For the posterior oblique position (Grashey method) of the shoulder, which structure of the affected side should be parallel to the IR?

• A. Clavicle
• B. Scapula
• C. Humerus
• D. Coracoid process

Answer: (B)

In the posterior oblique position, commonly known as the Grashey method, the primary goal is to obtain an unobstructed view of the glenohumeral joint, which is the joint between the scapula and humerus. To achieve this, the scapula of the affected side must be positioned parallel to the image receptor (IR).

Positioning the scapula parallel to the IR ensures that the joint space is visualized without superimposition from other structures, allowing for proper assessment of the joint and surrounding anatomy. This technique also helps in evaluating conditions such as joint dislocations or degenerative diseases more effectively.

While structures like the clavicle and humerus are important for overall shoulder imaging, they do not need to be positioned parallel to the IR for this specific projection. The coracoid process, which is part of the scapula, is also not the primary focus of alignment in this position, as it is the overall orientation of the scapula that is critical for optimal imaging of the joint.