The Y view anatomy: The Y view is shot in an angle that separates the scapula and humerus from the ribs. It’s essentially a true lateral of the scapula. The scapula looks like a Y when viewed laterally. Laterally, the body of the scapula, acromion, and coracoid process all converge at the glenoid. If you connect straight lines through the axis of these structures, they will form a Y. If the humeral head falls in the middle of this convergence, then it is seated in the glenoid and there is no dislocation. If it is anterior to this convergence (or Y) then there is anterior dislocation. If it is posterior to this convergence there is posterior dislocation. Anterior dislocations are usually readily apparent with this view. Posterior dislocations can be more subtle and may require an axillary view if the Y view is not definitive.
Y View Anatomy