Saphenous Nerve
The sensory nerve running from the anterior-medial knee down the medial aspect of the tibia is the saphenous nerve, specifically its infrapatellar branch.
Anatomical Course
The saphenous nerve is a terminal branch of the femoral nerve that provides sensory innervation to the medial lower extremity 1. The nerve has two major divisions that are clinically relevant:
- Sartorial branch: Runs along the medial aspect of the leg
- Infrapatellar branch: Exits the sartorius muscle to become subcutaneous, providing sensation to the anterior-medial knee region 2
The infrapatellar branch specifically innervates the skin over the anterior-medial knee and continues down along the medial tibia 2, 3. This branch exits from the sartorius muscle at a point that varies slightly between individuals but remains consistent bilaterally in the same person 2.
Clinical Significance
Surgical Considerations
The infrapatellar branch is particularly vulnerable during medial knee procedures. In one study, 69% of patients experienced altered sensation after routine sectioning of the infrapatellar nerve during medial meniscectomy 2. When surgeons carefully protected this nerve branch during operation, no sensory alterations occurred 2.
Saphenous Neuritis
This nerve can be a source of medial knee pain through irritation or compression, a condition called saphenous neuritis 3. Key features include:
- Can mimic medial meniscal tears or osteoarthritis
- Characterized by allodynia (pain from normally non-painful stimuli) along the nerve course
- Diagnosis is confirmed by relief of symptoms after local anesthetic injection 3
- Palpation of the saphenous nerve should be part of every routine knee examination 3
Regional Anesthesia Applications
For procedures requiring motor-sparing anesthesia, a distal saphenous nerve block can be performed at a position distal and medial to the thigh, close to the femoral artery, and below the sartorius muscle 1. This approach avoids motor blockade of the quadriceps while providing sensory coverage of the medial leg.
Anatomical Landmarks
The saphenous nerve provides substantial innervation to:
- Medial knee capsule and retinaculum 4
- Periosteum of the medial malleolus 5
- Skin from the medial knee down to the base of the great toe 5
The infrapatellar branch has constant distal points of contact with the femur and tibia, making it accessible for therapeutic interventions when indicated 6.