[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Clinical exam](https://durgical.com/en/clinical-exam/) › [Nervous system](https://durgical.com/en/clinical-exam/#a-neuro) › Deep tendon reflexes and their grading

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# 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](https://durgical.com/en/anatomy/patellar-ligament/) · [Achilles tendon](https://durgical.com/en/anatomy/calcaneal-tendon/) · [Distal biceps tendon](https://durgical.com/en/anatomy/distal-biceps-tendon/) · [Triceps tendon](https://durgical.com/en/anatomy/triceps-tendon/) · [Brachioradialis tendon](https://durgical.com/en/anatomy/brachioradialis-tendon/) · [C5 nerve root](https://durgical.com/en/anatomy/c5-spine-and-pelvis/) · [C6 nerve root](https://durgical.com/en/anatomy/c6-spine-and-pelvis/) · [C7 nerve root](https://durgical.com/en/anatomy/c7/) · [L4 nerve root](https://durgical.com/en/anatomy/l4/) · [S1 nerve root](https://durgical.com/en/anatomy/s1/)

## Key points

- Roots: biceps C5–C6, brachioradialis C6, triceps C7, patellar L3–L4, Achilles S1.
- Grading: 0 absent; 1+ reduced; 2+ normal; 3+ brisker than normal; 4+ very brisk with clonus.
- Reduced or absent reflex: lower motor neuron (root, nerve, polyneuropathy, Guillain–Barré); also in acute spinal shock.
- Brisk reflexes with clonus and a Babinski sign: upper motor neuron.
- Absent ankle jerk with sciatic pain: S1 radiculopathy (L5–S1 disc herniation).

## 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.

## Memory aid

Count from the bottom up: 'S1 at the ankle, L3–L4 at the knee, C5–C6 at the biceps, C7 at the triceps'.

## 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.

[Add to my cards (3)](https://durgical.app/estudiar/?add=/en/clinical-exam/deep-tendon-reflexes-and-their-grading/)

## See it in 3D

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

- [Patellar tendon](https://durgical.com/en/anatomy/patellar-ligament/)
- [Achilles tendon](https://durgical.com/en/anatomy/calcaneal-tendon/)
- [Distal biceps tendon](https://durgical.com/en/anatomy/distal-biceps-tendon/)
- [Triceps tendon](https://durgical.com/en/anatomy/triceps-tendon/)
- [Brachioradialis tendon](https://durgical.com/en/anatomy/brachioradialis-tendon/)
- [C5 nerve root](https://durgical.com/en/anatomy/c5-spine-and-pelvis/)
- [C6 nerve root](https://durgical.com/en/anatomy/c6-spine-and-pelvis/)
- [C7 nerve root](https://durgical.com/en/anatomy/c7/)
- [L4 nerve root](https://durgical.com/en/anatomy/l4/)
- [S1 nerve root](https://durgical.com/en/anatomy/s1/)

## Related

- [The neurological examination: order and screening exam](https://durgical.com/en/clinical-exam/the-neurological-examination-order-and-screening-exam/)
- [Babinski sign](https://durgical.com/en/clinical-exam/babinski-sign/)
- [Hoffmann sign and clonus](https://durgical.com/en/clinical-exam/hoffmann-sign-and-clonus/)
- [Upper vs lower motor neuron syndrome](https://durgical.com/en/clinical-exam/upper-vs-lower-motor-neuron-syndrome/)
- [Motor examination: bulk, tone and strength grading](https://durgical.com/en/clinical-exam/motor-examination-bulk-tone-and-strength-grading/)

## Related conditions

- [Cervical radiculopathy](https://durgical.com/en/conditions/cervical-radiculopathy/)
- [Lumbar Disc Herniation](https://durgical.com/en/conditions/lumbar-disc-herniation/)
- [Guillain-Barré syndrome](https://durgical.com/en/conditions/guillain-barre-syndrome/)
- [Peripheral neuropathy (diabetic and other)](https://durgical.com/en/conditions/peripheral-neuropathy/)
- [Spinal cord injury](https://durgical.com/en/conditions/spinal-cord-injury/)

[← All of the clinical exam](https://durgical.com/en/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](https://www.msdmanuals.com/professional/neurologic-disorders/neurologic-examination/how-to-assess-reflexes) (MSD Manual Professional Edition, 2024); [26.2 Physical Assessment - Clinical Nursing Skills](https://openstax.org/books/clinical-nursing-skills/pages/26-2-physical-assessment) (OpenStax, 2024); [16.4 The Sensory and Motor Exams](https://openstax.org/books/anatomy-and-physiology-2e/pages/16-4-the-sensory-and-motor-exams) (OpenStax, Anatomy and Physiology 2e, 2022).

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License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/clinical-exam/deep-tendon-reflexes-and-their-grading/