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Anatomic considerations and the relationship between the piriformis muscle and the sciatic nerve
Mustafa Güvençer1, Pinar Akyer, Cihan Iyem
1Department of Anatomy, School of Medicine, Dokuz Eylül University, 35340 Balçova/Izmir, Turkey. mustafa.guvencer@deu.edu.tr
Surgical and Radiologic Anatomy : SRA
|May 7, 2008
Summary
Piriformis syndrome, a cause of sciatica, involves sciatic nerve (SN) compression by the piriformis muscle (PM). This study found the SN is prone to entrapment during a stretch test due to anatomical changes, confirming diagnostic needs.
Area of Science:
- Anatomy
- Orthopedics
- Neurology
Background:
- Piriformis syndrome is a non-discogenic cause of sciatica, stemming from sciatic nerve (SN) compression by the piriformis muscle (PM).
- Increased pain during piriformis stretch tests necessitates understanding anatomical changes in the SN and PM during these positions.
Purpose of the Study:
- To morphometrically examine the anatomical relationship between the sciatic nerve and piriformis muscle in neutral and piriformis stretch test positions.
Main Methods:
- Twenty lower limbs from ten adult cadavers were dissected to visualize the SN and PM.
- Measurements were taken in neutral and test positions (hip: 30° adduction, 60° flexion, 10° medial rotation) relative to bony landmarks.
Main Results:
- The sciatic nerve's diameter decreased significantly at the lesser trochanter level in the test position.
- Morphometric analysis revealed the infrapiriforme foramen narrows, and the SN moves closer to the ischial spine during the stretch test.
Conclusions:
- The sciatic nerve is susceptible to entrapment in the piriformis stretch test position due to observed anatomical changes.
- Dynamic MRI and MR neurography are recommended for diagnosing piriformis syndrome, considering the dynamic nature of SN compression.
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