title: Anatomical variations between the sciatic nerve and the piriformis muscle: a contribution to surgical anatomy in piriformis syndrome.
abstract: OBJECTIVE
  To detect the variable relationship between sciatic nerve and piriformis muscle and make surgeons aware of certain anatomical features of each variation that may be useful for the surgical treatment of the piriformis syndrome.
  
  
  METHODS
  The gluteal region of 147 Caucasian cadavers (294 limbs) was dissected. The anatomical relationship between the sciatic nerve and the piriformis muscle was recorded and classified according to the Beaton and Anson classification. The literature was reviewed to summarize the incidence of each variation.
  
  
  RESULTS
  The sciatic nerve and piriformis muscle relationship followed the typical anatomical pattern in 275 limbs (93.6 %). In 12 limbs (4.1 %) the common peroneal nerve passed through and the tibial nerve below a double piriformis. In one limb (0.3 %) the common peroneal nerve coursed superior and the tibial nerve below the piriformis. In one limb (0.3 %) both nerves penetrated the piriformis. In one limb (0.3 %) both nerves passed above the piriformis. Four limbs (1.4 %) presented non-classified anatomical variations. When a double piriformis muscle was present, two different arrangements of the two heads were observed.
  
  
  CONCLUSIONS
  Anatomical variations of the sciatic nerve around the piriformis muscle were present in 6.4 % of the limbs examined. When dissection of the entire piriformis is necessary for adequate sciatic nerve decompression, the surgeon should explore for the possible existence of a second tendon, which may be found either inferior or deep to the first one. Some rare, unclassified variations of the sciatic nerve should be expected during surgical intervention of the region.
authors.affiliation: Laboratory of Anatomy, Medical School, Aristotle University of Thessaloniki, P.O. Box: 300, Postal Code: 54124, Thessaloniki, Macedonia, Greece, natsis@med.auth.gr.
authors.forename: Konstantinos
authors.initials: K
authors.lastname: Natsis
authors.forename: Trifon
authors.initials: T
authors.lastname: Totlis
authors.forename: George A
authors.initials: GA
authors.lastname: Konstantinidis
authors.forename: George
authors.initials: G
authors.lastname: Paraskevas
authors.forename: Maria
authors.initials: M
authors.lastname: Piagkou
authors.forename: Juergen
authors.initials: J
authors.lastname: Koebke
mesh_terms: D002102:Cadaver; D006801:Humans; D018482:Muscle, Skeletal / Q000033:anatomy & histology*; D010543:Peroneal Nerve / Q000033:anatomy & histology; D055958:Piriformis Muscle Syndrome / Q000473:pathology* / Q000601:surgery; D012584:Sciatic Nerve / Q000033:anatomy & histology*; D013979:Tibial Nerve / Q000033:anatomy & histology
references.citation: Surg Radiol Anat. 2007 Feb;29(1):37-45
references.pmid: 17216293
references.citation: Clin Anat. 2010 Jan;23(1):8-17
references.pmid: 19998490
references.citation: Acta Chir Orthop Traumatol Cech. 1998;65(6):336-9
references.pmid: 20492810
references.citation: Kaibogaku Zasshi. 1992 Dec;67(6):691-724
references.pmid: 1296428
references.citation: Surg Radiol Anat. 2008 Aug;30(6):467-74
references.pmid: 18458807
references.citation: Okajimas Folia Anat Jpn. 1999 Dec;76(5):273-6
references.pmid: 10693331
references.citation: West J Med. 1976 Jun;124(6):435-9
references.pmid: 132772
references.citation: Surg Radiol Anat. 2012 Sep;34(7):671
references.pmid: 22572807
references.citation: Surg Radiol Anat. 2006 Mar;28(1):88-91
references.pmid: 16311716
references.citation: Surg Radiol Anat. 1997;19(6):407-8
references.pmid: 9479716
references.citation: Spine (Phila Pa 1976). 2006 Aug 15;31(18):E664-6
references.pmid: 16915082
references.citation: Postgrad Med. 1983 Aug;74(2):69-72
references.pmid: 6878094
references.citation: Turk Neurosurg. 2009 Apr;19(2):139-44
references.pmid: 19431123
references.citation: Muscle Nerve. 2003 Nov;28(5):646-9
references.pmid: 14571472
references.citation: Rev Chir Orthop Reparatrice Appar Mot. 1996;82(7):647-57
references.pmid: 9091984
references.citation: Orthop Clin North Am. 2004 Jan;35(1):65-71
references.pmid: 15062719
references.citation: Taiwan Yi Xue Hui Za Zhi. 1974 Feb;73(2):75-80
references.pmid: 4527572
references.citation: Surg Radiol Anat. 2012 Aug;34(6):479-86
references.pmid: 22327640
references.citation: Pain. 1991 Dec;47(3):345-352
references.pmid: 1784505
references.citation: Kaibogaku Zasshi. 1994 Jun;69(3):281-305
references.pmid: 8091946
references.citation: J Formos Med Assoc. 1992 Jun;91(6):647-50
references.pmid: 1358356
references.citation: Vojnosanit Pregl. 2005 Jan;62(1):45-9
references.pmid: 15715349
references.citation: Anesthesiology. 2003 Jun;98(6):1442-8
references.pmid: 12766656
references.citation: Eur Spine J. 2010 Dec;19(12):2095-109
references.pmid: 20596735
references.citation: Eur J Morphol. 2003 Feb;41(1):41-2
references.pmid: 15121548
references.citation: Acta Anat (Basel). 1979;105(2):181-7
references.pmid: 532546
references.citation: Folia Morphol (Warsz). 1972;31(4):507-13
references.pmid: 4539117
references.citation: J Neurosurg Spine. 2005 Feb;2(2):99-115
references.pmid: 15739520
references.citation: J Orthop Surg Res. 2010 Jan 21;5:3
references.pmid: 20180984
references.citation: J Anat Physiol. 1896 Oct;31(Pt 1):31-44
references.pmid: 17232229
references.citation: Arch Phys Med Rehabil. 2002 Mar;83(3):295-301
references.pmid: 11887107