Deep tendon reflexes and their grading !

Exam technique

A tap of the hammer on a tendon that triggers an automatic contraction; it checks nerves, roots and spinal cord.

Updated 2026-11-01

See it in 3D: Patellar tendon · Achilles tendon · Distal biceps tendon · Triceps tendon · Brachioradialis tendon · C5 nerve root · C6 nerve root · C7 nerve root · L4 nerve root · S1 nerve root

What it is

The deep tendon (stretch) reflex is a single-synapse arc: the tap stretches the muscle, the muscle spindle sends a signal through the dorsal root and the anterior horn motor neuron answers with a contraction. Each reflex tests one spinal level, and its strength shows whether a lesion is in the lower motor neuron (reduced reflex) or the upper motor neuron (brisk reflex).

Key facts

0: no response, even with reinforcement.
1+: weak response, or one that appears only with reinforcement.
2+: normal response.
3+: brisker than normal, without clonus; may be normal if symmetric.
4+: very brisk response with clonus.
What matters most is asymmetry between the two sides.

Landmark anatomy

Biceps: musculocutaneous nerve; brachioradialis and triceps: radial nerve.
Patellar: femoral nerve and quadriceps; Achilles: tibial nerve and triceps surae.
The corticospinal tract normally damps the reflex arc; when it is damaged, the reflex becomes brisk.

Technique, step by step

Ask the patient to relax and place both limbs in the same position, with the muscle slightly stretched.
Hold the hammer loosely at its end and let it fall with a quick flick of the wrist.
Strike the tendon (or the examiner's finger placed on it) and watch and feel the contraction.
Test the same reflex on the other side at once to compare.
If there is no response, use Jendrassik reinforcement: interlock the fingers and pull hard (for the legs) or clench the teeth (for the arms).
Grade each reflex from 0 to 4+ and record it on a stick-figure diagram.
If a reflex is very brisk, look for ankle clonus, a Hoffmann sign and the plantar response.

Deep tendon reflexes: root and technique

Reflex	Root	How to elicit it
Biceps	C5–C6	Elbow half-flexed; the examiner's thumb on the biceps tendon, strike the thumb
Brachioradialis (supinator)	C6	Forearm resting, half-pronated; strike the radius a few centimetres above the wrist
Triceps	C7	Arm supported with the elbow at 90°; strike the triceps tendon above the olecranon
Finger flexor	C8	Fingers loosely flexed over the examiner's fingers; strike the examiner's fingers
Patellar (knee jerk)	L3–L4	Seated with the legs hanging; strike the patellar tendon below the kneecap
Achilles (ankle jerk)	S1	Dorsiflex the foot slightly and strike the Achilles tendon

Abnormal findings

Generalised hyporeflexia: polyneuropathy, Guillain–Barré syndrome, hypothyroidism.
A single reduced reflex: radiculopathy (biceps C5–C6, triceps C7, patellar L4, Achilles S1).
Hyperreflexia below a level with normal reflexes above it: a spinal cord lesion at that level.
Hyperreflexia on one side of the body: a lesion of the opposite hemisphere or brainstem.

Common errors

Tapping while the patient is tense or watching the hammer; distraction with Jendrassik improves the response.
Calling a symmetric 3+ reflex abnormal with no other signs: many anxious young people have one.
Ankle jerks fade in old age.

Test yourself

Think of the answer, then tap the question to see it.

Which root does the Achilles reflex test?

The S1 root, through the tibial nerve; its loss with sciatica suggests an L5–S1 disc herniation.

What does a reflex graded 4+ mean?

A very brisk reflex with clonus, a sign of an upper motor neuron lesion.

What is the Jendrassik manoeuvre for?

To reinforce a weak reflex: the patient interlocks the fingers and pulls hard while a leg tendon is struck, so a reflex that was only inhibited is not called absent.

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See it in 3D

The structures of Durgical's 3D anatomy where it is found.

← All of the clinical exam

Educational content on the clinical exam; it is learned and practised under supervision. It does not replace assessment by a health professional and is not for self-diagnosis.

Sources: How To Assess Reflexes (MSD Manual Professional Edition, 2024); 26.2 Physical Assessment - Clinical Nursing Skills (OpenStax, 2024); 16.4 The Sensory and Motor Exams (OpenStax, Anatomy and Physiology 2e, 2022).

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Representative model, for educational purposes only.