Anatomy Snack- the Phrenic Nerve

If you're a person who enjoys breathing, you should know about the phrenic nerve.

Chances are high that at some point over the last couple years you've heard about the vagus nerve. Maybe from a social media post, maybe in relation to nervous system regulation (so hot right now) or improving your sleep and digestion. I get it. The vagus nerve is cool. But there's another nerve right next door that you use around 20,000 times a day without even thinking, and if this nerve ceased to function, so would you.

Obviously I'm talking about the phrenic nerve, which technically speaking is a pair of nerves. They run from your neck (from c3, 4, and 5 if we're being specific) down the sides of your neck, through the middle mediastinum, around your heart, and end at your diaphragm. This essentially makes its a communication expressway between your brain and diaphragm, enabling your diaphragm to move so you can breathe.

Besides the obvious appeal of keeping you alive, there are a couple other interesting things about the phrenic nerve. When it gets irritated it can cause the diaphragm to spasm, creating persistent hiccups. Even more odd, when this nerve is grumpy it can cause shoulder pain, a result of the nervous system essentially getting its wires crossed. The phrenic nerve and the supraclavicular nerves both come from C3 and 4. Sometimes the body can misread a signal from the phrenic nerve as a message from the supraclavicular nerve, which supplies sensation to the skin of the shoulder. This can lead to our old friend- referred pain. This is a situation where visceral manipulation can be a super effective tool by helping to reset the tension and position of the phrenic nerve and calm the irritation. If you've been coming to see me for persistent shoulder pain, there is a 10/10 chance I've had a chat with your phrenic nerve to rule it out as a cause.

So at this point you're undoubtedly wondering how you can support the health and function of this crucial structure, and I'm so glad you asked. The most basic answer- you breathe and you move! While it's a bit of a myth that you can "strengthen" nerves, you can make it easier for them to do their job. Nerves do not like to be stretched or pinched or compressed. They like to be able to glide freely along their track and feel safe and secure.

Unfortunately, because of the phrenic nerve's path along the neck and through the mediastinum, opportunities for compression are all too common. Also, thanks to stress and our increasingly sedentary lives, shallow and dysfunctional breathing patterns can easily take hold and become our primary habits. While there are endless videos about "diaphragmatic" breathing on YouTube (uh, all breathing is diaphragmatic), the topic is way too nuanced for me to suggest a generic exercise and send you on your way. If you have questions or concerns about your breathing mechanics, it's always best to be assessed by a professional who can give you appropriate guidance so you don't at best waste your time or at worst exacerbate the problem. I am always more than happy to talk breathing during a session!

Happy breathing!