A plexus is a network of nerves or blood vessels that branch out and weave together like a tangle of cords behind a computer.

Your body contains several important plexuses. The solar plexus, located in your abdomen, is a dense cluster of nerves that helps control your digestive system. When you get punched or hit hard in the stomach, that sharp, breathless feeling can come from impact to the solar plexus. The brachial plexus in your shoulder controls the nerves in your arms and hands. If you've ever slept on your arm wrong and woken up with it completely numb and tingly, that happened because you compressed part of your brachial plexus.

Scientists and doctors use the word plexus whenever they need to describe these biological networks where many pathways intersect and communicate. Think of a plexus like a major highway interchange where multiple roads meet and branch off in different directions, except instead of cars, your plexus carries nerve signals or blood throughout your body.