Accounting for variability in human morphology reduces iatrogenic injury and leads to positive clinical outcomes. Variations in the quadriceps femoris muscle group, including accessory muscular components, fascicular orientation, and relationships to the patellar tendon have been the focus of many research studies. Most reports describing variability associated with the rectus femoris muscle have closely examined common but underappreciated accessory muscular slips closer to the hip joint. Here we describe a significant accessory rectus femoris muscle belly in a 103-year-old white male donor discovered during anatomical dissection. The supernumerary muscle belly shared an origin from the ilium with the rest of the rectus femoris muscle and coursed through most of the thigh before blending with the distal vastus lateralis muscle. This finding prompted further investigation and a review of the literature.
