To obtain a posterior shoulder view: Have the patient sit up with the back of the bed down. Position the curvilinear probe in the posterior aspect of the shoulder with the probe parallel to the patient bed, at the level just below the scapular spine and the marker towards the patient's left. You can have the patient rotate their arm to help you visualize the movement of the humeral head.
In the normal anatomy, the humeral head should be at the level of the glenoid (this is a patient's left shoulder):
Locate the glenohumeral joint space. You can evaluate the GH joint for effusion, perform joint arthrocentesis/injection and look for signs of shoulder dislocation.
If you are evaluating for signs of a dislocation:
Posterior dislocation: the humeral head will be more SUPERFICIAL in the image than the scapular spine
Anterior dislocation: the humeral head will be DEEPER in the image than the scapular spine.
