Tapping the triceps brachii muscle tendon will result in reflexive elbow extension. this is an example of a reflex.

This is an example of myotatic or stretch reflex. This is a muscle contraction that happens when there is stretching within a muscle. The myotatic reflex is a monosynaptic reflex, which provides automatic regulation of skeletal muscle length. A muscle spindle is stretched when a muscle lengthens. This increases nerve activity.