biology

Pyramidal signs

Pyramidal signs 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 Pyramidal signs rather than just read about it. In short: Pyramidal signs indicate that the pyramidal tract is affected at some point in its course. Pyramidal tract dysfunction can lead to various clinical presentations such as spasticity, weakness, slowing of rapid alternating movements, hyperreflexia, and a positive Babinski sign.

Key takeaways

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

Reference excerpt

Pyramidal signs indicate that the pyramidal tract is affected at some point in its course. Pyramidal tract dysfunction can lead to various clinical presentations such as spasticity, weakness, slowing of rapid alternating movements, hyperreflexia, and a positive Babinski sign. The pyramidal tract completes development and myelinization between 2 and 3 years of age. Pyramidal signs occur as a normal phenomena until the age of 2, when the myelinization is finished, and so under this age they aren't considered pathological.

Pathophysiology The upper motor neurons from the central nervous system descend through the pyramidal tracts (i.e., corticospinal tracts), connecting the brain and spinal cord and help in controlling voluntary movement of muscles.

Irritative phenomena on the upper extremity

The irritative phenomena are present if there is visible flection of the thumb, which goes to opposition:

Hoffmann's sign – The patient's middle finger is flicked from the nail side down using the examiners index finger. (see video) Tromner's sign - The patient's middle finger is flicked from underneath using the examiner's index finger. (see video) Juster's sign – A sharp implement is pricked into the hypothenar eminence.

Irritative phenomena on the lower extremity

Extension Extension phenomena are positive if the great toe dorsiflexes (goes up) following the stimulus:

Babinski reflex: The plantar aspect of the foot is gently stimulated in a line starting a few centimeters distal to the heel and extended to a point just behind the toes, and then turned medially across the transverse arch. This is done slowly over 5-6 seconds. Roche's sign: Similar to Babinski but done on the external part of the foot. Chaddock's phenomen: Reaction on sharp irritation on the outer ankle. Vitek's sign: Repeatedly scrape the tip of big toe. Oppenheim's phenomen: The periosteum of tibia is irritated with the examiners knuckles. (see video) Schäffer's phenomen: The Achilles tendon is kneaded. Gordon's phenomen: The triceps surae muscle is kneaded.

Flexion These phenomena are positive if the toes of the foot flex:

Rossolimo – The ball of the foot is struck using a tendon hammer. (see video)

Clinical significance Pyramidal signs can be a result from different types of damage to the brain or spinal cord, such as strokes, infections, tumors, hemorrhagic events, multiple sclerosis, or trauma. Parkinsonian-Pyramidal syndrome (PPS) is a combination of both pyramidal and parkinsonian signs that manifest in various neurodegenerative diseases.

See also Motor neurons Amyotrophic Lateral Sclerosis Reflexes

References

External links Babinski sign "Abnormal pyramidal signs (Concept Id: C0234132) - MedGen - NCBI". www.ncbi.nlm.nih.gov. Lohia, Akash; McKenzie, Juanette (January 2020). Neuroanatomy, Pyramidal Tract Lesions. Treasure Island (FL): StatPearls Publishing. PMID 31082020. Retrieved 9 September 2020.

Further reading Nevšímaová, Růžička, Tichý (2005), Neurologie (book), yes (1st ed.), Galén, ISBN 80-7262-160-2{{citation}}: CS1 maint: multiple names: authors list (link) Jedlička, Keller (2005), Speciální neurologie (book), yes (1st ed.), Galén, ISBN 80-7262-312-5 Ambler (2011), Základy neurologie (book) (7th ed.), Galén, ISBN 978-80-7262-707-3

Worked examples

Example 1 — a first encounter with Pyramidal signs

Start with the simplest possible case. Write down what Pyramidal signs 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 Pyramidal signs 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 Pyramidal signs 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 Pyramidal signs

In research: Pyramidal signs 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 Pyramidal signs 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: Pyramidal signs is common in secondary-school and first-year university syllabi. It links to neighbouring topics Central nervous system pathways, Motor system, Neurology, so understanding it makes those chapters shorter.
In everyday life: Look for Pyramidal signs 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 Pyramidal signs in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Pyramidal signs 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 Pyramidal signs out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Pyramidal signs in simple terms?

Why does Pyramidal signs 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 Pyramidal signs?

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 Pyramidal signs.