Ultrasound pattern of the normal lung in B-mode with a linear transducer. The pleural line is depicted as the hyper echoic line limited between two sequential ribs. The backward and forward movement of pleural layers against each other occurs on the same level as the pleural results in lung sliding. The comet-tail artifact is a reverberation artifact arising from the pleural line and appears as a hyper echoic line parallel to the pleural line and at the depth of the parenchyma