastus medialis is anatomically divided into two muscle heads (obliques and longus) with two separate neural drives (Smith et al, 2009) and should be measured accordingly. In most tensiomyographic studies, the vastus lateralis and biceps femoris muscles have been investigated (Dahmane et al, 2006;Ditroilo et al, 2011;García-Manso et al, 2011a,b;Grabljevec and Tomšič, 2002;Pišot et al, 2008;Rusu et al, 2009;Šimunič et al, 2011); however, no tensiomyographic measurement reliability is reported for those two muscles.…”