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Vastus Lateralis Obliquus Muscle

The vastus lateralis obliquus (VLO) is a specialized distal portion of the vastus lateralis muscle, part of the quadriceps femoris group. The fibers of the VLO run obliquely (approximately 50–55°) medially toward the patella, distinct from the longitudinal fibers of the main vastus lateralis. This orientation gives the VLO an important role in stabilizing the patella and counteracting the lateral pull of the quadriceps during knee extension.

Although anatomically continuous with the vastus lateralis, the VLO is often described as a separate functional subdivision, critical in knee biomechanics and patellofemoral disorders.

Synonyms

  • Oblique portion of vastus lateralis

  • Vastus lateralis obliquus fibers

  • Distal vastus lateralis subdivision

Origin and Insertion

  • Origin: Distal lateral intermuscular septum and lateral femoral shaft, fibers blending with the main vastus lateralis

  • Course: Fibers run obliquely and medially, at ~50–55° angle relative to femoral shaft, distinct from the longitudinal fibers of the proximal vastus lateralis

  • Insertion: Lateral margin of the patella and quadriceps tendon, blending with fibers of the rectus femoris and vastus medialis obliquus

Nerve Supply

  • Femoral nerve (L2–L4)

Arterial Supply

  • Lateral circumflex femoral artery (descending branch)

  • Perforating branches of the profunda femoris artery

Venous Drainage

  • Companion veins of the lateral circumflex femoral artery → profunda femoris vein → femoral vein

Relations

  • Anteriorly: Subcutaneous tissue and skin of anterolateral thigh

  • Posteriorly: Vastus intermedius muscle and femoral shaft

  • Medially: Quadriceps tendon, rectus femoris, and vastus medialis obliquus

  • Laterally: Iliotibial band, tensor fasciae latae

  • Inferiorly: Lateral patellar margin and lateral retinaculum

Function

  • Assists in extension of the knee joint as part of the quadriceps femoris

  • Provides dynamic stabilization of the patella

  • Counters excessive lateral displacement of the patella, balancing the pull of the vastus medialis obliquus (VMO)

  • Important in maintaining proper patellofemoral tracking during gait and sports activities

Clinical Significance

  • Weakness or dysfunction may contribute to patellofemoral pain syndrome

  • Imbalance between VLO and VMO can lead to patellar maltracking and instability

  • Target for strengthening in rehabilitation of knee injuries

  • Recognized in surgical planning for patellar stabilization procedures

MRI Appearance

T1-weighted images:

  • Muscle shows low-to-intermediate signal intensity

  • Fatty septa and surrounding subcutaneous fat appear bright

  • Chronic atrophy or fatty degeneration may increase signal

T2-weighted images:

  • Normal muscle: low-to-intermediate signal intensity

  • Strain, edema, or injury: bright hyperintense signal

STIR (Short Tau Inversion Recovery):

  • Normal: low-to-intermediate signal

  • Pathology (strain, tendinopathy, inflammation): bright hyperintensity

Proton Density Fat-Saturated (PD FS):

  • Normal: low-to-intermediate signal

  • Pathology (tears, edema, bursitis): bright hyperintensity

T1 Fat-Sat Post-Contrast:

  • Normal: mild homogeneous enhancement

  • Pathology (myositis, abscess, tumor): heterogeneous or rim enhancement

CT Appearance

Non-Contrast CT:

  • Appears as homogeneous soft tissue density along anterolateral thigh

  • Surrounding fat planes well defined

  • Hematoma: hyperdense area within fibers

  • Chronic atrophy: low attenuation with fatty replacement

Post-Contrast CT:

  • Normal muscle: mild uniform enhancement

  • Pathology: heterogeneous enhancement in tumor or infection

  • Abscess: rim enhancement with central low density

  • Fat stranding in surrounding tissue indicates inflammation or trauma

MRI image

Vastus Lateralis Obliquus Muscle sag cross sectional anatomy 3T radiology anatomy image-img-00000-00000