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Palpebral fissure

Palpebral fissure 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 Palpebral fissure rather than just read about it. In short: The palpebral fissure is the elliptic space between the medial and lateral canthi of the two open eyelids. In simple terms, it is the opening between the eyelids.

Palpebral fissure — main illustration
Palpebral fissure — illustration

Key takeaways

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

Reference excerpt

The palpebral fissure is the elliptic space between the medial and lateral canthi of the two open eyelids. In simple terms, it is the opening between the eyelids. In adult humans, this measures about 10 mm vertically and 30 mm horizontally.

Variations

Congenital dysmorphisms It can be reduced (short, "narrow") in horizontal size by fetal alcohol syndrome and in Williams syndrome. The chromosomal conditions trisomy 9 and trisomy 21 (Down syndrome) can cause the palpebral fissures to be upslanted, whereas Marfan syndrome can cause a downslant. An increase in vertical height can be seen in genetic disorders such as cri-du-chat syndrome.

Acquired The fissure may be increased in vertical height in Graves' disease, which is manifested as Dalrymple's sign. It is seen in disorders such as cri-du-chat syndrome. In animal studies using four times the therapeutic concentration of the ophthalmic solution latanoprost, the size of the palpebral fissure can be increased. The condition is reversible. Latanoprost is a prostaglandin F receptor agonist.

See also Blepharophimosis

References

External links Facial Neurological Examination Archived 2012-10-08 at the Wayback Machine from University of Toronto

Illustrations

Palpebral fissure illustration

Worked examples

Example 1 — a first encounter with Palpebral fissure

Start with the simplest possible case. Write down what Palpebral fissure 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 Palpebral fissure 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 Palpebral fissure 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 Palpebral fissure

In research
Palpebral fissure 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 Palpebral fissure 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
Palpebral fissure is common in secondary-school and first-year university syllabi. It links to neighbouring topics Human eye anatomy, so understanding it makes those chapters shorter.
In everyday life
Look for Palpebral fissure 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 Palpebral fissure in 20 minutes

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

Frequently asked questions

What is Palpebral fissure in simple terms?

The palpebral fissure is the elliptic space between the medial and lateral canthi of the two open eyelids. In simple terms, it is the opening between the eyelids.

Why does Palpebral fissure 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 Palpebral fissure?

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 Palpebral fissure.

Tags

  • Human eye anatomy

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