Morphological variations of the human vastus lateralis muscle.

Variations in the gross morphology of quadriceps femoris were assessed in 40 cadavers. An additional (fifth) head was present in about one third of the limbs. Distally, fusion between vastus lateralis and vastus intermedius varied from almost complete fusion to less than one third of the interface between the muscles. Discrete tendinous laminae arising from vastus lateralis were present in 29% of the limbs. In half the cadavers there were differences in quadriceps topography on right and left sides but there were no significant differences between muscles from male and female subjects. These findings may have important implications in clinical and microscopic studies of the quadriceps muscle.