RESUMO
INTRODUCTION: The quadriceps femoris muscle is present in the anterior region of the thigh and is classically described as a muscle with four heads: rectus femoris, vastus lateralis, vastus medialis, and vastus intermedius. A few years ago, a "fifth head" was described and named the tensor of the vastus intermedius (TVI). The TVI belly is in line with the belly of the vastus lateralis, and its aponeurosis imposes considerable tension on the vastus intermedius, medializing its action, to play a significant role in knee extension. OBJECTIVE: To perform a study of the TVI incidence in a Brazilian population and describe its variations. MATERIAL AND METHODS: We dissected lower limbs from cadavers previously fixed in 10% formaldehyde, belonging to the Laboratory of Anatomy of the Department of Morphology of the Biosciences Center of the Federal University of Rio Grande do Norte. RESULTS: Eighty-one lower limbs were analyzed with only 33 (40.74%) of them presenting TVI. All four types of TVI described by the literature were present in our sample with the following distribution: type 1 with 15.15%; type 2 with 9.1%; type 3 with 33.33%; type 4 with 42.42%. DISCUSSION: Although the literature points to the TVI as a normal belly of the quadriceps, making it a "quinticeps", our analysis points to the TVI as a variation and probably a matter of regionality. However, the presence of TVI is not a rare case and cannot be disregarded, which makes this study important for anatomists, physiotherapists, physicians, and surgeons.