Development Of CNS, Meninges, CSF and blood supply

Question 1

The nervous system develops from which layer of the embryo?

Answer 1

Ectoderm

Becomes neuroectoderm

Question 2

What are the stages of embryology of the CNS?

Answer 2

Ectoderm thickens to become the neural plate
Neural plate invaginate to become neural groove, with neural folds at the top. Below neural plate is notochord which secretes chemicals to stimulate development
Neural folds fuse and neural plate becomes neural tube

Question 3

The PNS is formed from which cells?

Answer 3

Neural crest cells

Question 4

Which parts of the neural tube form what?

Answer 4

Dorsal - alar plate

Ventral tube - basal plate

Question 5

What are the meninges?

Answer 5

Membranes of the brain and spinal cord (continuous)

Question 6

What are the 3 layers of the meninges? Out to in

Answer 6

Dura mater
Arachnoid
Pia mater

Question 7

What is the function of the meninges?

Answer 7

Provide framework for blood supply
Protection
Flow of CSF

Question 8

The Dura mater is made of 2 layers in the skull. What are these layers called?

Answer 8

Outer - endosteal

inner - meningeal

Question 9

Does the dura mater have its own blood supply? What does the dura mater contain?

Answer 9

yes

Venous sinuses

Question 10

What is the arachnoid? What are the spaces either side of the arachnoid?

Answer 10

Avascular membrane
Space between dura mater and arachnoid - potential space
Space between arachnoid and pia mater - actual space - subarachnoid space

Question 11

What is the pia mater?

Answer 11

Inner most meninge layer
Highly vascular
Like visceral pleura

Question 12

What are cuff zones? What is the clinical signifcance of this?

Answer 12

Where meninges join with nerves

Good for anaesthesia

Question 13

What is the epidural space? What does it contain?

Answer 13

Space between the vertebrae and dura mater

Fat and blood vessels

Question 14

Where is cerebral spinal fluid?

Answer 14

in the subarachnoid space, ventricles of the brain and central spinal cord

Question 15

What is the function of CSF?

Answer 15

Shock absorption

Nutrition to nervous tissue

Question 16

Describe the composition of CSF

Answer 16

No cells or proteins 
Stable
Little AAs and potassium ( prevent firing APs)
Low glucose
Communicate freely with ISF

Question 17

the ventricles and central spinal cord are linked by which cells? What is their function?

Answer 17

Ependymal cells (with cilia)
Allow transport of CSF

Question 18

What are the sources of CSF?

Answer 18

Main - choroid plexus (group of ependymal cells in ventricles of the brain)
Minor — ultrafiltrate of pial (surface of brain) blood

Question 19

What maintains the concentration and osmolarity of CSF? How does it do this?

Answer 19

Blood brain barrier

Ependymal cells pump solutes into CSF, cause water to be drawn out by osmosis

Question 20

When taking a sample of CSF, where do you take it?

Answer 20

Widening of subarachnoid space

Behind neck

Question 21

Why is the AA content in CSF low?

Answer 21

Some are neurotransmitters, prevent firing of action potentials

Question 22

What provides blood supply to the brain?

Answer 22

Cerebroarterial circle

Question 23

What are the 5 pairs of arteries that supply blood to the cerebroarterial circle?

Answer 23

Rostral cerebral
Middle cerebral
Dorsal cerebral
Rostral cerebellar
Internal carotid arteries

Question 24

Which blood vessels supply the cerebroarterial circle with blood?

Answer 24

Dog/horse - basilar artery
Sheep/cat - maxillary artery
Ox - maxillary and vertebral artery

Question 25

What are the rete mirabile?

Answer 25

Net of blood vessels to the brain which cool down and reduce the pressure of blood

Question 26

Which blood vessels supply the spinal cord?

Answer 26

Vertebral arteries and aorta