Lateral retinaculum is an aponeurosis
The lateral retinaculum around the patella is an extension of the fibrous 'aponeurosis' of the quadriceps muscles.
An aponeurosis is a fibrous sheet-like expansion of a tendon, for example of the biceps femoris or quadriceps muscles.
The lateral retinaculum around the patella is an extension of the fibrous 'aponeurosis' of the quadriceps muscles.