Underside of the first rib
 

Are there muscles that attach to the underside of the first rib?

It's easy to see at the following web page that the muscles that attach to the top are the scalenus medius and scalenus anterior, which combined with the first rib form the "axis of evil"--at least from a TOS sufferers perspective. :)

http://en.wikipedia.org/wiki/First_rib

What exactly is on the underside? Any good pics, diagrams or sources for that?

The intercostal muscles
http://en.wikipedia.org/wiki/Muscles...costal_muscles

"Both the external intercostal muscles and the intercondral elevate the ribs, thus increasing the width of the thoracic cavity..."

Which to me implies that they wouldn't aid with pulling the rib down. But then later it says "The abdominal muscles and the internal and innermost intercostal muscles help expel air."

I guess I was wondering what muscles could pull the first rib down and how?

What seems to be widely misunderstood/assumed here is that everyone's structure, scar tissue, abnormalities, etc. are the same. Dr. Donahue said he would not know exactly what to expect until he got into the shoulder. There are so many variables you can't predict what the outcome will be.

There's no misunderstanding here at all. I'm aware of the variance, but that doesn't apply to my question. Consider that questions such as "What can cause the first rib to elevate?" are made with the implication "in typical anatomy" and are still of interest as we research TOS. For that question, the correct answer is "The two scalene muscles that attach to the topside of it."

Likewise there may be a correct answer for "What muscle action can cause the first rib to come down?".

Also, even for things that vary immensely such as "What gives you symptom relief?" we see an uneven distribution in the answers that come back. For example, popular answers include ice packs, heating pads, supporting the arm and corpse pose, while we don't typically see qigong, contact sports or pushups as a reply. So even the "soft" questions are interesting to get answers to.

Anyway, I'm curious if a forced exhalation causes the inner intercostals to contract and provide a downward pulling force on the first rib. If that were the case, then forced exhalations could be part of a conservative care approach to TOS.

Chroma, this was the question you asked. I simply pointed out that there are lots of anatomical variants, so maybe there should be muscles underneath the rib, but maybe you don't have them.

It seems that some things vary and others do not. For example, has a surgeon ever opened someone up and found that they had no ASM? I've never heard of that.

The top side of the rib gets a lot of attention on these forums and at any TOS page. I never hear anything about the underside. I don't even know for certain that the first and 2nd rib are connected by intercostals. Are they?

My lay opinion -

The first and second rib are connected by the intercostals.

Forced exhalation, in theory, should lower the first rib. A conservative maneuver to help this process would be to inhale diaphragmatically with a pelvic tilt upwards and then force exhalation as you press your lower back to the floor and move your diaphragm downwards.