Final answer:
The elbow should be perpendicular to the CR when imaging the intercondylar fossa, not the hand or foot. Additionally, the origin of the wrist flexors is the medial epicondyle of the humerus.
Step-by-step explanation:
The body part that should be perpendicular to the central ray (CR) when imaging the intercondylar fossa is the elbow. This is typically part of an orthopedic imaging procedure to visualize the intercondylar fossa of the femur, but the elbow itself has structures such as the olecranon fossa which could also be examined if the question pertains to the elbow joint. In either case, proper alignment is crucial to obtain accurate diagnostic images. The elbow should be positioned in such a way that the central ray can pass through the intercondylar fossa to capture the appropriate details of the joint space.