Which muscle is responsible for flexing the thigh and stabilizing the pelvis?

The sartorius muscle is the longest muscle in the human body and plays a crucial role in flexing the thigh at the hip joint. It also assists in flexing the knee and the external rotation of the thigh. This dual action is vital for stabilizing the pelvis during activities such as walking or running, as it helps maintain balance and proper alignment.

In contrast, while the rectus femoris is involved in thigh flexion, its primary function is to extend the knee, which differentiates its role compared to that of the sartorius. The adductor longus mainly functions to adduct the thigh, not primarily focusing on thigh flexion and pelvis stabilization. The tibialis anterior is responsible for dorsiflexing the foot and does not play a role in thigh movement or pelvis stabilization. Each of these muscles has specific functions, but the sartorius uniquely combines thigh flexion with pelvic stabilization, making it the correct answer.