A rare muscle variation – accessory piriformis muscle

Year 2018, Volume: 12 Issue: 3, 152 - 154, 31.12.2018

Albert Gradev Lina Malinova Lazar Jelev

Abstract

During routine anatomical dissection of the right lower limb of a
68-year-old male cadaver, a rare muscle variation was revealed and identified
as an accessory piriformis muscle. This variant muscle started from the
anterior surface of the sacrum below the usual piriformis muscle and extended
in a well-identifiable lateral tendon also inserting to the greater trochanter
of the femur. In the case described, the accessory piriformis pierced through
the proximal part of the sciatic nerve. The length of the additional small
muscle was 85 mm with the broadest part of the muscle belly as 9 mm. The course
of the variant muscle, especially its tendinous part, might irritate the
sciatic nerve and cause piriformis syndrome and other sciatica-like symptoms.
The neurologists who diagnose piriformis syndrome and surgeons performing nerve
releasing surgery should be well aware of the described rare muscle
variation. 

Keywords

nerve compression syndrome; piriformis muscle; sciatic nerve; variation

References

• Clemente CD. Anatomy of the human body. 30th ed. Philadelphia (PA): Lea and Febiger; 1985. pp. 565–71.