The pes tendons are the attached tendon of the sartorius, gracilis and semitendinosus muscles, which insert together on the upper tibia on the medial side of the knee.

Harvesting tendons for cruciate ligament reconstruction
In the procedure of hamstrings harvest, the surgeon strips the tendons of semitendinosus (which is one of the hamstrings) and gracilis (which is actually not a hamstring) and combines them to make a quadrupled graft the reconstruct a torn cruciate ligament.
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CLINICAL PUBLICATIONS
Pes anserinus and anserine bursa: anatomical study. Lee J-H, Kim K-J, Jeong Y-G, Lee NS, Han SY, Lee CG, Kim K-Y and Han S-H. Anat Cell Biol. 2014 Jun; 47(2): 127–131.