1.3 Development of CNS and PNS Flashcards Preview

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Flashcards in 1.3 Development of CNS and PNS Deck (32):
1

Define gyrus...

Raised bit of the fold of the cerebrum

2

Define sulcus...

Dip of the fold of part of the cerebrum

3

Which part of the cortex is in the post central sulcus?

Sensory

4

Which part of the cortex is in the pre central sulcus?

Motor

5

What is the cortex?

Thin layer of grey mater in the cerebrum

6

At which week does CNS development occur?

Week 3

7

Which part of the embryo forms the NEURAL PLATE?

It is formed by the ectoderm in the mid dorsal region.

8

What other cells do the neural crest cells form?

Parafollicular cells of thyroid
Dorsal root ganglion
Melanocytes
Odontoblasts - teeth
Adrenal medulla
Autonomic ganglia
Trocheal cartilage
Schwann cells

9

What forms the ventricles?

Neural tube lumen

10

Where does fusion of the neural tube begin?

Cervical region

11

How does the cavity of the tube remain in communication with the amniotic cavity?

Cephalic and caudal neuropores

12

Which neuropore closes first and at which day?

Cephalic - day 25
Caudal - day 27

13

Which conditions can occur if the neuropores don’t close correctly?

Cephalic - anencephaly
Caudal - spina bifida

14

What can prevent the incorrect closing of these neuropores?

Folic acid - 400micrograms

15

How can a fusion deficit be detected?

Ultrasound scan and mother's raised levels of alpha-fetoprotein

16

Explain; meningocele, myelomeningocele and spina bifida occulta

Meningocele - Protrusion of meninges through a gap in the spine
Myelomeningocele - Spinal cord and meninges protrude; spinal cord not formed properly
Spina bifida occulta - causes a cleft which is covered by the skin

17

What are the three primary brain vesicles that form by the fourth week

Prosencephalon, Mesencephalon and Rhombocephalon

18

By what week do the 5 secondary brain vesicles form?

5th week

19

Name the 5 secondary brain vesicles and what they form

Prosencephalon - Telencephalon (cortex), Diencephalon(thalamus and hypothalamus)
Mesencephalon - Midbrain
Rhombocephalon - Metencephalon(pons and cerebellum), Myelencephalon(medulla)

20

Which ventricles supply each of the 5 brain vesicles?

Telencephalon - lateral centricles
Diencephalon - third ventricle
Metencephalon - fourth ventricle

21

When does the surface of the brain fold?

15 weeks, major sulci formed by 28 weeks

22

By which week do all the neurons form?

12 weeks

23

What makes the brain grow after that time?

Synaptic connections - glial growth

24

How can you form new connections?

New ones can only be made by reorganisation

25

Why do rapidly growing cells require lots of nourishment?

Cells need to reach a certain size before dividing - G1

26

By which age would re-nourishment not restore the brain?

Age of 2

27

Define the somites; dermatome, myotome, sclerotome

Dermatome - skin
Myotome - muscles
Sclerotome - connective tissue

28

What is the grey matter organized into?

Basal lamina - ventral - motor
Alar lamina - dorsal - sensory

29

What do the lamina form in the spine?

They form the dorsal and ventral horn

30

How many pairs of cranial and spinal nerves are found in spinal nerves?

Cranial - 12
Spinal - 31

31

Which neurons in the CNS are formed from the neural tube?

Preganglionic autonomic neurons and motor

32

Which PNS neurons form the neural crest?

sensory and post ganglionic