Posterior Shoulder Dislocation: Anteroposterior and Y Views

In the left image (anteroposterior view), the humeral head is internally rotated, resulting in the light bulb or ice cream cone sign (projections of the greater and lesser humeral tuberosities are not seen), which suggests a posterior dislocation. In the right image (Y view), the humeral head is posterior to the glenoid fossa, which demonstrates a posterior dislocation.