When performing a femoral nerve block (3-in-1 block), the femoral artery is palpated just below the inguinal ligament. The femoral nerve lies at which position relative to the femoral artery within the femoral triangle?

• A Lateral to the femoral artery, outside the femoral sheath ✓
• B Medial to the femoral artery, inside the femoral sheath
• C Posterior to the femoral artery, inside the femoral sheath
• D Lateral to the femoral artery, inside the femoral sheath in the lateral compartment

Explanation

The femoral sheath is a prolongation of the transversalis and iliacus fasciae and encloses the femoral artery, vein, and the femoral canal (from lateral to medial: artery, vein, canal). The femoral nerve lies immediately lateral to the femoral sheath but NOT within it — it descends in the groove between the iliacus and psoas major muscles and is separated from the femoral vessels by the iliopectineal fascia. For femoral nerve block the needle is inserted 1–2 cm lateral to the femoral artery, below the inguinal ligament, outside the sheath. Inadvertent medial placement risks femoral vessel puncture.

Reference: BD Chaurasia's Human Anatomy, 8th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.