The biceps muscle is in the front of your upper arm. It helps you bend your elbow and rotate your arm. It also helps keep your shoulder stable.
Tendons attach muscles to bones. Your biceps tendons attach the biceps muscle to bones in the shoulder and in the elbow. If you tear the biceps tendon at the shoulder, you may lose some strength in your arm and be unable to forcefully turn your arm from palm down to palm up.
Many people can still function with a biceps tendon tear, and only need simple treatments to relieve symptoms. Some people require surgery to repair the torn tendon.
http://orthoinfo.aaos.org/topic.cfm?topic=A00031