open access

Vol 82, No 4 (2023)
Case report
Submitted: 2022-10-04
Accepted: 2022-11-29
Published online: 2022-12-22
Get Citation

A three-headed piriformis muscle: an anatomical case study and narrative review of literature

T. Kozioł1, W. Chaba1, P. Janda1, K. Ochwat1, P. Pękala1, K. Balawender2, J. A. Walocha1, M. P. Zarzecki1
·
Pubmed: 36573364
·
Folia Morphol 2023;82(4):969-974.
Affiliations
  1. Department of Anatomy, Jagiellonian University Medical College, Krakow, Poland
  2. Department of Normal and Clinical Anatomy, Institute of Medical Sciences, Medical College of Rzeszow University, Rzeszow, Poland

open access

Vol 82, No 4 (2023)
CASE REPORTS
Submitted: 2022-10-04
Accepted: 2022-11-29
Published online: 2022-12-22

Abstract

The piriformis muscle (PM) is found in the gluteal region, exiting the pelvis
through the greater sciatic foramen and dividing it into the suprapiriform and
infrapiriform foramina. The piriformis works as part of the hip external rotator
muscle group, and is responsible for rotation of the femur upon hip extension
and abduction of the femur during flexion of the hip joint. The aim of the present
report is to describe a very rare case of the primary three-headed PM. To the
best knowledge of the authors, the said variant has not yet been described in
the existing literature.
The 71-year-old male formalin-fixed cadaver was subjected to routine dissection.
After careful removal of the connecting tissue, three separate, primary heads of
the PM were identified. The lower head of the PM arose from the middle part
of the sacral bone; 87.56 mm long and 9.73 mm wide. The medial head was
attached to the internal part of the posterior inferior iliac spine; 121.6 mm long
and 20.97 mm wide. The upper head was attached to the external part of the
posterior inferior iliac spine; 78.89 mm long and 23.94 mm wide. All heads
converged into a common tendon which inserted onto the greater trochanter.
The clinical importance of this work comes down to the fact that the aberrant PM
may be the reason behind the piriformis syndrome and its associated symptoms.
Moreover, knowledge regarding the variant anatomy of the PM is of immense
importance to, e.g. anaesthesiologists performing computed tomography- or
ultrasound-guided sciatic nerve injection for local anaesthesia, radiologists interpreting
imaging studies, and surgeons, especially during posterior approaches to
the hip and pelvis.

Abstract

The piriformis muscle (PM) is found in the gluteal region, exiting the pelvis
through the greater sciatic foramen and dividing it into the suprapiriform and
infrapiriform foramina. The piriformis works as part of the hip external rotator
muscle group, and is responsible for rotation of the femur upon hip extension
and abduction of the femur during flexion of the hip joint. The aim of the present
report is to describe a very rare case of the primary three-headed PM. To the
best knowledge of the authors, the said variant has not yet been described in
the existing literature.
The 71-year-old male formalin-fixed cadaver was subjected to routine dissection.
After careful removal of the connecting tissue, three separate, primary heads of
the PM were identified. The lower head of the PM arose from the middle part
of the sacral bone; 87.56 mm long and 9.73 mm wide. The medial head was
attached to the internal part of the posterior inferior iliac spine; 121.6 mm long
and 20.97 mm wide. The upper head was attached to the external part of the
posterior inferior iliac spine; 78.89 mm long and 23.94 mm wide. All heads
converged into a common tendon which inserted onto the greater trochanter.
The clinical importance of this work comes down to the fact that the aberrant PM
may be the reason behind the piriformis syndrome and its associated symptoms.
Moreover, knowledge regarding the variant anatomy of the PM is of immense
importance to, e.g. anaesthesiologists performing computed tomography- or
ultrasound-guided sciatic nerve injection for local anaesthesia, radiologists interpreting
imaging studies, and surgeons, especially during posterior approaches to
the hip and pelvis.

Get Citation

Keywords

piriformis muscle, piriformis syndrome, sciatic nerve, anatomy

About this article
Title

A three-headed piriformis muscle: an anatomical case study and narrative review of literature

Journal

Folia Morphologica

Issue

Vol 82, No 4 (2023)

Article type

Case report

Pages

969-974

Published online

2022-12-22

Page views

1124

Article views/downloads

874

DOI

10.5603/FM.a2022.0108

Pubmed

36573364

Bibliographic record

Folia Morphol 2023;82(4):969-974.

Keywords

piriformis muscle
piriformis syndrome
sciatic nerve
anatomy

Authors

T. Kozioł
W. Chaba
P. Janda
K. Ochwat
P. Pękala
K. Balawender
J. A. Walocha
M. P. Zarzecki

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