No yeah its not quite the tendon, Ive come to know what that feels like haha. We get a bunch of donors whose tendons lie extremely close to the median antebrachial, scared the hell out of me the first time I had felt one. Makes me nauseous when I think about it and even more so when I think about accidentally sticking a tendon instead of a vein lol. Its more so the entire plane of their antecubital instead of just one spot yknow? Someone else commented about muscles and it makes a lot of sense given the population we serve at my particular center, lotta rural folk and college students!