Deep tendon reflex：Physiology

First described in 1875 by Wilhelm Heinrich Erb and Carl Friedrich Otto Westphal, the deep tendon reflex (DTR) is essential in examining and diagnosing neurologic disease.[1] Deep tendon reflexes or, more accurately, the muscle stretch reflex can aid in evaluating neurologic disease affecting afferent nerves, spinal cord synaptic connections, motor nerves, and descending motor pathways. Proper technique and interpretation of results are crucial in achieving a proper distinction between upper and lower motor neuron pathologic processes such as multiple sclerosis (MS), amyotrophic lateral sclerosis (ALS), spinal cord injuries, and spinal muscular atrophies, with the presence of hyporeflexia or hyperreflexia considered a hard sign of neurologic dysfunction.

There are five primary deep tendon reflexes: biceps, brachioradialis, triceps, patellar, and ankle.

Biceps Reflex

Muscle involved: biceps brachii

Nerve supply: musculocutaneous

Segmental i...