To be able to lift our arms overhead (lifting above 90 degrees) (as in Downdog, Hastasana or handstands), the whole shoulder girdle has to move together. As the arm lifts up, the scapula (shoulder blade) slides up the sides of the rib cage, and then the humerus (upper arm bone) rotates externally to make more room for the arm to lift over the shoulders. This is what we call scapulothoracic rhythm.
Two important things have to happen here:
First, your scapula has to rotate outwards and upwards along the side of your ribcage. Thatʼs what all the side bends and shoulder stretches are for. If the scapula doesnʼt rotate, and only the arm lifts up, the humerus pulls out of its socket, causing strain on the muscles and ligaments trying to keep it in. Thatʼs why you hear your teachers say:
- ” “draw your outer arms up and in”
- ” “wrap your triceps ”
- ” “hollow your armpits”
Second, external rotation of the arm is key to making sure you donʼt pinch at the top of the shoulder. How do you do that? Youʼve probably heard this before:
“roll your triceps forward/down” “spin your biceps towards your ears”
Without external rotation, the top of the arm bone pinches at space between the top of your shoulder and your arm where your muscles and nerves pass.
The combination of upward rotation of the scapula and external rotation of the humerus makes for a much better lift, and gives you much healthier shoulders. Now you know why your teachers sometimes say, “circle your arms overhead” when we start our sun salutations, and hopefully you can imagine it happening in your body too.
For more info, you may want to check out these links:
When she isn’t drawing body parts, you can find Tami Ledesma teaching Vinyasa, FNR, Gentle Flow, and Pre-Natal yoga at Urban Ashram, or pulsing among her students at Barre3. Follow her asana adventures on Instagram at @movewithtami.