In McMurray test the knee is flexed while the leg is externally rotated, palpating the joint line with a finger. Then, the knee is slowly extended. The test for lateral meniscus is carried out by internally rotating the leg. Pain or a crackling sound is felt when the condyle engages in the meniscal lesion. (Rossi R, Bruzzone M, Dettoni F, Margheritini F: Clinical examination of the knee: know your tools for diagnosis of knee injuries).
Source: Rossi et al. Sports Medicine, Arthroscopy, Rehabilitation, Therapy & Technology 2011 3:25 doi:10.1186/1758-2555-3-25