Which nerve lies outside the femoral sheath and enters the femoral triangle lateral to the femoral artery?

Explanation

## Femoral Sheath and Neurovascular Contents The femoral sheath is a downward continuation of the fascia transversalis and iliopectineal fascia, forming a tubular compartment below the inguinal ligament. ### Contents of the Femoral Sheath (Medial to Lateral) | Structure | Location | Compartment | | --- | --- | --- | | **Femoral canal** | Medial | Contains lymph nodes (node of Cloquet) | | **Femoral vein** | Middle | Vascular compartment | | **Femoral artery** | Lateral | Vascular compartment | | **Femoral nerve** | **Outside sheath** | **Lateral to artery** | **Key Point:** The femoral nerve is the **only major neurovascular structure that lies OUTSIDE the femoral sheath**. It enters the triangle lateral to the femoral artery, between the psoas and iliacus muscles. **Mnemonic:** **VAN** (Vein-Artery-Nerve) describes the medial-to-lateral order, but this applies only to structures *within* the sheath. The femoral nerve is **lateral to this arrangement**, outside the sheath. **High-Yield:** The femoral canal (medial compartment of the sheath) is clinically significant because it is the site of femoral hernia formation. The saphenous nerve branches from the femoral nerve and runs medially with the saphenous vein. **Clinical Pearl:** Femoral nerve block is performed lateral to the femoral artery at the groin, targeting the nerve as it lies in the groove between psoas and iliacus.