Z. Aslı AKTAN İKİZ, OKAN BİLGE, HÜLYA ÜÇERLER, SERVET ÇELİK, ERENGÜL BODUÇ

Variant anatomy of sciatic nerve and their clinical implications

Aim: The aim of present study was to demonstrate the variations of piriformis muscle, sciatic nerve and its branches and discuss their clinical importance. Materials and Methods: Fifty-two gluteal and lower limb regions of 26 formalin fixed male cadavers were evaluated in Ege University Faculty of Medicine, Department of Anatomy. The anatomical relationship between the sciatic nerve and the piriformis muscle, and division level of sciatic nerve in thigh was recorded. Results: The sciatic nerve exited the pelvis as a single branch through the infrapiriform foramen with no variation in 84.62% of the lower limbs. The division variations of sciatic nerve were determined in 23.08%. In 8 of 12 high divisions were observed in gluteal regions (15.38%). The common peroneal nerve and the tibial nerve entered deep gluteal region via the greater sciatic foramen below piriformis muscle separately in four lower limbs (7.69%). Two separate nerve divisions passed above and through (or below) the piriformis muscle and then combined together to form common peroneal nerve while tibial nerve passing below the piriformis muscle in 4 lower limbs (7.69%). In 2 of 12, high division occurred in the 1/3 upper portion of the thigh unilaterally (3.85%). The division of sciatic nerve in the popliteal fossa was seen in two lower limbs (3.85%). Conclusion: The clinical importance of the sciatic nerve around the piriformis muscle or in the thigh was discussed for piriformis syndrome, palsy after total hip arthroplasty, intramuscular injections in gluteal region and failed popliteal nerve block.

Siyatik sinirin varyasyon anatomisi ve klinik yansımaları

Amaç: Çalışmanın amacı musculus piriformis, siyatik sinir ve dallarının varyasyonlarını göstermek ve klinik önemini tartışmaktır. Gereç ve Yöntem: Ege Üniversitesi Tıp Fakültesi, Anatomi Anabilim Dalı’nda formalin ile fikse edilmiş 26 erkek kadavraya ait 52 adet gluteal bölge ve alt ekstremite değerlendirildi. Siyatik sinir ve musculus piriformis arasındaki anatomik ilişki ile uylukta siyatik sinirin dallanma seviyesi kaydedildi. Bulgular: Alt ekstremitelerin %84.62’sinde siyatik sinir pelvisten tek dal halinde, varyasyonsuz olarak çıktı. Siyatik sinirin dallanma varyasyonu %23.08 olarak tespit edildi. On iki adet olarak bulunan yüksekten ayrılmanın 8’i gluteal bölgede idi (%15.38). Dört alt ekstremitede (%7.69) nervus peroneus communis ve nervus tibialis derin gluteal bölgeye foramen ischiadicum majus yolu ile musculus piriformis’in altından ayrı ayrı girdi. Dört alt ekstremitede ise (%7.69) iki ayrı dal musculus piriformis’in üzerinden, içinden (ya da altından) geçti ve nervus tibialis musculus piriformis’in altından geçerken bu iki dal da nervus peroneus communis’i oluşturmak üzere daha sonra birleşti. On iki örneğin ikisinde, yüksekte ayrılma unilateral olarak uyluğun 1/3 üst bölümünde izlendi. Siyatik sinirin fossa poplitea’da dallarına ayrılması da iki alt ekstremitede görüldü (%3.85). Sonuç: Siyatik sinirin musculus piriformis çevresindeki veya uyluktaki varyasyonları; piriformis sendromu, total kalça protezi sonrası ortaya çıkan paralizi, gluteal bölgeye uygulanan intramusküler enjeksiyonlar ve başarısız popliteal sinir bloğu yönü ile tartışıldı.

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