It is important to locate the probe on top of the first rib
With in-plane needle approach the needle tip will impinge on the rib instead of producing a pneumothorax, if the needle is inserted too deep
The movie shows the typical sonographic image when the probe is placed on top of the first rib P = pleura, c1 = first rib, SA = subclavian artery, asterixs = nerve divisions of the brachial plexus. Post = posterior, ant = anterior