PNB 2265
PNB 2264 Exam 4 Study Questions
and Answers 2026
Cranial cavity
houses the brain
Protection of the brain
skin
cranial bones
cranial meninges
cerebrospinal fluid
Cranial meninges
provide physical protection to the brain and spinal cord
Cerebrospinal fluid
interstitial fluid of the brain
provide chemical and physical protection to the brain
Layers of the cranial meninges
1. Dura mater
2. Arachnoid mater
3. Pia mater
Dura mater
outermost layer of the meninges
made of fibrous connective tissue
PNB 2265
,PNB 2265
strongest layer of the meninges
2 layers with blood vessels in between
Arachnoid mater
middle layer of the meninges
made of epithelial tissue
CSF is located below in subarachnoid space
Pia mater
innermost layer of the meninges
made of fibrous connective tissue
CSF pathway
CSF is produced, circulated, and stored by the ventricles
CSF flows through the subarachnoid space to leave the brain
excess CSF flows into the arachnoid villi then drains into the dural venous sinuses
Ventricular system
a system of fluid-filled cavities inside the brain that produce and circulate CSF
CSF is continuous between the brain and spinal cord
1. Lateral ventricles
2. Third ventricles
3. Cerebral aqueduct
4. Fourth ventricle
5. Central canal
6. Spinal cord
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,PNB 2265
Median and lateral apertures
openings leading from the fourth ventricle to the subarachnoid space outside of the
brain
CSF can flow through here to be circulated to the rest of the brain
CSF flow from subarachnoid space to venous blood
occurs by bulk flow - the subarachnoid space is at a higher pressure than veins so CSF
flows along its pressure gradient into the blood
Spinal tap
a sampling of CSF from the spinal cord
CSF is continuous so the concentration should be relatively the same in the spinal cord
and brain
Bulk flow
CSF is subarachnoid space flows into venous blood of the brain
Ependymal cells
found in the choroid plexus of the ventricles
epithelial cells that are selective about what passes from the blood to the CSF
produce a majority of CSF
produce about 70% of CSF
Blood vs CSF
different solute concentrations allow for formation of membrane potentials and action
potential propagation
Blood supply to the brain
1. Internal carotid arteries (anterior and medial)
PNB 2265
, PNB 2265
2. Vertebral artery (posterior)
3. Circle of Willis
Circle of Willis
redundant/overlapping of vessels that permits blood rerouting in the event of a
blockage
only prevents against damage of blood clots inside the brain
Blood return to the body
jugular vein
Ischemia
damage due to lack of blood supply to the brain
Metabolic needs of the brain
oxygen and glucose
Oxygen
passes freely across BBB
brain receives 15% of blood pumped by heart at rest
Glucose
brain consumes half of the body's glucose
membrane transporters move glucose from plasma into the CSF
Hypoglycemia
low blood sugar
leads to confusion, unconsciousness, and death
PNB 2265
PNB 2264 Exam 4 Study Questions
and Answers 2026
Cranial cavity
houses the brain
Protection of the brain
skin
cranial bones
cranial meninges
cerebrospinal fluid
Cranial meninges
provide physical protection to the brain and spinal cord
Cerebrospinal fluid
interstitial fluid of the brain
provide chemical and physical protection to the brain
Layers of the cranial meninges
1. Dura mater
2. Arachnoid mater
3. Pia mater
Dura mater
outermost layer of the meninges
made of fibrous connective tissue
PNB 2265
,PNB 2265
strongest layer of the meninges
2 layers with blood vessels in between
Arachnoid mater
middle layer of the meninges
made of epithelial tissue
CSF is located below in subarachnoid space
Pia mater
innermost layer of the meninges
made of fibrous connective tissue
CSF pathway
CSF is produced, circulated, and stored by the ventricles
CSF flows through the subarachnoid space to leave the brain
excess CSF flows into the arachnoid villi then drains into the dural venous sinuses
Ventricular system
a system of fluid-filled cavities inside the brain that produce and circulate CSF
CSF is continuous between the brain and spinal cord
1. Lateral ventricles
2. Third ventricles
3. Cerebral aqueduct
4. Fourth ventricle
5. Central canal
6. Spinal cord
PNB 2265
,PNB 2265
Median and lateral apertures
openings leading from the fourth ventricle to the subarachnoid space outside of the
brain
CSF can flow through here to be circulated to the rest of the brain
CSF flow from subarachnoid space to venous blood
occurs by bulk flow - the subarachnoid space is at a higher pressure than veins so CSF
flows along its pressure gradient into the blood
Spinal tap
a sampling of CSF from the spinal cord
CSF is continuous so the concentration should be relatively the same in the spinal cord
and brain
Bulk flow
CSF is subarachnoid space flows into venous blood of the brain
Ependymal cells
found in the choroid plexus of the ventricles
epithelial cells that are selective about what passes from the blood to the CSF
produce a majority of CSF
produce about 70% of CSF
Blood vs CSF
different solute concentrations allow for formation of membrane potentials and action
potential propagation
Blood supply to the brain
1. Internal carotid arteries (anterior and medial)
PNB 2265
, PNB 2265
2. Vertebral artery (posterior)
3. Circle of Willis
Circle of Willis
redundant/overlapping of vessels that permits blood rerouting in the event of a
blockage
only prevents against damage of blood clots inside the brain
Blood return to the body
jugular vein
Ischemia
damage due to lack of blood supply to the brain
Metabolic needs of the brain
oxygen and glucose
Oxygen
passes freely across BBB
brain receives 15% of blood pumped by heart at rest
Glucose
brain consumes half of the body's glucose
membrane transporters move glucose from plasma into the CSF
Hypoglycemia
low blood sugar
leads to confusion, unconsciousness, and death
PNB 2265
