The adductor longus is not considered a hip abductor because its primary function is to adduct the thigh, meaning it pulls the leg towards the midline of the body. While it is located in the inner thigh and contributes to stabilization of the hip joint, its role is distinct from the hip abductors, which are responsible for moving the thigh away from the body.
In contrast, the gluteus medius, tensor fasciae latae, and gluteus minimus all play key roles in hip abduction. The gluteus medius primarily helps in stabilizing the pelvis during activities such as walking and running, while the tensor fasciae latae assists in flexing and abducting the hip. The gluteus minimus, while smaller, also contributes to hip abduction and internal rotation. This clear distinction between adduction and abduction is why the adductor longus is categorized differently from the other muscles listed.