so visceral and parietal pleura is just one continuous piece of membrane (actually 2 pieces since and left and right sides aren't connected. The reflection is the part where visceral (attached to the lungs) folds back and attaches to the inside of the thoracic cage and becomes the parietal pleura.
The significance of those ribs is so you know where to stick for a thoracentesis. You should aim for the part below where the visceral pleura ends but above where the parietal pleura ends that way you avoid poking the lungs and also avoid missing the pleural cavity altogether. Those levels also tell you what might be injured in a trauma, whether it's the lungs, the pleural cavity, or neither. It helps you figure out whether the person is at risk for a pneumothorax.
