82 - Laterality in Anatomical Variations: A Cadaveric Study Investigating Sciatic Nerve and Piriformis Muscle Relationships

Poster Board Number: 82
There are separate poster presentation times for odd and even posters.
Odd poster #s – first hour
Even poster #s – second hour

Co-authors:

Johnni Morris - DPT student, Physical Therapy Department, Bellarmine University; Joseph Naville - DPT student, Physical Therapy Department, Bellarmine University; Zach Pollard - DPT student, Physical Therapy Department, Bellarmine University

Abstract Body : Introduction and Objective: The sciatic nerve is the largest and widest nerve in the body derived from ventral rami of L4-S3 spinal nerves. It travels from the lower back and pelvis to the gluteal region, passes inferior to the piriformis muscle to continue through the posterior thigh. The sciatic nerve innervates the posterior thigh muscles, and its terminal branches provide motor and sensory innervation to the majority of the leg and foot. Several studies have documented anatomical variations between the piriformis muscle and the sciatic nerve. This study aimed to examine the anatomical relationships between the sciatic nerve and piriformis muscle in dissected cadavers, identifying and describing any anatomical variations and exploring their laterality. Materials and Methods: Over a period of four years, sixty-six cadavers (32 Males and 34 Females) were carefully dissected and examined for anatomical variations between the sciatic nerve and the piriformis muscle. We categorize the different types of anatomical relationship by following the classification system described by Beaton and Anson. Results: Of the sixty-six cadavers dissected, 57 (86.36%) had a normal Type-a presentation: undivided sciatic nerve below the undivided piriformis muscle. Eight cadavers (12.12%) had Type-b presentation: common fibular division of sciatic nerve pierces and divides the piriformis muscle while tibial division travels inferior to the piriformis muscle. One cadaver (1.52%) demonstrated a Type-c variation: common fibular division travels superior to the piriformis muscle and tibial division passes inferior to the piriformis. When examining for laterality, five of the nine (55.56%) cadavers with type-b or type-c presentation were bilateral and identical. Conclusions: This study provided additional information on the prevalence of bilateral and unilateral presentation of anatomical variations between the sciatic nerve and piriformis muscle. These variations could result in unilateral or bilateral symptoms of neuropathy or muscle weakness in the lower extremities. Awareness of these variations and their laterality occurrence could enhance treatments associated with the affected regions.