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A three-headed piriformis muscle: an anatomical case study and narrative review of literature
Affiliations- Department of Anatomy, Jagiellonian University Medical College, Krakow, Poland
- Department of Normal and Clinical Anatomy, Institute of Medical Sciences, Medical College of Rzeszow University, Rzeszow, Poland
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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.
Keywords
piriformis muscle, piriformis syndrome, sciatic nerve, anatomy
About this articleTitle
A three-headed piriformis muscle: an anatomical case study and narrative review of literature
Journal
Issue
Article type
Case report
Pages
969-974
Published online
2022-12-22
Page views
1151
Article views/downloads
926
DOI
Pubmed
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
References (26)- Apaydin N, Tunstall R. Pelvic girdle and lower limb: overview and surface anatomy. In: Standring S (ed.) Gray’s Anatomy 41st ed. Elsevier Ltd., London 2016: 1323.
- Arifoglu Y, Sürücü HS, Sargon MF, et al. Double superior gemellus together with double piriformis and high division of the sciatic nerve. Surg Radiol Anat. 1997; 19(6): 407–408.
- Arora J, Mehta V, Kumar H, et al. A rare bimuscular conglomeration gluteopiriformis case report. Morphologie. 2010; 94(305): 40–43.
- Brenner E, Tripoli M, Scavo E, et al. Case report: absence of the right piriformis muscle in a woman. Surg Radiol Anat. 2019; 41(7): 845–848.
- Chang C, Jeno SH, Varacallo M. Anatomy, bony pelvis and lower limb, piriformis muscle. [Updated 2021 Oct 11]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing. https://www.ncbi.nlm.nih.gov/books/NBK519497/?fbclid=IwAR3hEMtHgQqHD_sB_SdNciw42dkO1ZJuObub9d8d8Me9eGMcXkJhq3hMMso (2022 Jan).
- Fishman LM, Schaefer MP. The piriformis syndrome is underdiagnosed. Muscle Nerve. 2003; 28(5): 646–649.
- Haładaj R, Pingot M, Polguj M, et al. Anthropometric study of the piriformis muscle and sciatic nerve: a morphological analysis in a Polish population. Med Sci Monit. 2015; 21: 3760–3768.
- Hopayian K, Danielyan A. Four symptoms define the piriformis syndrome: an updated systematic review of its clinical features. Eur J Orthop Surg Traumatol. 2018; 28(2): 155–164.
- Iwanaga J, Eid S, Simonds E, et al. The majority of piriformis muscles are innervated by the superior gluteal nerve. Clin Anat. 2019; 32(2): 282–286.
- Iwanaga J, Singh V, Takeda S, et al. Acknowledging the use of human cadaveric tissues in research papers: Recommendations from anatomical journal editors. Clin Anat. 2021; 34(1): 2–4.
- Kurtoglu Z, Aktekin M, Uluutku MH. Branching patterns of the common and superficial fibular nerves in fetus. Clin Anat. 2006; 19(7): 621–626.
- Lewis S, Jurak J, Lee C, et al. Anatomical variations of the sciatic nerve, in relation to the piriformis muscle. Transl Res Anat. 2016; 5: 15–19.
- McLawhorn AS, Christ AB, Morgenstern R, et al. Prospective evaluation of the posterior tissue envelope and anterior capsule after anterior total hip arthroplasty. J Arthroplasty. 2020; 35(3): 767–773.
- Naito M, Suzuki R, Abe H, et al. Fetal development of the human obturator internus muscle with special reference to the tendon and pulley. Anat Rec (Hoboken). 2015; 298(7): 1282–1293.
- Natsis K, Totlis T, Konstantinidis GA, et al. Anatomical variations between the sciatic nerve and the piriformis muscle: a contribution to surgical anatomy in piriformis syndrome. Surg Radiol Anat. 2014; 36(3): 273–280.
- Niikura H, Jin ZWu, Cho BH, et al. Human fetal anatomy of the coccygeal attachments of the levator ani muscle. Clin Anat. 2010; 23(5): 566–574.
- Ozisik PA, Toru M, Denk CC, et al. CT-guided piriformis muscle injection for the treatment of piriformis syndrome. Turk Neurosurg. 2014; 24(4): 471–477.
- Robinson DR. Pyriformis syndrome in relation to sciatic pain. Am J Surg. 1947; 73(3): 355–358.
- Santamato A, Micello MF, Valeno G, et al. Ultrasound-Guided injection of botulinum toxin type a for piriformis muscle syndrome: a case report and review of the literature. Toxins (Basel). 2015; 7(8): 3045–3056.
- Smoll NR. Variations of the piriformis and sciatic nerve with clinical consequence: a review. Clin Anat. 2010; 23(1): 8–17.
- Sulak O, Sakalli B, Ozguner G, et al. Anatomical relation between sciatic nerve and piriformis muscle and its bifurcation level during fetal period in human. Surg Radiol Anat. 2014; 36(3): 265–272.
- Thompson G, Visagie R. Type II sciatic nerve variant: an unexpected interventional hazard. Skeletal Radiol. 2017; 46(10): 1453–1458.
- Tomaszewski KA, Graves MJ, Henry BM, et al. Surgical anatomy of the sciatic nerve: A meta-analysis. J Orthop Res. 2016; 34(10): 1820–1827.
- Tubbs R, Barton J, Watson C, et al. A novel method for sciatic nerve decompression: Cadaveric feasibility study with potential application to patients with piriformis syndrome. Transl Res Anat. 2015; 1: 40–43.
- Wun-Schen C. Bipartite piriformis muscle: an unusual cause of sciatic nerve entrapment. Pain. 1994; 58(2): 269–272.
- Żytkowski A, Tubbs R, Iwanaga J, et al. Anatomical normality and variability: Historical perspective and methodological considerations. Transl Res Anat. 2021; 23: 100105.
