Bilateral variations of the psoas major and the iliacus muscles and presence of an undescribed variant muscle--accessory iliopsoas muscle.

Inspite of the detailed description of the iliopsoas muscle complex, interesting variations of its main parts--the psoas major and the iliacus muscles can still be encountered. These variations may clarify some aspects of the embryological development of the iliopsoas and have certain clinical importance because of the frequent co-existence with an unusual femoral nerve by its formation and course. We present in our report a case of bilateral variations of the psoas major and the iliacus muscles combined with variations of the left and the right femoral nerves, which were found during the anatomical dissection of a female human cadaver. The most remarkable finding was noted on the left side, where an undescribed variant muscle accessory iliopsoas, was observed. It was the only finding of such a muscle among 108 human cadavers examined over a period of 22 years. The accessory iliopsoas was formed by the connection of two accessory muscles--accessory psoas major and accessory iliacus. The clinical significance of the described variant muscles and their importance as an additional factor in the femoral neuropathy are also a matter of discussion in our report.