The Y-view is taken by aligning the plane of the scapula parallel with the x-ray beams so that it can be seen "floating" over the thoracic rib cage. In a healthy patient, the humeral head should be in alignment with the glenoid fossa of the scapula. If the glenoid fossa is not visualized directly, its position may be inferred from the spine of the scapula, the coracoid and the scapular body, which intersect at the glenoid fossa (they make a "Y"). However, following a traumatic dislocation, the humeral head will not be resting in the glenoid fossa.

You should be able to identify the spine of the scapula, body of scapula, coracoid, humeral head as it overlies the glenoid fossa, the humeral shaft and the clavicle.