CAMRT Radiography Practice Exam

In a scapular Y view, how can you distinguish between an anterior and posterior dislocation?

1. By the position of the humeral head relative to the coracoid or acromion

2. By evaluating the scapular outline

3. By examining the position of the clavicle

4. By the angle of the arm in the projection

The correct answer is: By the position of the humeral head relative to the coracoid or acromion

In a scapular Y view, distinguishing between an anterior and posterior dislocation of the shoulder relies primarily on assessing the position of the humeral head in relation to the anatomical landmarks of the scapula, specifically the coracoid process and the acromion. In an anterior dislocation, the humeral head typically migrates forward and is positioned beneath the coracoid process, making it more prominent in that area. Conversely, in a posterior dislocation, the humeral head shifts backward, often resulting in it being located behind the acromion. This clear positional relationship allows for a straightforward assessment of the type of dislocation based on where the humeral head is situated relative to these notable structures. Other factors like evaluating the scapular outline, examining the position of the clavicle, or the arm's angle in the projection may provide additional supportive information, but they are not definitive indicators for distinguishing between anterior and posterior dislocations in the context of the scapular Y view. The critical aspect of identifying the type of dislocation hinges on the specific relationship of the humeral head to the coracoid and acromion.