Anatomical variations between the sciatic nerve and the piriformis muscle: a contribution to surgical anatomy in piriformis syndrome

Abstract

Context: Piriform muscle syndrome can be caused by abnormal passage of the sciatic nerve or one of its parts through the belly of the piriform muscle. Objective: To analyze the anatomical and measurement relationships between the piriform muscle and the sciatic nerve in order to contribute towards better anatomoclinical understanding of the gluteal region. Method: Twenty adult cadavers of both sexes were used. The sciatic nerve and piriform muscle were dissected, measured and photodocumented. Results: The sciatic nerve was seen to be a single trunk passing through the lower margin of the piriform muscle in 85% of the 40 gluteal regions, and 15% showed bilateral variation characterized by the passage of the common fibular nerve through the piriform muscle. The data obtained did not show any statistically significant differences.

An unorthodox innervation of the gluteus maximus muscle and other associated variations: A case report

“…8 In the present case high division of the sciatic nerve was observed with the common peroneal nerve passing between the two heads of the piriformis and tibial nerve passing inferior to it. This variant relationship between the branches of the sciatic nerve and the piriformis muscle was previously reported by Natsis et al 9 According to them, in 4.1 per cent of the cases, the common peroneal nerve passed between the piriformis and the tibial nerve inferior to it. This could be associated with piriformis syndrome, and therefore identification of the additional bellies of the piriformis is necessary for adequate sciatic nerve decompression in cases where compression of the sciatic nerve in the gluteal region is diagnosed.…”

“…This could be associated with piriformis syndrome, and therefore identification of the additional bellies of the piriformis is necessary for adequate sciatic nerve decompression in cases where compression of the sciatic nerve in the gluteal region is diagnosed. 9 The inferior gluteal nerve normally arises inferior to the piriformis and generally ends by supplying the gluteus maximus muscle and has no cutaneous branches; 1 however, this nerve may also show variations. 10,11 Authors in the past have reported a case of high division of the sciatic nerve with an anomalous double root of the inferior gluteal nerve emerging along both the upper and lower borders of the piriformis muscle to form the inferior gluteal nerve to supply the gluteus maximus muscle.…”

The sciatic nerve in human cadavers — high division or low formation?

“…Similar variant was reported in one case by Arifoğlu et al [1], and by Kırıcı and Ozan [8]. Natsis et al [13] dissected Caucasian cadavers (294 limbs) and only in 12 limbs (4.1%) he found the CFN passed through and the TN below a double piriformis, while Güvençer et al [7], found this variation in 14% of their cases. While two specimens (1 and 3) from our study appeared to be Beaton and Anson type 3 variation (Fig.…”

Comparing the Efficacy of 2 Techniques for Piriformis Muscle Injection Proceed With Caution

“…Furthermore, it is likely that reliable results are dependent on dispersion of the injectate as the idea that sciatic nerve irritation in the region is solely due to inflammation of a single muscle (piriformis) would seem unlikely in light of anatomic variation of the sciatic nerve in relation to the gluteal, piriformis, superior and inferior gemellus, obturator internus, and quadratus femoris muscles. [4][5][6][7] The additional concern raised by Dr Morrigl and colleagues is understood, given the unique ultrasound view of the piriformis and related structures that was published. For clarification, we would like to refer readers to the response we submitted separately in response to Dr Bhatia's letter to the editor.…”