Adductor Canal

Introduction

Introduction to the Adductor Canal

The adductor canal (Hunter's canal) is an aponeurotic fascial tunnel located in the middle third of the thigh. It provides a conduit for the femoral artery, femoral vein, and the saphenous nerve (and nerve to vastus medialis) as they travel from the apex of the femoral triangle to the adductor hiatus in the adductor magnus muscle. The canal is clinically significant as the site of adductor canal blocks for knee surgery and as a region where the femoral vessels are vulnerable to traumatic injury and peripheral arterial disease.

Study

1. Boundaries of the Adductor Canal

The adductor canal is triangular in cross‑section and approximately 15 cm long. It is bounded: anterolaterally by the vastus medialis muscle; posteriorly (or floor) by the adductor longus proximally and the adductor magnus distally; medially (or roof) by the sartorius muscle and the subsartorial fascia (the deep fascia that connects the sartorius to the vastus medialis and the adductor muscles).

The canal begins at the apex of the femoral triangle, where the sartorius crosses over the femoral vessels, and ends at the adductor hiatus, an opening in the tendon of adductor magnus, where the femoral vessels pass posteriorly to become the popliteal vessels.

2. Contents of the Adductor Canal

The adductor canal contains, from anterior to posterior: the femoral artery, the femoral vein (posterolateral to the artery in the distal part of the canal), the saphenous nerve (initially lateral to the artery, then crossing anterior to the artery to lie medially), and the nerve to vastus medialis (a branch of the femoral nerve). The saphenous nerve is the terminal sensory branch of the femoral nerve. The nerve to vastus medialis provides motor innervation to the vastus medialis muscle and contains proprioceptive fibres from the knee joint.

The femoral artery gives off the descending genicular artery within the adductor canal, which contributes to the genicular anastomosis of the knee.

3. Relations

Superficially, the canal is covered by the sartorius muscle. The great saphenous vein, accompanied by the saphenous nerve, runs superficial to the sartorius in the subsartorial plexus but is not within the canal. Deep to the canal lie the adductor longus and adductor magnus muscles and the medial intermuscular septum.

4. Clinical Relevance

The adductor canal block is a regional anaesthetic technique that targets the saphenous nerve (and sometimes the nerve to vastus medialis) within the canal to provide sensory anaesthesia to the anterior knee and medial leg without causing significant quadriceps weakness. This is advantageous for postoperative analgesia after knee surgery.

The femoral artery is relatively fixed within the canal and is vulnerable to injury in distal femoral fractures. Peripheral arterial disease frequently affects the femoral artery within the canal. The saphenous nerve may be entrapped at its exit from the subsartorial fascia (saphenous nerve entrapment syndrome). The adductor canal is also used as a surgical approach for exposure of the distal femoral artery.

Summary

Summary of the Adductor Canal

The adductor canal is a fascial tunnel in the middle third of the thigh, bounded by the vastus medialis, adductor longus/magnus, and sartorius. It contains the femoral artery, femoral vein, saphenous nerve, and nerve to vastus medialis. It serves as a landmark for regional anaesthesia (adductor canal block) and is clinically relevant for vascular access, peripheral arterial disease, and nerve entrapment.