A cadaveric study of the anatomical variations of the lumbar plexus with clinical implications

Introduction The main objective was to study the normal and abnormal lumbar plexus. Material and methods We analyzed 131 lumbar plexuses from 68 embalmed cadavers at the Cadaveric Surgical Training Center, Faculty of Medicine, Chiang Mai University in the period between April 2012 and June 2013. Morphometric measurements were taken. Results The lumbar plexus was located within psoas major muscle (100.0%). The iliohypogastric nerve originated from the ventral rami of L₁ (96.5%) followed by the ilioinguinal nerve (90.1%). The genitofemoral nerves originated from the ventral rami of L₁ and L₂ (98.5%). The lateral femoral cutaneous nerves (LFCN) originated from the ventral rami of L₂ and L₃ (84.0%). The femoral and obturator nerves originated from ventral rami of L₂–L₃–L₄ (100.0%). The distance between the origin of LFCN to L₃ transverse process was at an average 1.96 ± 0.67 cm. The distance from nerve to L₄ transverse process was above L₃ and between L₃ and L₄ transverse process at an average 2.8 ± 1.63 cm. The distance between femoral nerve to L₃ and L₄ transverse process was inferior to L₄ transverse process at an average of 5.13 ± 2.18 cm and 2.53 ± 2.26 cm, respectively. The distance between obturator nerve to L₃ and L₄ transverse process was found inferior to L₄ transverse process at an average 5.42 ± 1.73 cm and 2.75 ± 1.75 cm, respectively. Discussion The knowledge of anatomical variations of LP may be important for administration of local anaesthetic agents and avoid any inadvertent injuries.