“My Arm Goes Numb” – Is it Thoracic Outlet Syndrome?
October 10th, 2009
I attended massage school at the Downeast School of Massage in Waldoboro, Maine. This meant an hour and a half commute each way, 3-6 days per week, for close to a year.
The commute goes up Route 1, with lots of speed changes and traffic lights. My car is a stickshift, so most of the commute I held my left arm out in front, with my hand on the wheel, while my right arm worked the gearshift. Posture is a type of repetitive action just like any other, and the muscles on the front left side grew tight and overused.
Eventually, my left arm would go numb at night if I lay on my side, and I lost grip strength in my left hand. This is not good for a budding massage therapist!
Coincidentally (or perhaps not so coincidentally), about the time this started to bother me, we discussed a condition in Pathology class called thoracic outlet syndrome. Immediately, I knew this was my issue. I treated myself with some focused stretching & self-massage, and quickly regained function.
Thoracic outlet syndrome is named for the thoracic outlet, which is the space between your collarbone and your first rib. This is a narrow passageway, but it is crowded with blood vessels, nerves, and muscles. If muscles in this area are tight, they can make the thoracic outlet even smaller, constricting nerves or blood vessels.
The primary muscles involved in this condition are anterior deltoid, subclavius, and (most especially) pectoralis minor.
Pectoralis minor is a deep muscle that runs diagonally across your chest from your shoulder to the middle of your ribcage. It’s the red structure with three main “branches” in this image:
As you can see, pec minor directly covers the thoracic outlet, and when it is tight, can draw the shoulder down, compressing nerves (in yellow) and arteries and veins (red & blue).
There are many ways to treat this condition, including surgery. However, massage therapy and stretching are gentle, non-invasive way to start treating this issue before it gets any worse.
Next time you see me, ask for tips on stretching and self-massage for this area. In the meantime, check out this video of a guy performing a very simple stretch for pec minor:
http://www.youtube.com/watch?v=aEtuF9m_xOY
This bodybuilder doesn’t have the best form in the world, but at least he’s stretching! And something about the video just cracks me up. There are better stretches available – ask me about the “active assisted doorway stretch” next time you come in for your appointment.