The vastus medialis is one of the four muscles that make up the quadriceps, located in the front of the thigh. It plays a crucial role in extending the knee and stabilizing the patella, or kneecap, during movement. This muscle is particularly important for activities like walking, running, and jumping. Anatomically, the vastus medialis is situated on the inner side of the thigh and is often referred to as the "teardrop" muscle due to its shape. Strengthening the vastus medialis can help improve knee stability and prevent injuries, making it a focus in rehabilitation and fitness programs.