What is the relationship between the sartorius muscle and the saphenous nerve?

Anatomical Relationship Between the Sartorius Muscle and Saphenous Nerve

The sartorius muscle serves as an important anatomical landmark for the saphenous nerve, with the nerve typically coursing alongside the muscle and exiting the adductor canal to travel between the sartorius and gracilis muscles before becoming cutaneous. 1

Anatomical Course and Relationship

• The saphenous nerve exits the adductor canal at approximately 10.25 cm (range 7.0-11.5 cm) proximal to the patella, where it maintains a close relationship with the sartorius muscle 2
• After exiting the adductor canal, the saphenous nerve travels between the sartorius and gracilis tendons before piercing the fascia lata to become cutaneous 3
• The nerve typically emerges near the anterior border of the sartorius muscle in approximately 68.7% of cases 4
• At the level of the knee joint line, the saphenous nerve is located at an average distance of 16.0-16.5 mm from the anterior border of the sartorius muscle 5

Clinical Significance in Surgical Procedures

• During modified inguinal lymphadenectomy procedures, the sartorius muscle serves as an important lateral boundary, with preservation of the saphenous vein and elimination of the need to transpose the sartorius muscle 1
• The inguinofemoral nodal clinical target volume during radiation therapy extends laterally from the inguinofemoral vessels to the medial border of the sartorius muscle 1
• During video endoscopic inguinal lymphadenectomy (VEIL), the sartorius muscle forms the lateral boundary of the dissection, with the adductor longus muscle forming the medial boundary 1

Nerve Branches and Variations

• The saphenous nerve bifurcates into the infrapatellar branch and sartorial branch, with this bifurcation occurring at its closest approximation to the saphenous branch of the descending genicular artery 2
• The infrapatellar branch of the saphenous nerve can become entrapped behind the sartorius tendon against the prominent edge of the medial femoral condyle, causing localized pain and tenderness 6
• In rare cases, the saphenous nerve may provide an unusual motor branch to the sartorius muscle, typically in the lower third of the thigh after exiting the adductor canal 3
• The sartorial branch of the saphenous nerve is rarely located posterior or lateral to the semitendinosus muscle, and is anterior to the sartorius in only 3% of knees 5

Clinical Implications

• The close relationship between the sartorius muscle and saphenous nerve creates potential for nerve injury during knee surgeries, particularly arthroscopic meniscal repairs 5
• The saphenous nerve is at risk during adductor canal blocks, arthroscopy, and other knee surgeries due to its variable course in relation to the sartorius muscle 3
• Understanding the anatomical relationship is crucial for surgical approaches to the posteromedial corner of the knee to minimize the risk of nerve injury 5
• The distance between the medial margin of the patella and the nerve trunk typically ranges between 4-7 mm, creating a high-risk zone for nerve damage during medial knee incisions 4