Fig 4. Transverse sonogram of the inner aspect of the proximal thigh 2 cm proximal to the inguinal crease showing the pectineus and obturator externus muscles and the obturator nerve. (B) Annotated structures identified in (A). Abbreviations: P m., pectineus muscle; OE m., obturator externus muscle. Yellow: obturator nerve within the intermuscular aponeurotic septum.