Work that peak, bro.
I COMMAND YOU TO GROW - yelling this while deadlifting might make them get bigger.
Side note -
My arms definitely got bigger by simply doing the lifts, putting 200lbs on my deadlift, 100lbs on my bench, 100lbs on my press, and gaining 70lbs of bodyweight.
I have noticed that after a while, my arms stopped getting bigger while my shoulders/back/chest/legs continued to get bigger. I'm still skinny as balls, but now with very broad shoulders.
Currently 6'4, 225 (I used to be concentration camp skinny) but I am starting to look odd with a big torso and spindly limbs.
My current approach is to just gain another 40lbs.
Work that peak, bro.
All kidding aside, I think there is a genetic component to some of this. Some people's arms get bigger through the barbell lifts coupled with chins and/or weighted chins. This is especially true in the novice phases where skinny peeps put on bodyweight. Some people's arms require curlz and other assistance lifts to grow. I would bet that barbell training + arm work aids with getting bigger arms more effectively than just doing arm work alone. My experiments with drinking Coke Zero to stimulate biceps hypertrophy have been unsuccessful so far. I will keep trying.
Coke Zero tastes like how cats smell
Curl after every work out, put the blood back where it belongs peasants.
Certainly the triceps even more, proportionally I'd say. But there is a noticeable difference in the biceps as well.
For clarification, my favorite exercises before having a program were row varieties and I'd curl some. Still did not experience the same biceps growth. So even though I still row, the biggest and starkest programming difference (of all of them) is squatting every day.