What happens if tendons are stretched?

A muscle or tendon will tear when injured, this is called a strain, or more commonly, a pulled muscle. A tendon can be just irritated, in this case it will become inflamed and called tendinitis. If there is a tendon sheath involved, it will be called tenosynovitis. In most cases, applying anything cold will help. If in doubt, or it continues more than a few days, it is best to see a doctor.