An unusual occurrence of a four-headed psoas major: a case report.

Background: While many structures within the human body demonstrate anatomical variations, this is not typically the case for the iliopsoas muscle complex. However, the present paper describes a case of an anomalous psoas major composed of four different muscular heads in a 78-year-old male cadaver.

Materials and methods: During a routine dissection of the right posterior abdominal wall, an unusual psoas major was observed, measured and photographed.

Results: The psoas major was found to possess four muscular heads, otherwise the anatomy of the wall was normal.

Conclusions: The presence of so many heads could interfere with the functions of the psoas major muscle. Therefore this anatomical variation merits further study.