biology

Mastoid cells

Mastoid cells 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 Mastoid cells rather than just read about it. In short: The mastoid cells (also called air cells of Lenoir or mastoid cells of Lenoir) are air-filled cavities within the mastoid process of the temporal bone of the cranium. The mastoid cells are a form of skeletal pneumaticity.

Key takeaways

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

Reference excerpt

The mastoid cells (also called air cells of Lenoir or mastoid cells of Lenoir) are air-filled cavities within the mastoid process of the temporal bone of the cranium. The mastoid cells are a form of skeletal pneumaticity. Infection in these cells is called mastoiditis. The term cells here refers to enclosed spaces, not cells as living biological units.

Anatomy

The mastoid air cells vary greatly in number, shape, and size; they may be extensive or minimal or even absent. The cells are typically interconnected and their walls lined by mucosa that is continuous with that of the mastoid antrum and tympanic cavity.

Extent

They may excavate the mastoid process to its tip, and be separated from the posterior cranial fossa and sigmoid sinus by a mere slip of bone or not at all. They may extend into the squamous part of temporal bone, petrous part of the temporal bone zygomatic process of temporal bone, and - rarely - the jugular process of occipital bone; they may thus come to adjoin many important structures (including the bony labyrinth, tympanic cavity, external acoustic meatus, pharyngotympanic tube, superior jugular bulb, posterior cranial fossa, middle cranial fossa, carotid canal, abducens nerve, sigmoid sinus) to which they may disseminate infection in case of infective mastoiditis.

Innervation The cells receive innervation from the posterior branch of the meningeal branch of the mandibular nerve (nervus spinosus), and branches of the tympanic plexus.

Vasculature The cells receive arterial supply from the stylomastoid branch of the occipital artery or posterior auricular artery, and (sometimes) a mastoid branch of the occipital artery. The superior petrosal sinus receives venous drainage from the mastoid air cells (mastoid infection may thus lead to a cerebellar abscess).

Development At birth, the mastoid is not pneumatized, but becomes aerated before age six. At birth, the mastoid antrum is well developed but the air cells are represented only by small diverticula from the antrum. The air cells then gradually extend into the bone of the mastoid during the first years of life. Their most significant enlargements takes place during puberty.

Function The air cells are hypothesised to protect the temporal bone and the inner and middle ear against trauma and to regulate air pressure.

Clinical significance Infections in the middle ear easily spread into the mastoid air cells through the aditus ad antrum, resulting in mastoiditis, a potentially dangerous and life-threatening condition. Infection may then further spread into the middle cranial fossa or posterior cranial fossa, causing meningitis or abscess of adjacent brain tissue. Infection may also spread to muscles of the neck, causing pain and torticollis.

References

External links

Anatomy image: hn1-8 at the College of Medicine at SUNY Upstate Medical University

Illustrations

Worked examples

Example 1 — a first encounter with Mastoid cells

Start with the simplest possible case. Write down what Mastoid cells 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 Mastoid cells 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 Mastoid cells 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 Mastoid cells

In research: Mastoid cells 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 Mastoid cells 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: Mastoid cells is common in secondary-school and first-year university syllabi. It links to neighbouring topics Bones of the head and neck, Ear, Human head and neck, so understanding it makes those chapters shorter.
In everyday life: Look for Mastoid cells 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 Mastoid cells in 20 minutes

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

Frequently asked questions

What is Mastoid cells in simple terms?

Why does Mastoid cells 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 Mastoid cells?

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 Mastoid cells.