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

Femur

The femur , or thigh bone, is the most proximal bone of the leg in tetrapod vertebrates capable of walking or jumping, such as most land mammals, birds, many reptiles such as lizards, and amphibians such as frogs. In vertebrates with four legs such as dogs and horses, the femur is found only in...

 bone below it.

The lateral retinaculum is an extension of the fibrous 'aponeurosis' of the vastus lateralis muscle

Vastus lateralis muscle

The Vastus lateralis is the largest part of the Quadriceps femoris. It arises by a broad aponeurosis, which is attached to the upper part of the intertrochanteric line, to the anterior and inferior borders of the greater trochanter, to the lateral lip of the gluteal tuberosity, and to the upper...

 (itself a part of the quadriceps muscle

Quadriceps muscle

The quadriceps femoris , also called simply the quadriceps, quadriceps extensor, quads, is a large muscle group that includes the four prevailing muscles on the front of the thigh...

s making up the 'lap').

External links

• Patello-femoral Pain Syndrome {This article has a good image}
• The KNEEguru - educational site packed with knee content with sections on the lateral retinaculum