biology

Jendrassik maneuver

Jendrassik maneuver is a biology topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Jendrassik maneuver rather than just read about it. In short: The Jendrassik maneuver is a medical maneuver wherein the patient clenches the teeth, flexes both sets of fingers into a hook-like form, and interlocks those sets of fingers together. The tendon below the patient's knee is then hit with a reflex hammer to elicit the patellar reflex.

Key takeaways

Jendrassik maneuver belongs to biology; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Jendrassik maneuver to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Jendrassik maneuver from memory before moving on to harder problems.

Reference excerpt

The Jendrassik maneuver is a medical maneuver wherein the patient clenches the teeth, flexes both sets of fingers into a hook-like form, and interlocks those sets of fingers together. The tendon below the patient's knee is then hit with a reflex hammer to elicit the patellar reflex. The elicited response is compared with the reflex result of the same action when the maneuver is not in use. Often a larger reflex response will be observed when the patient is occupied with the maneuver: "A weak or apparently missing reflex could be triggered by afferent activity resulting from such muscle tension. This is the true explanation for the maneuver, not a diversion of the patient’s attention – a misconception that can be heard even today." This effect was first observed in the late 19th century by Hungarian physician Ernő Jendrassik, after whom it was named. This maneuver is particularly useful in that even if the patient is aware of the maneuver's purpose, it still functions properly. The maneuver can also be used to distract patients when performing other tests or procedures and any suitable distraction may be used; for example when looking for Romberg's sign.

References

Further reading Niechwiej-Szwedo E, González E, Bega S, Verrier M, Wong A, Steinbach M (2006). "Proprioceptive role for palisade endings in extraocular muscles: evidence from the Jendrassik Maneuver". Vision Res. 46 (14): 2268–79. doi:10.1016/j.visres.2005.12.006. PMID 16445961. Tsuruike M, Koceja D, Yabe K, Shima N (2003). "Age comparison of H-reflex modulation with the Jendrássik maneuver and postural complexity". Clin Neurophysiol. 114 (5): 945–53. doi:10.1016/S1388-2457(03)00039-7. PMID 12738442. S2CID 24945591. Zehr E, Stein R (1999). "Interaction of the Jendrássik maneuver with segmental presynaptic inhibition". Exp Brain Res. 124 (4): 474–80. doi:10.1007/s002210050643. PMID 10090659. S2CID 6650853.

External links Diagram

Illustrations

Worked examples

Example 1 — a first encounter with Jendrassik maneuver

Start with the simplest possible case. Write down what Jendrassik maneuver claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In biology, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Jendrassik maneuver before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Jendrassik maneuver ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Jendrassik maneuver

In research: Jendrassik maneuver appears in biology research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Jendrassik maneuver in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Jendrassik maneuver is common in secondary-school and first-year university syllabi. It links to neighbouring topics Diagnostic neurology, Medical treatment stubs, Reflexes, so understanding it makes those chapters shorter.
In everyday life: Look for Jendrassik maneuver outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Jendrassik maneuver in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Jendrassik maneuver means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Jendrassik maneuver out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Jendrassik maneuver in simple terms?

Why does Jendrassik maneuver matter?

Because it connects several biology ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Jendrassik maneuver?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Jendrassik maneuver.