Final answer:
The Quadriceps femoris group, which consists of four muscles, is located on the anterior part of the thigh and is responsible for extending the knee. The gastrocnemius is the largest muscle in the lower leg, part of the posterior compartment, principally involved in plantar flexion.
Step-by-step explanation:
The muscle group located on the anterior part of the thigh is the Quadriceps femoris group. This group consists of four muscles: the rectus femoris, the vastus lateralis, the vastus medialis, and the vastus intermedius. These muscles are responsible for extending the knee and playing a significant role in movements such as kicking and raising the knee. On the other hand, the posterior compartment of the thigh houses the hamstrings, which are responsible for flexing the knee.
The largest muscle in the lower leg, relevant to another question, is the gastrocnemius. This two-headed muscle forms the bulk of the calf and functions in plantar flexing the foot at the ankle joint and flexing the leg at the knee joint. Meanwhile, the soleus is a smaller muscle located deep to the gastrocnemius and also contributes to plantar flexion.
In summary, for the student's question, the final answer in a two-line explanation: The quadriceps group is located on the anterior part of the thigh and is mainly concerned with knee extension. The hamstrings, located in the posterior compartment of the thigh, act as antagonists and handle knee flexion.