Lateral patellar retinaculum
Muscles · Latin: Retinaculum laterale patellae
The lateral retinaculum is the fibrous tissue on the lateral (outer) side of the kneecap (patella).
The kneecap has both a medial (on the inner aspect) and a lateral (on the outer side) retinaculum, and these help to support the kneecap in its position in relation to the femur bone underneath it.
Definition from Wikipedia, CC BY-SA 4.0.