Neuroanatomy - Blood supply + ventricular system

Question 1

Which arteries does the brain receive blood from?

Answer 1

• Internal carotid arteries
• Vertebral arteries

Question 2

Describe the internal carotid arteries

Answer 2

• Common carotids bifurcate into internal and external
• External supplies the face, scalp, neck, etc
• Internal supplies the brain
• Enters brain via carotid canals

Question 3

Describe the vertebral arteries

Answer 3

• Branch of the subclavian arteries
• Ascends in the neck through the transverse foramen of the cervical vertebrae
• Enters skull via foramen magnum
• Vertebral arteries fuse at base of brainstem to form the basilar artery

Question 4

What are the 3 pairs of cerebral arteries

Answer 4

• Posterior cerebral artery
• Middle cerebral artery
• Anterior cerebral artery

Question 5

What are the 3 pairs of cerebellar arteries

Answer 5

• Posterior inferior cerebellar arteries
• Anterior inferior cerebellar arteries
• Superior cerebellar arteries

Question 6

What is the arterial circle of willis

Answer 6

• Interconnects the internal carotid and vertebral-basilar system
• Surrounds the optic chiasma and hypothalamus
• Ensures compensation of decreased blood flow If one blood vessel is blocked

Question 7

What are aneurysms

Answer 7

• Abnormal dilations around the circle of Willis or at points of arterial branching in the brain
• ~ 10% of vascular strokes are caused by rupture of a berry aneurysm

Question 8

What is the role of the arterial circle

Answer 8

Each cerebral artery supplies a different cerebral hemisphere:
- Anterior cerebral artery - supplies the superior and medial areas of frontal and parietal lobes; supplies the corpus callosum
- Middle cerebral artery - Supplies the lateral areas of the frontal, temporal, and parietal lobes
- Posterior cerebral artery - Supplies the inferior and medial surface of the temporal lobe and the occipital lobe
- Deep arteries and striate arteries supply hemispherical structures

Question 9

Describe venous drainage of the blood

Answer 9

• All venous blood from the brain drains into the internal jugular veins
• Dural sinuses receive venous blood from the brain and drain directly into the internal jugular
  veins respectively
• Transverse sinuses transfer blood into the sigmoid sinuses, then the internal jugular
  vein

Question 10

What are the 3 meningeal coverings that surround the CNS and spinal cord

Answer 10

• Dura mater
• Arachnoid mater
• Pia mater

Question 11

How many layers of dura mater are there?
What do they allow for?
What do they form?

Answer 11

• 2
• Allow for dural infoldings at specific areas
• Form dural sinuses

Question 12

Describe damage to the dura

Answer 12

• Falx cerebri: a supportive layer that sits between cerebral hemispheres
• Tentorium cerebelli: between occipital lobes and the cerebellum
• Venous dural sinuses lie between dural infoldings

Question 13

What is the ventricular system?

Answer 13

A series of interconnecting chambers throughout the CNS are present, all derived from the lumen of the neural tube

Question 14

What are ventricles

Answer 14

Dilations from the central canal containing choroid plexus → Cerebrospinal fluid

Question 15

How many ventricles are there?

Answer 15

4 ventricles:
- 2 lateral ventricles,
- 3rd ventricle between the thalami
- 4th ventricle lies between the pons (anteriorly) and the cerebellum (posteriorly)

Question 16

How is the brain formed

Answer 16

Due to the enormous growth and distortion of an elaborate system of ventricles

Question 17

What is cerebrospinal fluid

Answer 17

A clear, colourless, blood derived fluid that contains glucose and inorganic salts

Question 18

What does cerebrospinal fluid consist of

Answer 18

• Little protein
• Very few cells

Question 19

Where is the cerebrospinal fluid produced

Answer 19

Produced in the ventricles by specialised areas of ventricular lining: choroid plexus

Question 20

What does cerebrospinal fluid provide

Answer 20

• Physical protection for the CNS
• Chemical stability for the CNS

Question 21

What are arachnoid villi

Answer 21

Extensions of arachnoid matter into dural sinuses predominantly into the superior sagittal sinus

Question 22

What are the rules of cerebrospinal fluid

Answer 22

• Buoyancy:reducetraction
• Cushioning: dampen trauma
• Transport substances: nutrients, dissolved gases, and the removal of metabolites
• Provides a stable environment

Question 23

What happens if cerebrospinal fluid flow is blocked

Answer 23

The fluid accumulates upstream of the blockage, leading to a condition called hydrocephalus