What landmark is NOT associated with the respiratory system?

The femur is a bone located in the thigh, making it part of the skeletal system and not associated with the respiratory system. The respiratory system primarily involves structures such as the lungs, trachea, bronchi, and associated muscles that function in the process of breathing.

In contrast, the other landmarks referenced—the costal angle, clavicles, and xiphoid process—are all anatomically relevant to the thorax and respiration. The costal angle pertains to the angle formed by the costal margins at the junction where the ribs meet the sternum, and this is significant when assessing respiratory movements. The clavicles, or collarbones, are positioned at the top of the ribcage and play a role in the mechanics of respiration by providing support to the upper thorax. The xiphoid process, the small cartilaginous extension at the lower part of the sternum, is another landmark involved in evaluating the thoracic region, especially during respiration.

Recognizing these relationships helps in understanding the anatomy and function of the respiratory system and other interconnected structures within the thorax.