Introduction to the brain, neurone and overview of the nervous system and development & structure of the CNS

Question 1

what are the main functions of the nervous system?

Answer 1

• sensory - senses changes through sensory receptors
• motor- respond to stimuli
• integrative - analyses and stores information

Question 2

What are the 2 main cell types in the NS?

Answer 2

• neurons
• glial cells - supporting cells

Question 3

Describe the structure of a neuron

Answer 3

• cell body
• dendrities (process/ extension) that carries impulse toward cell body
• axon- carries impulse away from cell body
• some neurons are myelinated - contain myelin sheath around axon which increases velocity of impulse

Question 4

Compare and contrats** multipolar motor neurons vs pseudounipolar sensory neurons**

Answer 4

1. Multipolar motor neurons - have 2 or more dendrites, they have a** single axon** with 1 or more branches, **most common type **of neuron - all neurons controlling skeletal muscle & ANS
2. Psuedounipolar sensory neurons - short peripheral process from cell body to receptor, the cell body is in the sensory ganglia which is part of CNS

Question 5

What are the neuroglia in the CNS?

Answer 5

• oligodendroglia,
• astrocytes,
• ependymal cells,
• microglia

Question 6

what are the neuroglia in the PNS?

Answer 6

• satellite cells
• schwann cells

Question 7

What are the 3 classes of neuron?

Answer 7

1. sensory (afferent)
2. motor (efferent)
3. inter

SAME
(sensory afferent motor efferent)

Question 8

What are the main functions of the CNS?

Answer 8

• integrate and co-ordinate incoming and outgoing neural signals
• higher mental functions eg thinking & learning

Question 9

What is a ‘nucleus’ in the CNS (hint : different than in a cell)

Answer 9

a collection of nerve cell bodies in the CNS

Question 10

what is a ‘tract’ in the CNS?

Answer 10

• a bundle of nerve fibers (axons) connecting neighbouring or distant nuclei of the cerebral cortex

Question 11

What does grey matter contain in comparision to white matter?

Answer 11

• grey matter conatins nerve cell bodies (nuclei)
• white matter contains fibre tract systems

Question 12

What kind of shape is grey matter in the spinal cord & what are the 2 ends of it called?

Answer 12

• grey matter in the spinal cord is H shaped
• it has horns - a dorsal (posterior) horn and a ventral (anterior )horn

Question 13

What are** commissural fibres** ( type of white matter fibre)?

Answer 13

• these fibres connect the right and left hemispheres
  EGCORPUS CALLOSUM

Question 14

what are** projection fibres **(type of white matter fibres)?

Answer 14

• they connect higher and lower parts of the CNS eg corona radiata

Question 15

what are** association fibres** (type of white matter fibre)?

Answer 15

• they connect structures **within the same hemisphere **
• eg arcuate short fibres

Question 16

what 2 structures is the CNS protected by?

Answer 16

Bone - ie skull and vertebral column
Membranous coverings - the meninges which has 3 layers

Question 17

what are the** 3 layers of the meninges**?

Answer 17

• pia matter (delicate - innermost layer)
• arachnoid mater (spider web like)
• dura mater (dense, collagenous)

Question 18

what fluid sits between pia mater and arachnoid matter?

Answer 18

cerebrospinal fluid

Question 19

what is the leptomeninx?

Answer 19

the arachnoid and pia mater make up the leptomeninx
* they are called this because of their cellular structure

Question 20

what are the 2 layers of the dura mater?

Answer 20

• inner **meningeal **layer
• outer periosteal layer

Question 21

what does the inner layer of the dura mater form?

Answer 21

the inner meningeal layer forms many infoldings
1. falx cerebri in the longitudinal cerebral fissure which seperates the 2 hemipsheres of the brain
2. also the tentorium cerebelli - seperates occipital lobes of hemispheres from the cerebellum
3. **falx cerebelli **
4. **diaphragma sellae **- smallest infolding - covers pituitary gland

Question 22

how are the** venous sinuses ** formed by dura mater?

Answer 22

by separating the 2 layers of dura mater along lines which creates the sinuses

Question 23

what is the function of the venous sinuses?

Answer 23

• large veins from brain surface empty blood into these sinuses
• the sinuses drain into the internal jugular veins (IJV)

Question 24

Describe the arachnoid mater

Answer 24

• web like arachnoid trabeculae bridge
• not attached to dura but** pressure of the CSF keeps it in direct contact**
• arachnod granuations project through dura into blood - filled venous sinus

Question 25

Describe pia mater

Answer 25

• the pia mater gives the brain a** shiny appearance**
• it** adheres to the brain surface **and follows all contours

Question 26

what is the CSF secreted by?

Answer 26

the choroid plexus in the ventricles

Question 27

what are the properties of CSF?

Answer 27

• clear liquid
• surrounds brain & spinal cord to provide cushioning and nourishment
• similar contents to plasma - however less protein and different ion conc

Question 28

Where does CSF go to from choroid plexus?

Answer 28

• leaves ventricles and enters the sub arachnoid space
• it then exits the subarachnoid space via arachnoid granulations to venous blood in dural venous sinuses

Question 29

what are the ventricles of the brain?

Answer 29

• lateral ventricle
• 3rd ventricle (dincephalon)
• 4th ventricle

Question 30

what structure connects the 3rd ventricle to the 4th ventricle?

Answer 30

the cerebral aqueduct

Question 31

what is the** diencephalon**?

Answer 31

a division of the forebrain

Question 32

what is meningitis?

Answer 32

inflammation of the meninges - either bacterial or viral

Question 33

how many cervical vertebrae versus cervical nerves are there?

Answer 33

• 7 cervical vertebrae
• 8 cervical nerves

Question 34

what is a dermatome?

Answer 34

area of skin supplied by a single spinal nerve root eg L4

Question 35

what is a myotome?

Answer 35

region of skeletal muscle supplied by single spinal nerve root eg L3

Question 36

Describe sensory ganglia vs automatic ganglia & give examples of each

Answer 36

• sensory ganglia - ganglia without synapse eg dorsal roots ganglion
  -automatic ganglia - ganglia w/ synapses eg otic ganglion

Question 37

describe ipsilateral vs contralateral

Answer 37

ipsilateral - on the same side
contralateral - on the opposite side

Question 38

what does decussate mean in relation to the nervous system?

Answer 38

to switch from one side to the other