3. Which muscle of the quadriceps group is located on the lateral surface of the lower extremity?
Answer: A
Vastus lateralis is located on the lateral surface of the lower extremity.
The vastus lateralis is one of the four muscles that make up the quadriceps group and is specifically found on the lateral aspect of the thigh.
A) Vastus lateralis
This option is correct because the vastus lateralis is indeed situated on the lateral surface of the lower extremity. It plays a crucial role in extending the knee and is the largest muscle in the quadriceps group, contributing significantly to leg strength.
B) Gastrocnemius
The gastrocnemius is incorrect as it is a calf muscle located at the back of the lower leg, not on the lateral surface. It primarily functions in plantar flexing the foot and bending the knee, and does not belong to the quadriceps group.
C) Anterior tibialis
The anterior tibialis is also incorrect. It is located on the anterior aspect of the lower leg and is responsible for dorsiflexion of the foot. This muscle does not belong to the quadriceps group and is not positioned laterally.
D) Rectus femoris
The rectus femoris is part of the quadriceps group but is located more centrally at the front of the thigh, rather than on the lateral surface. While it contributes to knee extension, it does not fulfill the requirement of being on the lateral aspect.
Conclusion
The vastus lateralis is definitively the correct answer as it is the only muscle in the options provided that is located on the lateral surface of the lower extremity. All other options either belong to different muscle groups or are situated in locations that do not meet the criteria specified in the question.