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Internal auditory meatus

Internal auditory meatus is a science 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 Internal auditory meatus rather than just read about it. In short: The internal auditory meatus (also meatus acusticus internus, internal acoustic meatus, internal auditory canal, or internal acoustic canal) is a canal within the petrous part of the temporal bone of the skull between the posterior cranial fossa and the inner ear. Structure The opening to the meatus is called the porus acusticus internus or internal acoustic opening.

Internal auditory meatus — main illustration
Internal auditory meatus — illustration

Key takeaways

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

Reference excerpt

The internal auditory meatus (also meatus acusticus internus, internal acoustic meatus, internal auditory canal, or internal acoustic canal) is a canal within the petrous part of the temporal bone of the skull between the posterior cranial fossa and the inner ear.

Structure The opening to the meatus is called the porus acusticus internus or internal acoustic opening. It is located inside the posterior cranial fossa of the skull, near the center of the posterior surface of the petrous part of the temporal bone. The size varies considerably. Its outer margins are smooth and rounded. The canal which comprises the internal auditory meatus is short (about 1 cm) and runs laterally into the bone. The lateral (outer) aspect of the canal is known as the fundus. The fundus is subdivided by two thin crests of bone to form three separate canals, through which course the facial and vestibulocochlear nerve branches. The falciform crest first divides the meatus into superior and inferior sections; a vertical crest (Bill's bar, named by William F. House) then divides the upper passage into anterior and posterior sections. Although there are three osseous canals, the fundus is conceptually divided more commonly into four quadrant areas according to the four major nerve branches of the inner ear:

anterior superior - facial nerve area (contains facial nerve and nervus intermedius) anterior inferior - cochlear nerve area (contains cochlear nerve) posterior superior - superior vestibular area (contains superior division of vestibular nerve) posterior inferior - inferior vestibular area (contains inferior division of vestibular nerve) The cochlear and vestibular branches of cranial nerve VIII separate according to this schema and terminate in the inner ear. The facial nerve continues traveling through the facial canal, eventually exiting the skull at the stylomastoid foramen. A common mnemonic to remember the anterior quadrants of the inner ear is: "seven up, coke down" (seventh nerve superior, cochlear nerve inferior).

Function The internal auditory meatus provides a passage through which the vestibulocochlear nerve (CN VIII), the facial nerve (CN VII), and the labyrinthine artery (an internal auditory branch of the anterior inferior cerebellar artery in 85% of people) can pass from inside the skull to structures of the inner ear and face. It also contains the vestibular ganglion.

Additional images

See also External auditory meatus

References This article incorporates text in the public domain from page 143 of the 20th edition of Gray's Anatomy (1918)

External links Anatomy figure: 30:01-08 at Human Anatomy Online, SUNY Downstate Medical Center cranialnerves at The Anatomy Lesson by Wesley Norman (Georgetown University) (VII) Diagram of Porus acusticus internus Diagram of Porus acusticus internus

Illustrations

Internal auditory meatus illustration
Internal auditory meatus illustration
Internal auditory meatus illustration
Internal auditory meatus illustration
Internal auditory meatus illustration

Worked examples

Example 1 — a first encounter with Internal auditory meatus

Start with the simplest possible case. Write down what Internal auditory meatus claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, 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 Internal auditory meatus 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 Internal auditory meatus 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 Internal auditory meatus

In research
Internal auditory meatus appears in science 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 Internal auditory meatus 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
Internal auditory meatus is common in secondary-school and first-year university syllabi. It links to neighbouring topics Foramina of the skull, Otology, Otorhinolaryngology, so understanding it makes those chapters shorter.
In everyday life
Look for Internal auditory meatus 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 Internal auditory meatus in 20 minutes

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

Frequently asked questions

What is Internal auditory meatus in simple terms?

The internal auditory meatus (also meatus acusticus internus, internal acoustic meatus, internal auditory canal, or internal acoustic canal) is a canal within the petrous part of the temporal bone of the skull between the posterior cranial fossa and the inner ear. Structure The opening to the meatu…

Why does Internal auditory meatus matter?

Because it connects several science 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 Internal auditory meatus?

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 Internal auditory meatus.

Tags

  • Foramina of the skull
  • Otology
  • Otorhinolaryngology

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