alar fold, 1. a fringed margin on either side of an infrapatellar fat pad in the knee joint formed by the synovial membrane. The synovial membrane covering the lower part of the infrapatellar fat pad is raised into a sharp midline fold directed posteriorly, the infrapateller synovial fold, which attaches to the margin of the intercondylar fossa of the femur. 2. a fold extending from the nostril to the ventral nasal concha.
