It's my secret X-men ability.

May 29, 2007 9:44 AM

MutantFilter: For as long as I can remember, I've had what I thought was a muscle missing in my upper right arm. I've never seen anyone else with this, nor have I been able to figure out if that's it for sure. Anyone who knows something about anatomy want to take a look at this? (Pictures included.)

I've always had this "line" or indentation running across part of my upper arm where it looks like a muscle should be, but isn't. Until now, I've figured some muscle must be missing because I can poke that part of my arm and feel the bone in there, but looking at muscle diagrams and stuff hasn't helped to figure out which one(s) are missing, exactly.

Other people have suggested that it's not a muscle missing after all, mainly because I would have a limited range of motion in my arm or other movability issues with it if it were.

Pictures here, here, and here.

Any ideas as to what this is?

posted by flod logic to health (20 comments total)

It just looks like a normal muscle striation to me.
posted by Loto at 10:01 AM on May 29, 2007

I'm failing to see whats supposed to be missing
posted by bitdamaged at 10:02 AM on May 29, 2007

Here's a picture of what's going on. It looks fine to me, a random guy on the internet.
posted by Floydd at 10:02 AM on May 29, 2007

Unless there is something not captured by these pics, that is normal muscle tone.
posted by spicynuts at 10:06 AM on May 29, 2007

You've been blessed with muscle definition. I'm not an expert at muscle groups myself, but I'd guess that's the definition between the deltoids and the triceps.

If you want more evidence, just google various combinations of muscle, definition, deltoids, etc. "Other people" are correct; if you were missing a muscle, you quite literally would be unable to move in a certain direction.
posted by artifarce at 10:06 AM on May 29, 2007

I don't think it's muscle definition because the other arm doesn't look like that at all.
posted by flod logic at 10:17 AM on May 29, 2007

I don't know what is going on exactly, but I have a similar "hole" in my calf muscle, so you are not alone.
posted by stormygrey at 10:22 AM on May 29, 2007

You're not a tennis player by any chance are you?

Are you rotating your arm (thumb down) in these pics? Sometimes peoples triceps develop a bit more rotated around the arm then others, in fact mine both do, and seem to look like yours.

I assume for me its from being a competitive swimmer 365 days a year from when I was 8 until I was in my 20s but I think I've seen similar on tennis players.
posted by bitdamaged at 10:26 AM on May 29, 2007

Looks totally normal.
posted by dead_ at 10:28 AM on May 29, 2007

I can touch my humerus between the muscles there too fwiw, given appropriate rotation of the shoulder joint.

Side note: about 16% of the Caucasian population is in fact missing a muscle in their forearms, the palmaris longus.
posted by pharm at 10:36 AM on May 29, 2007

Bodies aren't perfectly symmetrical. My arms look different simply because I use one more.
posted by DieHipsterDie at 10:38 AM on May 29, 2007

I think we are crushing flod logic's hopes to become a mutant. So here's my take: totally mutant arm, esp if it does not look like the other one (or two) that you also have :)

all in good jest - seriously, I don't see anything wrong either.
posted by seawallrunner at 10:45 AM on May 29, 2007

Bitdamaged: No, I'm not a tennis player, nor do I work out or exercise at all. My arm is rotated downwards, but that's only to show it a little better.

Maybe I should've compared them from the beginning, but here is the left and right arm.
posted by flod logic at 10:57 AM on May 29, 2007

Are you right handed? Could be that your right arm is just more muscular/developed than the left. This was definitely the case for me, before I took steps to "even them out". Your right arm looks pretty much like both of my arms.
posted by backwards guitar at 11:01 AM on May 29, 2007

I am right-handed and I think my right arm is slightly more muscular than the left, but it doesn't account for the fact that the indentation/hole has been there since I was a baby.
posted by flod logic at 11:15 AM on May 29, 2007

I have something similar in my left quadricep. I could by no means be described as muscular, so it's not muscle tone. I've never gotten it checked out, so I can't tell you what it is - I just wanted to tell you you're not alone (and to ask when should we plan our super secret mutant meetings?)
posted by twoporedomain at 11:25 AM on May 29, 2007

I don't think it looks like standard muscle definition, especially when judged side-by-side with the other arm. To me it looks like maybe the lateral deltoid is missing or atrophied and the anterior deltoid has compensated for it. Take a lot at this , particularly the abduction link. Do the movements shown while trying to feel the muscle flex with the opposite hand. Compare to the other arm of course. Also try movements for the anterior deltoid to see if you can isolate which muscles are which.
posted by Durin's Bane at 11:34 AM on May 29, 2007 [1 favorite]

You could try to figure out the muscle missing through a functional test. This link contains videos of several movements and describes the muscles responsible. Try having someone hold your arms down while you abduct, adduct, extend, flex, etc and see if you sense any differences in strength between the right and left side. Knowing the motions that are loss or intact, you can figure out the muscle responsible with the website above.
posted by alex3005 at 1:44 PM on May 29, 2007

I think Durin's Bane is exactly right (and has linked an excellent site).
posted by jamjam at 4:26 PM on May 29, 2007

I wish I had muscle tone like that. Thank your lucky genes for those guns!
posted by HotPatatta at 12:38 AM on May 30, 2007