Your triceps muscle makes up close to 60 percent of your upper arm. So giving your triceps as much attention as your biceps will help you increase your arm size faster than focusing only on the muscles in front (biceps). Many guys unfairly focus on their biceps, thinking that the key to bigger arms lies in doing more curls.
There are four main categories of exercises for the triceps from which you can benefit: (1) Cable push-down, (2) Triceps extension, (3) Triceps kickback, and (4) Narrow grip press.
Each category has several versions, which guarantees a great variety of movements and allows you to choose the ones that best suit both your anatomy and your goals.
As the name implies, the triceps muscle has three heads, all similar in function. While there is evidence that each muscle head can be trained individually with specific exercises, most research indicates that genetics rather than training may be responsible for any differences. For beginners, focus on good execution of all extension exercises. A common goal is to make this muscle have a horseshoe-like appearance when it is contracted.
Bigger, stronger triceps also play a key role in bench pressing and assist on back exercises, so if you want to get your arm-training priorities straight, start with this category.