19 - Organisation of nervous system

Question 1

How is the nervous system broken down?

Answer 1

- Enteric (autonomic): Nervous system within the wall of the gut

- CNS: Processing

Question 2

What are the main differences between the sympathetic and parasympathetic nervous system?

Answer 2

Sympathetic has chain

Question 3

What is the difference between the somatic and autonomic nervous system?

Answer 3

Somatic is voluntary and uses one motor neurone

Autonomic is involuntary and uses two neurones between CNS and target organ

Question 4

What is a ganglion?

Answer 4

A collection of cell bodies in the PNS

Question 5

What is the spinal nerve?

Answer 5

When the dorsal and ventral root coalesce

Question 6

What is the difference betweent the dorsal and ventral root?

Answer 6

Dorsal is purely sensory

Ventral is purely motor

Question 7

Draw the cross section through a spinal cord.

Answer 7

Question 8

How many spinal cord segments are there?

Answer 8

30-32, therefore there are 30-32 pairs of spinal nerve pairs

Question 9

How do the dorsal and ventral roots plug into the spinal cord?

Answer 9

• Multiple times, has rootlets

Question 10

What is a dermatome?

Answer 10

An area of skin supplies by a single spinal nerve

Question 11

What is the monosynaptic reflex arc?

Answer 11

Question 12

What are sensory and motor neurones?

Answer 12

Sensory - carry impulses towards CNS

Motor - carry impulses away from the CNS

Question 13

Why can’t we normally see myelin?

Answer 13

Xyulene and toluene strip the lipid away, can only see with staining with metals

Question 14

Where are the cell bodies of sensory neurones?

Answer 14

In the dorsal root of spinal nerves either in spinal or cerebral (head nerve) ganglia

Question 15

Where is the synapse between the two motor neurones in the autonomic system?

Answer 15

• Autonomic ganglion (sympathetic)
• Ganglion near organs (parasympathetic)

Question 16

Where are the cell bodies of the pre and post gaglionic neurones found?

Answer 16

Pre - CNS

Post - Autonomic ganglion (sympathetic), Walls of organs (parasympathetic)

Question 17

What is the difference between the pre and post ganglionic neurones?

Answer 17

• Pre myelinated
• Post unmyelinated
• Cell bodies in different areas

Question 18

What is the sympathetic chain?

Answer 18

Chain on the left and right of the spinal chord containing post-ganglion cell bodies

Question 19

Where does the post ganglionic neurone sit in the parasympathetic nervous system?

Answer 19

• Close to or in the wall of an organ

Question 20

Where are autonomic preganglionic neurone cell bodies found in the CNS?

Answer 20

- Parasympathetic: Brain stem (head and neck) and S2-S4 regions

- Sympathetic: From lateral horn in T1-L2

Question 21

What is the lateral horn?

Answer 21

Found from T1-L2

Contain sympathetic pre-ganglionic neurones

Question 22

Draw a picture to show where the pre-synaptic ganglion comes from in sympathetic and parasympathetic.

Answer 22

S - LHS

PS - RHS

Question 23

In the sympathetic nervous system how does an electrical signal get from the CNS to the effector?

Answer 23

Pre ganglionic originates in LH, travels down VH, through VR as motory and into sympathetic ganglion where it meets post ganglionic.

Signal goes back into spinal nerve through grey ramus branch as unmyelinated

Question 24

In the parasympathetic nervous system how do the electrical signals get from the CNS to the effector?

Answer 24

• Originate in same area of sacral chord
• Travel through VH, VR, spina nerve, to ganglion near organs
• This is because pre-ganglionic are longer in parasympathetic

Question 25

How does the sympathetic nervous system get to the head and neck if only spans T1-T2?

Answer 25

- Ascend the sympathetic chain and then synapse

Question 26

In the sympathetic nervous system what three routes can post-ganglionic neurones take to get to the skin?

Answer 26

**- Synapse at level of entry** (T1-L2) (post-ganglionics get to targets via spinal nerve) **- Ascend the chain and then synapse** (post-ganglionics get to targets via walls of blood vessels, supplies head and neck) **- Desend the chain and synapse** (post ganglions get to targets via spinal nerve below L3)

Question 27

In the sympathetic nervous system what ways can pre-ganglionics take to get to the gut?

Answer 27

- Traverse the chain, dont synapse in it, go to pre-aortic ganglion where they synapse - Ganglia sat in aortic blood vessels supplying the gut - Post ganglions get to target via blood vessels

Question 28

What are splachnic nerves?

Answer 28

Nerves that arise from the sympathetic chain and supply the gut with sympathetic pre-ganglionic supply

Question 29

Apart from pre-ganglions and post ganglions, what else line sympathetics destined for the gut?

Answer 29

- Sensory fibres that relay pain from viscera back to CNS

Question 30

What are the ganglia called that supply the viscera and the penis?

Answer 30

- Not named

Question 31

What are the ganglia called that supply the head?

Answer 31

Parasympathetic **- Ciliary ganglion:** pre from oculomotor nerve and post to eye pupil **- Pterygopalatine ganglion:** pre from facial nerve and post to lacrimal gland - **Submandibular ganglion:** pre from facial nerve and post to submandibular and sublingual salivary glands **- Otic ganglion:** pre from glossopharyngeal nerve and post to parotid gland

Question 32

What are the cranial nerves?

Answer 32

Nerves that come from the brain stem. Pre-ganglionic nerves go through this nerve

Question 33

How does the CNS feel pain from the abdomen?

Answer 33

Sensory fibres travel along sympathetics destined for the abdomen so they can relay pain back to the CNS