Arms

The arm’s curved shape comes from its major exterior muscles. These bulky muscles also give the arm its strength.

The muscles of the arm that can be seen easily on the surface include:

• Biceps: This large muscle of the upper arm is formally known as the biceps brachii muscle, and rests on top of the humerus bone. It rotates the forearm and also flexes the elbow.
• Triceps: This large muscle in the back of the upper arm helps straighten the arm. It is formally known as the triceps brachii muscle.