What anatomical landmark is used as a guide for placing the upper extremity for the elbow?

The iliac crest is the correct anatomical landmark used as a guide for placing the upper extremity for the elbow. This is due to its location in the human body, where it provides a stable reference point that can help in proper alignment and positioning during various procedures or assessments involving the upper extremity, particularly the elbow.

The iliac crest is the curved superior border of the ilium, which is part of the pelvis. By using this landmark, practitioners can ensure that the upper limb is positioned correctly in relation to the body, allowing for more accurate anatomical assessments and interventions.

In contrast, the shoulders, cervical vertebrae, and scapula are not optimal landmarks for this specific purpose. The shoulders are more related to the connection between the upper limb and the torso but do not provide a direct guide to the elbow's positioning. Similarly, the cervical vertebrae are located in the neck and have no relevance to guiding the upper extremity, while the scapula, although related to the shoulder girdle and upper limb positioning, does not offer the same level of stability and reference as the iliac crest does for elbow placement.