CSF system Flashcards by Nihal Afsheen

What is CSF?

• Cerebrospinal fluid — a clear fluid that surrounds the brain and spinal cord

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Why does the brain need CSF?

• Cushions the brain 🛟
• Protects it from injury
• Nourishes it
• Removes waste

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Where is CSF found?

• Inside the ventricles
• Around the brain and spinal cord
• In the subarachnoid space

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What are ventricles?

• Fluid-filled spaces inside the brain

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How many ventricles are there?

• 👉 Four ventricles

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Name the four ventricles.

1️⃣ Right lateral ventricle
2️⃣ Left lateral ventricle
3️⃣ Third ventricle
4️⃣ Fourth ventricle

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Where are the lateral ventricles located?

• 👉 One in each cerebral hemisphere

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Where is the third ventricle located?

• 👉 In the midline, between the two thalami

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Where is the fourth ventricle located?

• 👉 Between the brainstem and the cerebellum

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How do the lateral ventricles connect to the third ventricle?

• Through the interventricular foramina (foramina of Monro)

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How does the third ventricle connect to the fourth ventricle?

• Through the cerebral aqueduct

📌 Narrow — blockage causes hydrocephalus (exam favourite)

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Where is CSF produced?

• 👉 By the choroid plexus

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What is the choroid plexus?

• A specialised capillary + ependymal cell structure that makes CSF

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In which ventricles is CSF produced?

• Mainly lateral ventricles
• Also third & fourth ventricles

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What is the order of CSF flow?

• Lateral ventricles
⬇️
• Third ventricle
⬇️
• Fourth ventricle
⬇️
• Subarachnoid space
⬇️
• Venous system

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How does CSF leave the fourth ventricle?

• Through the median aperture
• Through the lateral apertures
• 👉 Into the subarachnoid space

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What is the subarachnoid space?

• The space between:
• Arachnoid mater
• Pia mater

📌 CSF circulates here around the brain & spinal cord

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Where is CSF absorbed?

• 👉 At the arachnoid granulations

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What do arachnoid granulations do?

• Allow CSF to drain into venous blood

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What happens if CSF absorption is impaired?

• 👉 Hydrocephalus (raised CSF pressure)

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What cells line the ventricles?

• 👉 Ependymal cells

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What do ependymal cells do?

• Line ventricles
• Help produce & circulate CSF

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Is CSF produced in the subarachnoid space?

Study These Flashcards

• ❌ No — CSF is produced in the ventricles

Does CSF flow backwards?

Study These Flashcards

• ❌ No — CSF flow is one direction only

**Is the cerebral aqueduct wide?**

• ❌ **No** — it is **very narrow** (high blockage risk)

**Easy way to remember CSF flow?**

• 🧠 **“L-3-4-S-V”** • Lateral • 3rd • 4th • Subarachnoid • Venous blood

**What are the 6 must-remember facts about CSF & ventricles?**

1️⃣ CSF cushions & protects the brain 2️⃣ Made by **choroid plexus** 3️⃣ Flows **lateral → 3rd → 4th** 4️⃣ Enters **subarachnoid space** 5️⃣ Absorbed at **arachnoid granulations** 6️⃣ Blockage → **hydrocephalus**

**What is hydrocephalus?**

• A condition where there is **too much CSF in the brain** • Causes **ventricular enlargement** • Often causes **raised intracranial pressure**

**What are the TWO main types of hydrocephalus?**

1️⃣ **Communicating hydrocephalus** 2️⃣ **Non-communicating (obstructive) hydrocephalus**

**What is communicating hydrocephalus?**

• CSF **CAN flow between ventricles** • Ventricles are still **connected (communicating)**

**Where is the problem in communicating hydrocephalus?**

• ❌ NOT a ventricular blockage • 👉 Problem is **impaired CSF absorption**

**Which structure fails in communicating hydrocephalus?**

• **Arachnoid granulations** • CSF is made normally but **not absorbed properly**

**What happens to the ventricles in communicating hydrocephalus?**

• 👉 **ALL ventricles enlarge**

**Common causes of communicating hydrocephalus?**

• **Subarachnoid haemorrhage** • **Meningitis** • Scarring/fibrosis of arachnoid granulations

**One-line exam definition of communicating hydrocephalus?**

• **Impaired CSF absorption with no ventricular blockage**

**What is non-communicating (obstructive) hydrocephalus?**

• Hydrocephalus caused by a **BLOCKAGE within the ventricular system**

**What does “non-communicating” mean?**

• Ventricles **cannot communicate normally** • CSF flow is **blocked**

**Where is the blockage in non-communicating hydrocephalus?**

• **Inside the ventricular system** • Most commonly at the **cerebral aqueduct**

**Why is the cerebral aqueduct a common blockage site?**

• It is **very narrow** • Easily blocked by tumours or congenital stenosis

**What happens to ventricles in non-communicating hydrocephalus?**

• **Only ventricles BEFORE the blockage enlarge** • Ventricles after blockage are normal or small

**Give a classic cause of non-communicating hydrocephalus.**

• **Aqueductal stenosis**

**Other causes of non-communicating hydrocephalus?**

• Brain tumours • Congenital malformations • Cysts

**One-line exam definition of non-communicating hydrocephalus?**

• **CSF flow blocked within the ventricles**

**Key difference between communicating and non-communicating hydrocephalus?**

• **Communicating** → absorption problem, all ventricles enlarge • **Non-communicating** → blockage, only upstream ventricles enlarge

**Is communicating hydrocephalus caused by aqueduct blockage?**

• ❌ **No** — aqueduct blockage causes **non-communicating** hydrocephalus

**Do all ventricles enlarge in non-communicating hydrocephalus?**

• ❌ **No** — only those **before the blockage**

**What is normal pressure hydrocephalus (NPH)?**

• A type of **communicating hydrocephalus** • Ventricles are enlarged • CSF pressure is **normal or intermittently raised**

**What is the core problem in normal pressure hydrocephalus?**

• **Impaired CSF absorption** at arachnoid granulations

**Which ventricles enlarge in normal pressure hydrocephalus?**

• **All ventricles** enlarge (communicating type)

**Classic triad of normal pressure hydrocephalus?**

• **Gait disturbance** 🚶 • **Urinary incontinence** 🚽 • **Cognitive impairment (dementia)** 🧠 📌 Exam phrase: **“Wet, wobbly, and wacky”**

**Which symptom usually appears FIRST in NPH?**

• **Gait disturbance** (magnetic, shuffling gait)

**How does CSF pressure appear in NPH lumbar puncture?**

• Often **normal**

**Why is NPH important for exams?**

• It is a **reversible cause of dementia** • Treatable with **CSF shunting**

**Easy memory trick for hydrocephalus types?**

• **C = Communicating = absorption problem** • **N = Non-communicating = Narrowed/blocked** • **NPH = Normal pressure + gait first**

**5 must-remember exam facts about hydrocephalus?**

"1️⃣ Hydrocephalus = excess CSF 2️⃣ Communicating = **absorption problem** 3️⃣ Non-communicating = **ventricular blockage** 4️⃣ Aqueduct stenosis = classic obstructive cause 5️⃣ **NPH triad: gait, incontinence, dementia**

CSF system Flashcards

(55 cards)