If you feel self-conscious about having really skinny legs, you need to do some training to bulk them up. This infographic features 19 exercises you can do to take your legs up a few sizes. A Skinny Person's Guide to Gaining Weight
The triceps dumbbell kickback exercise focuses on the whole triceps, but in particular on the internal medial head of the triceps and furthermore on the external one. The exercise involves the lateral and rear deltoid as secondary muscles.