The Human CNS: Development & Spinal Cord

Question 1

What is the CNS formed from?

Answer 1

Neural tube

Question 2

Essentially, what is the human CNS?

Answer 2

An over-blown tube which expands during development

Question 3

How does the nervous system develop?

Answer 3

1) Starts as flat sheet of cells called the neural plate on the surface of the developing embryo
2) The neural plate starts to sink to form a neural groove
3) The edges start to rise up and fuse together. Ends called neuropores

Question 4

What is the name given to the flat sheet of cells on the surface of the developing embryo from which the nervous system develops?

Answer 4

Neural plate

Question 5

What is formed when the neural plate sinks?

Answer 5

Neural groove

Question 6

What are the ends of the neural tube called?

Answer 6

Neuropores

Question 7

Give some examples of diseases caused by neural tube defects

Answer 7

• Spina bifida

- Anencephaly

Question 8

How is spina bifida caused?

Answer 8

Failure of neural tube closure

Question 9

What is anencephaly and how is it caused?

Answer 9

Absence of a portion of the brian and it’s caused when the cranial/rostral end of the neural tube fails to close

Question 10

What end of the neural tube fails to close properly to lead to anencephaly?

Answer 10

The cranial end

Question 11

What can prevent most defects associated with the neural tube?

Answer 11

Folic acid

Question 12

What are the 3 primary brain vesicles?

Answer 12

• Prosencephalon (forebain)
• Mesencephalon (midbrain)
• Rhombencephalon (hindbrain)

Question 13

What are primary brain vesicles?

Answer 13

Fluid-filled swellings at the rostral end of the neural tube from which the brain develops

Question 14

In which primary brain vesicle is the tectum found?

Answer 14

Mesencephalon

Question 15

What are the 4 secondary brain vesicles?

Answer 15

• Telencephalon
• Diencephalon
• Metencephalon
• Myelencephalon

Question 16

In which secondary brain vesicle in the optic vesicle found?

Answer 16

The diencephalon

Question 17

What is found at the caudial end of the neural tube below the brain vesicles?

Answer 17

The spinal cord

Question 18

What is the spinal cord encased in?

Answer 18

Bony vertebrae

Question 19

What does a transverse section of the spinal cord show?

Answer 19

White and grey matter around central canal

Dorsal root, dorsal root ganglion, ventral root

Question 20

What does grey matter of the brain contain?

Answer 20

Most of the brain’s neuronal cell bodies

Question 21

What does white matter of the brain contain?

Answer 21

Lots of myelinated axons

Question 22

What gives white matter its white colour?

Answer 22

Myelin

Question 23

Which root has sensory input: dorsal or ventral?

Answer 23

Dorsal

Question 24

What does the dorsal root have which the ventral root doesn’t?

Answer 24

The dorsal root ganglion

Question 25

What does the ventral root carry?

Answer 25

Motor output

Question 26

Why do sensory neurone in the spinal cord activate multiple, contralateral interneurons?

Answer 26

So that the whole body can react

Question 27

What are spinal cord columns?

Answer 27

Set of axons that run up/down spinal cord

Question 28

Where does decussation of the spinal cord columns occur?

Answer 28

In the medulla

Question 29

What is decussation?

Answer 29

When pathways cross over onto opposite sides

Question 30

What are the meninges?

Answer 30

Membranes that line the spinal cord and brain

Question 31

Name the meninges (in order from most lateral to medial)

Answer 31

• Dura mater
• Arachnoid
• Pia mater

Question 32

The meninges are ________ with those of the brain

Answer 32

Continuous

Question 33

Which meninges has two layers?

Answer 33

Dura mater

Question 34

What are the two layers of the dura mater?

Answer 34

Endosteal and meningeal

Question 35

Which layer has the richest supply of blood vessels?

Answer 35

Dura mater: endosteal layer

Question 36

Are the endosteal and meningeal united?

Answer 36

Yes except at certain lines where they form large venous vessels called dura sinus

Question 37

What colour is cerebrospinal fluid (CSF)?

Answer 37

Straw-coloured

Question 38

Where does CSF flow?

Answer 38

• Central canal
• Brain ventricles
• Subarachnoid space

Question 39

What flows in the central canal, brain ventricles and subarachnoid space?

Answer 39

Cerebrospinal fluid

Question 40

What is CSF formed by and how does it reach the subarachnoid space?

Answer 40

Formed by the choroid plexus and gets through the medial and lateral aperture to reach the the subarachnoid space

Question 41

What does the CSF do?

Answer 41

Float and cushions the CSF

Question 42

What is the blood brain barrier and what is it formed by?

Answer 42

The blood–brain barrier (BBB) is a highly selective semipermeable membrane barrier that separates the circulating blood from the brain extracellular fluid in the central nervous system (CNS). The blood–brain barrier is formed by brain endothelial cells, which are connected by tight junctions.

Question 43

How would you retrieve important information on the state of the CNS?

Answer 43

Sample the CSF

Question 44

How would you sample CSF?

Answer 44

Lumbar puncture between 3rd and 4th lumbar vertebrae

Question 45

Why won’t the spinal cord be damaged when sampling CSF correctly?

Answer 45

Spinal cord won’t be damaged as it finishes before the end of the vertebral column

Question 46

Give an example of a disorder associated with abnormal CSF flow and what are potential consequences

Answer 46

Hydrocephaly - too much CSF

- pressure on skin, incomplete cranium, pressure built up, reduced blood flow