In which position is the resident in a left side lying position with the lower arm behind the back?

The left side lying position with the lower arm behind the back is accurately described as the Sims position. This specific positioning is commonly used to facilitate certain medical examinations and procedures, particularly those involving the rectum or vagina. In Sims position, the person rests on their left side with the right leg bent at the knee and pulled up towards the abdomen, while the left arm is positioned behind the back. This setup provides better access and visibility while maintaining the patient's comfort.

In contrast, other positions like supine would have the person lying flat on their back without any lateral inclination, and prone would have them lying face down. Fowler's position involves sitting up at an angle and is typically used for patients who have difficulty breathing or for feeding. Therefore, the unique characteristics of the Sims position support the correct identification of this lateral positioning.