The femoral branch of the genitofemoral nerve (FBFGN) passes under the inguinal ligament together with the femoral vessels via the lacuna vasorum which is separated from the the lacuna musculorum by the fibrous iliopectineal arch
Place the patient supine
Place the high-frequency probe in the inguinal crease and identify the pulsating femoral artery
Identify the femoral branch of the genitofemoral nerve just lateral to the femoral artery (see next page)
Insert the needle in-plane from the lateral end of the probe and advance the needle tip until it is placed in touch with the femoral branch of the genitofemoral nerve
Inject 5 mL of local anaesthetic perineurally
The genitofemoral nerve pierces the psoas major and descends on its anterior surface. It splits into two branches – a genital and a femoral branch
The femoral branch of the genitofemoral nerve is just lateral to the femoral artery through the lacuna vasorum which is medial to the iliopectineal arch. It innervates the skin just distal to the inguinal ligament
The genital branch of the genitofemoral nerve follow the spermatic cord in males and innervates the scrotal skin and supply motor branches to the cremaster muscle
In females it runs via the inguinal canal together with the round ligament of the uterus; it innervates the labia majora
Femoral branch of the genitofemoral nerve:
– the skin distal to the inguinal ligament
Taha AM: Ultrasound-guided obturator nerve block: A proximal interfascial technique. Anesth Analg 114:236-39 (2012)
Kendir S, Akkaya T, Comert A, Sayin M, Tatlisumak E, Elhan A, Tekmedir I: The location of the obturator nerve: A three-dimensional description of the obturator canal. Surg Radiol Anat 30:495-501 (2008)
The anterior branch of the obturator nerve descends in the fascial plane between the adductor longus and brevis muscles
The posterior branch of the obturator nerve pierces the external obturator muscle and descends in the fascial plane between the adductor brevis muscle and the adductor magnus muscle
Place the patient supine
Place the high-frequency linear probe in the inguinal crease
Identify the pulsating femoral artery. Slide the probe medially until you identify the adductor muscles (see next page)
Blockade of the anterior and posterior branches separately: Insert the needle from the lateral end of the probe and deposit 10 mL of local anaesthetic in the fascial plane between the adductor longus and brevis as well as in the fascial plane between the adductor brevis and magnus
Blockade of the common trunk of the obturator nerve: Tilt the tail of the probe down while you follow the pectineus muscle until you visualize the fascial plane between the pectineus and obturator externus. Insert the needle from the lateral end of the probe and deposit 10 mL of local anaesthetic in this fascial plane
The needle tip is first inserted into the fascial plane between the adductor longus and brevis and then into the fascial plane between the adductor brevis and magnus
10 mL of local anaesthetic is injected into each fascial plane
Often the target obturator nerve branches are not visible – especially before injection of local anaesthetic
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)
Bodner G, Bernathova M, Galiano K, Putz D, Martinoli C: Ultrasound of the lateral femoral cutaneous nerve: Normal findings in a cadaver and in volunteers. Reg Anesth Pain Med 34(3): 265-68 (2009)
