Which muscle is responsible for abducting and medially rotating the thigh?

The gluteus medius is primarily responsible for abducting and medially rotating the thigh. This muscle is located on the outer surface of the pelvis and plays a crucial role in stabilizing the hip during activities like walking or running. When the gluteus medius contracts, it pulls the thigh away from the midline of the body, leading to abduction. Additionally, when the thigh is flexed, the gluteus medius assists in medial rotation, helping maintain proper alignment and balance of the lower limb.

Other muscles, such as the gluteus maximus, primarily function in hip extension and lateral rotation rather than abduction and medial rotation. The piriformis also assists in lateral rotation but is not primarily involved in abduction. The rectus femoris, a muscle of the quadriceps group, is more focused on knee extension and hip flexion and does not play a significant role in the abduction or medial rotation of the thigh. Thus, the gluteus medius is the most relevant muscle for the actions specified in the question.