Keywords:
Tissue characterisation, Education and training, Localisation, Diagnostic procedure, Ultrasound-Colour Doppler, Ultrasound, Neuroradiology peripheral nerve, Musculoskeletal system, Anatomy
Authors:
M. De Cesari1, E. Massone1, G. Rebella1, S. Perugin Bernardi2, G. Buonomenna1, V. Picasso2, A. Muda2, D. Orlandi2, E. Silvestri1; 1Genoa/IT, 2Genova/IT
DOI:
10.26044/essr2019/P-0056
Background
The saphenous nerve is the longest terminal branch of the posterior division of the femoral nerve and the only one below the knee that is not derived from the sciatic nerve.
After its origin in the femoural triangle,
it descends laterally to the femoral vessels and deep to the sartorius muscle to enter in the adductor or Hunter’s canal.
In the distal third of the adductor magnus muscle,
the saphenous nerve crosses over the femoral vessels to lie on their medial side and,
just above the medial aspect of the knee,
the nerve pierces the roof of the subsartorial canal.
The saphenous nerve continues distally dividing into two terminal branches: infrapatellar and descending (Fig.1).
Infrapatellar branch reaches the subcutaneous to innervate the infrapatellar fat pad and the anteromedial part of the knee.
Descending branch has a subcutaneous course in the medial side after crossing the sartorial muscle or the superficial fascia between the gracilis and sartorius muscle and follows the course of the great saphenous vein.
At the level of the ankle,
this branch occurs between the medial malleolus and the anterior tibial tendon and approximately 3 cm proximally to the tip of the medial malleolus,
it splits into anterior and posterior branches.
Along its course the descending branch of the saphenous nerve provides articular branches to the knee and ankle and sensory innervations to the skin and fascia on the anteromedial aspect of the leg and foot to the first metatarsal.
Ultrasonography is commonly used to assess the peripheral nerves that present a characteristic "honeycomb" appearance in short axis and “electric cable” appearance in long axis.
We will provide a dedicated US saphenous nerve image compared with a detailed anatomic scheme,
and a practical guide on “how we do” a US scan.