Final answer:
A deep tendon reflex, also known as a stretch reflex, is the automatic motor response assessed by striking a tendon, resulting in involuntary muscle contraction for stability and postural control.
Step-by-step explanation:
An assessment of an automatic motor response by striking a tendon is known as a deep tendon reflex or stretch reflex. This involves rapid, involuntary contraction of muscles after a tendon is tapped. Common reflexes tested during a neurological exam include the biceps, brachioradialis, and triceps for the arm and the knee and ankle reflexes for the leg. When assessing reflexes, the muscle's tendon is struck with a rubber mallet, triggering a reflex that involves activation of the muscle spindle, signal transmission through the spinal cord, and muscle contraction mediated by the motor neuron. Such reflexes serve an important role in maintaining stability as they help muscles quickly compensate for changes in length.