Magnetic resonance imaging of anomalous leg muscles: accessory soleus, peroneus quartus and the flexor digitorum longus accessorius.

Since the availability of magnetic resonance imaging (MRI), the suspected diagnosis of an accessory muscle of the lower extremity can now be confirmed without the need for invasive procedures. The accessory soleus, peroneus quartus, and flexor digitorum longus accessorius are anomalous muscles of the lower extremity that can be diagnosed by MRI. These accessory muscles are probably more common than once thought and can now be easily distinguished from other space occupying lesions that can occur around the ankle. MRI of these anomalous muscles enables one to make a definitive diagnosis without a biopsy. In those symptomatic patients, the origins and insertions of these accessory muscles can be accurately evaluated by MRI prior to any anticipated surgical intervention.