So once you've selected the linear probe and visualized the structure you want to access, it's important to understand how the ultrasound plane relates to both the structure you're visualizing and the needle. The terminology we prefer is in-plane versus out-of-plane. Sometimes you hear long axis, short access, but long axis really should be the relationship of the needle to the vessel - which in access procedures are always going to be long axis, whereas in-plane refers to the relationship of the needle to the plane of the ultrasound. So in this case we are seeing the needle enter the vessel and we can see the entire shaft and tip of the needle. This is in the plane of the ultrasound and the advantage is that when done correctly, you can see the entire needle including the tip. The disadvantage is that sometimes it can be tough to tell exactly where you are if you're not in line with the structure.