Femoral Nerve Block anatomy

Relevant Anatomy

Femoral nerve (posterior divisions of L2-4) is formed in the psoas major muscle, runs between psoas and iliacus muscles and enters the thigh under the inguinal ligament lateral to the femoral artery, at which point it divides into multiple terminal branches (usually classified as anterior [mostly cutaneous] and posterior [mostly motor]).

Landmarks and Surrounding Structures

Important landmarks include the femoral crease, ASIS, pubic tubercle, femoral artery (palpable) and veins (not palpable), both located medially.

Cutaneous Innervation

The femoral nerve blocks the anterior thigh, as well as the medial lower leg (from the saphenous nerve). Note that it misses a portion of the medial thigh innervated by the obturator nerve (which also innervates the medially-located obturator externus, adductors [brevis, longus, and magnus], and gracilis muscles).

Muscular Innervation

Major muscles supplied by the femoral nerve include the anterior compartment muscles (quadriceps femoris, sartorius, and pectineus muscles), as well as the more proximal iliacus and psoas major muscles.

Distributions Missed

Medial thigh (obturator nerve)