Chapter 3

Question 1

Name the three meningeal layers from superficial to deep.

Answer 1

Dura mater → arachnoid mater → pia mater.

Question 2

What two layers form the cranial dura?

Answer 2

Periosteal layer, meningeal layer.

Question 3

Real vs potential epidural space—brain vs spinal cord?

Answer 3

Brain: potential only; Spinal cord: real space with fat & veins.

Question 4

Which dural reflection separates cerebral hemispheres?

Answer 4

Falx cerebri.

Question 5

Largest subarachnoid cistern & its location.

Answer 5

Cisterna magna (cerebellomedullary cistern) between cerebellum & medulla.

Question 6

Structures passing through tentorial notch.

Answer 6

Midbrain, upper brainstem.

Question 7

Two reasons lumbar cistern (L2–S2) is ideal for CSF tap.

Answer 7

Wide sub‑arachnoid space, no spinal cord, only cauda equina.

Question 8

Adult vs child lumbar puncture levels.

Answer 8

Adults: L3‑L4; Children: L4‑L5.

Question 9

Normal adult CSF pressure (recumbent).

Answer 9

100–150 mm H₂O (< 200 mm H₂O).

Question 10

Main CSF producer & daily volume.

Answer 10

Choroid plexus; ≈ 500 mL/day.

Question 11

Explain CSF one‑way flow through arachnoid villi.

Answer 11

Subarachnoid pressure (~200 mm H₂O) > venous sinus pressure (~80 mm H₂O); villous tubules collapse if reverse gradient.

Question 12

Where does CSF exit the 4th ventricle?

Answer 12

Foramina of Luschka (laterals), Magendie (midline).

Question 13

Four cardinal functions of CSF.

Answer 13

• Buoyancy
• Cushioning
• Waste removal
• Ionic homeostasis

Question 14

CSF glucose pattern in bacterial vs viral meningitis.

Answer 14

Bacterial ↓; Viral normal.

Question 15

Non‑communicating hydrocephalus example obstruction site.

Answer 15

Cerebral aqueduct (aqueductal stenosis).

Question 16

Clinical triad of normal‑pressure hydrocephalus.

Answer 16

• Gait apraxia (wobbly)
• Urinary incontinence (wet)
• Dementia (weird)

Question 17

Blood‑brain barrier cellular component providing tight junctions.

Answer 17

Capillary endothelial cells.

Question 18

Give two circumventricular organs lacking BBB.

Answer 18

• Area postrema
• Subfornical organ

Question 19

Role of denticulate ligaments.

Answer 19

Anchor spinal cord laterally to dura/arachnoid.

Question 20

Filum terminale internum vs externum composition.

Answer 20

Internum: pia + glial cells; Externum: dura continuation anchoring to coccyx.

Question 21

CSF protein content relative to serum?

Answer 21

Much lower (≈ 0.3 g/L vs 60–70 g/L).

Question 22

Which meningeal layer is pain‑sensitive & vascular?

Answer 22

Periosteal dura mater.

Question 23

Bacterial meningitis CSF cell predominance.

Answer 23

Polymorphonuclear leukocytes (neutrophils).

Question 24

Cause of papilledema in raised ICP.

Answer 24

Elevated subarachnoid pressure transmitted along optic nerve sheath → optic disc swelling.

Question 25

Hydrocephalus ex vacuo—mechanism.

Answer 25

Ventricular enlargement secondary to brain tissue loss (e.g., stroke, degeneration).

Question 26

Typical adult total CSF volume in ventricles.

Answer 26

~23 mL.

Question 27

Function of arachnoid trabeculae.

Answer 27

Suspend brain within CSF, limiting displacement.

Question 28

Why are tight junctions absent in choroidal capillaries?

Answer 28

Fenestrations allow plasma filtrate; barrier instead at choroidal epithelial layer.

Question 29

Which meningeal tumor type shows chromosome 22 deletion?

Answer 29

Meningioma.

Question 30

List two signs contra‑indicating immediate lumbar puncture.

Answer 30

* Marked papilledema * Focal neurological signs suggesting mass effect (risk of herniation)