science

Posterior cranial fossa

Posterior cranial fossa 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 Posterior cranial fossa rather than just read about it. In short: The posterior cranial fossa is the part of the cranial cavity located between the foramen magnum, and tentorium cerebelli. It is formed by the sphenoid bones, temporal bones, and occipital bone.

Key takeaways

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

Reference excerpt

The posterior cranial fossa is the part of the cranial cavity located between the foramen magnum, and tentorium cerebelli. It is formed by the sphenoid bones, temporal bones, and occipital bone. It lodges the cerebellum, and parts of the brainstem.

Anatomy The posterior cranial fossa is formed by the sphenoid bones, temporal bones, and occipital bone. It is the most inferior of the fossae. It houses the cerebellum, medulla oblongata, and pons.

Boundaries Anteriorly, the posterior cranial fossa is bounded by the dorsum sellae, posterior aspect of the body of sphenoid bone, and the basilar part of occipital bone/clivus. Laterally, it is bounded by the petrous parts and mastoid parts of the temporal bones, and the lateral parts of occipital bone. Posteriorly, it is bounded by the squamous part of occipital bone.

Features

Foramen magnum

The foramen magnum is a large opening of the floor of the posterior cranial fossa, its most conspicuous feature.

Internal acoustic meatus

Lies in the anterior wall of the posterior cranial fossa. It transmits the facial (VII) and vestibulocochlear (VIII) cranial nerves into a canal in the petrous temporal bone.

Jugular foramen

Lies between the inferior edge of the petrous temporal bone and the adjacent occipital bone and transmits the internal jugular vein (actually begins here), the glossopharyngeal nerve (CN IX), vagus nerve (CN X), and accessory nerve (CN XI).

Hypoglossal canal

Lies at the anterolateral margins of the foramen magnum and transmits the hypoglossal nerve (CN XII).

Other Also visible in the posterior cranial fossa are depressions caused by the venous sinuses returning blood from the brain to the venous circulation: Right and left transverse sinuses which meet at the confluence of sinuses (marked by the internal occipital protuberance). The transverse sinuses pass horizontally from the most posterior point of the occiput. Where the apex of the petrous temporal meets the squamous temporal, the transverse sinuses lead into sigmoid (S-shaped) sinuses (one on each side). These pass along the articulation between the posterior edge of the petrous temporal bone and the anterior edge of the occipital bones to the jugular foramen, where the sigmoid sinus becomes the internal jugular vein. Note that a superior petrosal sinus enters the junction of the transverse and sigmoid sinuses. Also an inferior petrosal sinus enters the sigmoid sinus near the jugular foramen. The posterior cranial fossa is formed in the endocranium, and holds the most basal parts of the brain.

Clinical significance An underdeveloped posterior cranial fossa can cause Arnold–Chiari malformation. These can be either acquired or congenital disorders.

Additional images

See also Anterior cranial fossa Middle cranial fossa

References

External links

Anatomy photo:22:os-0803 at the SUNY Downstate Medical Center

Illustrations

Worked examples

Example 1 — a first encounter with Posterior cranial fossa

Start with the simplest possible case. Write down what Posterior cranial fossa 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 Posterior cranial fossa 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 Posterior cranial fossa 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 Posterior cranial fossa

In research: Posterior cranial fossa 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 Posterior cranial fossa 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: Posterior cranial fossa is common in secondary-school and first-year university syllabi. It links to neighbouring topics Otorhinolaryngology, Skull, so understanding it makes those chapters shorter.
In everyday life: Look for Posterior cranial fossa 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 Posterior cranial fossa in 20 minutes

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

Frequently asked questions

What is Posterior cranial fossa in simple terms?

The posterior cranial fossa is the part of the cranial cavity located between the foramen magnum, and tentorium cerebelli. It is formed by the sphenoid bones, temporal bones, and occipital bone.

Why does Posterior cranial fossa 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 Posterior cranial fossa?

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 Posterior cranial fossa.