Abbreviations: SAG: Sagittal; POST: Posterior; LAT: Lateral; CEN: Central; MED: Medial The transducer positions used for sagittal imaging acquisition of the posterior aspect of the elbow joint at the level L1 are shown. The positions of the transducer placed laterally (B), centrally (C) and medially (D) in relation to the central position of the joint are illustrated with accompanying sonographic images in a healthy volunteer. The distal humerus (*) and ulnar olecranon (**) have been marked. The transducer positions used for sagittal imaging acquisition of the posterior aspect of the elbow joint at the level L2 are shown. The positions of the transducer placed laterally (E), and medially (F) in relation to the central position of the joint are illustrated with accompanying sonographic images in a healthy volunteer. The humeral lateral (*) and medial (**) epicondyles as well as radial head (***) and proximal ulna (****) have been marked. The transducer position used for sagittal imaging acquisition of the posterior aspect of the elbow joint at the level L3 is shown. The position of the transducer placed laterally (G) in relation to the central position of the joint is illustrated with accompanying sonographic images in a healthy volunteer. The radial head (***) has been marked.

Figure 4: The locations delineated with gel in prone position represent the positions of the transducer for acquisition of sagittal posterior images. The levels shown are L1. SAG, POS, LAT; L1. SAG, POST, CEN; L1 SAG, POST, MED; L2 SAG, POST, LAT; and L3 SAG, POST, LAT.