The biceps brachii muscle, located on the anterior side of the upper arm, is a pike-shaped muscle that flexes the forearm when contracted. The biceps reflex can be examined by seating the patient in a chair, with the doctor’s left hand supporting the patient’s elbow, the left forearm supporting the patient’s forearm, and the thumb of the left hand pressing on the patient’s biceps tendon, and using a percussion hammer to tap the thumb pressing on the tendon. With a normal response, that forearm will flex. However, if the response is hyperactive, decreased, or absent, this indicates an abnormal biceps reflex. Biceps reflexes can be abnormal when the arm is functionally atrophied, when the muscle is strained, or when the tendon is injured. However, a biceps reflex that is not increased or decreased on examination is normal and not cause for concern.