How do I increase the length of my bicep muscles?

I do preacher curls more than anything else, and my bicep muscle is still only 1/3rd of my arm from shoulder to elbow. I repeat, my bicep is still just 1/3rd of my arm. My arms look absolutely ridiculous.
I am desperately looking for any direction.

Answers:

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Seems approaching you need some up to date exercises.Try this get an incline bench,incline it to a 15 point angle lay back and next to 2 dumbells do a set of curls.This should burn your bicep muscle.

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Increase the weight by 5 pounds, do 5-8 reps beside 5 sets. Eat more, get 8 hours of sleep and afterwards you'll grow. Increase the weight by 5 pounds every 1-2 weeks.

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dude stop the preacher curls...immediatly...use a standing position next to a straight bar...relatively wide-ranging grip...al the way up and adjectives the way down...

also do some dumbells close to that, or seated one arm at a time...with your elbow on your knees...all the passageway up and down...you just get lazy on the full motion...do the full moion and the muscle should steep in summarily...

certain vitamins?

you can't increase the length its genetics