In instructing chaturanga, or four-limbed staff pose, one of the common cues you'll hear is to squeeze your upper arms to your ribs. I get it, it's a general guide and quick fix to prevent students from flaring the elbows outward (most common) and possibly pinching the shoulders and neck.
Here's my advice: don't squeeze, but keep upper arms close to the side body. If you squeeze, you'll likely collapse the front of the chest in the collarbone and throat area for a different kind of pinching. (Plus, this motion and shape doesn't support the chaturanga upper body you'll tap into for arm balances.)
But, I'd like to add this: exhale completely on the descent into chaturanga, and it might change your chaturanga practice forever.
Chaturanga is not just there to make your life hard or "make you sweat" in a "power" yoga class. It is one potential pose in Surya Namaskar, or sun salutations, a poetic combination of poses that allows you to physicalize reverence to Surya, the sun god or god of health, and to bow deeply into the cycle of the ebb and flow of each day.
Honestly, that's how I feel when I'm really feeling connected to my breath, so connect it to this pose and watch your chaturanga transform. The exhale will give you a physical lift in the sun-center of the manipura chakra (solar plexus chakra) and buoy your descent so you don't collapse belly-first or make some arm configuration in a desperate attempt to do this thing. If you can allow your breath to support you, you can gracefully lift your heart back up to greet the sun in upward dog.
Wow, I just had an a-ha moment: if you can allow your breath to support you, you can lift yourself up again and and again. If that isn't a perspective to take into your everyday life, what is?
Read the full chaturanga FAQ, including breakdown of the differences between chaturanga and a push-up (I interviewed a Barry's Bootcamp instructor for this) in Sonima: No, Chaturanga Is Not A Push Up.