The needle tip is advanced to the fascial plane between the pectineus and obturator externus at the level of the superior pubic ramus
The needle tip is aimed at the lateral corner of this fascial plane
15 mL of local anaesthetic is injected and intended to spread in the entire fascial plane between the two muscles in order to cover the common obturator and/or the anterior and posterior branches of the obturator nerve before they leave this plane
Ref: Taha (2012)
Pectineus (red asterix), obturator externus (cyan asterix), adductor brevis (green asterix), superior pubic ramus (yellow arrow), needle (red), local anaesthetic (yellow shadow), L = lateral, M = medial