Introduction to Nerve Anatomy

Question 1

What are the two major systems of the nervous system? (Not the CNS and PNS)

Answer 1

The somatic nervous system

The autonomic nervous system

Question 2

What are the two major systems of the autonomic nervous system? There’s a third, which?

Answer 2

The parasympathetic
The sympathetic
The enteric

Question 3

How does the somatic nervous system differ from the autonomic nervous system?

Answer 3

The somatic is voluntary while the autonomic is not.

Question 4

Explain the main difference between the parasympathetic and the sympathetic nervous system.

Answer 4

The parasympathetic is a rest and digest response

The sympathetic is a fight or flight response

Question 5

How does the autonomic nervous system differ to the somatic nervous system concerning the structure?

Answer 5

The autonomic nervous system has a chain of two neurones, the somatic doesn’t.

Question 6

Where is the synapse connecting the two neurones?

Answer 6

In an autonomic ganglion either sympathetic or parasympathetic.

Question 7

Where can you find the preganglionic neurone cell body?

Answer 7

In the CNS

Question 8

Where can you find the post ganglionic neurone cell body?

Answer 8

In the autonomic ganglion.

Question 9

What is the main structural difference between a preganglionic nerve cell and a postganglionic nerve cell?

Answer 9

The preganglionic nerve cell is myelinated. The postganglionic is not.

Question 10

What is the main structural difference between the sympathetic nervous system and the parasympathetic nervous system regarding wiring?

Answer 10

The sympathetic has a short preganglionic neurone and a long post ganglionic neurone
The parasympathetic has a long preganglionic neurone and a short post ganglionic neurone

Question 11

Where can you find the ganglia in the sympathetic nervous system?

Answer 11

As a chain or a ‘ladder’ around the spinal cord. Numerous ganglia found as a chain.

Question 12

Where can you find the ganglia in the parasympathetic nervous system?

Answer 12

Usually in the wall of the target structure.

Question 13

How is the spinal cord divided?

Answer 13

Into segments from C1 to the coccygeal segment inferior to the S5.

Question 14

How many segments of the spinal cord are there?

Answer 14

31

Question 15

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

Answer 15

Lateral horn in the T1 to L2 segments.

Question 16

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

Answer 16

In the brain stem and S2 to S4 segments.

Question 17

How can the sympathetic nervous system travel to the skin?

Answer 17

By a synapse at the entry level. Via the T1-L2 spinal nerves.
By ascending the chain to usually reach the head or neck. Travel along the wall of blood vessels.
By descending the chain to usually reach a lower limb. Via the L3 and below spinal nerves.

Question 18

How can the sympathetic nervous system travel to the abdominal viscera?

Answer 18

By traversing the chain then to a synapse in a pre-aortic ganglion. Postganglionic it gets to their targets along the blood vessels.

Question 19

What is the major source of parasympathetic preganglionic input to the thoracic and abdominal viscera?

Answer 19

The vagus nerve

Question 20

The head has four specialised parasympathetic ganglia. Which? Pre to post.

Answer 20

Ciliary ganglion (oculomotor nerve and eye)
Pterygopalatine ganglion (facial nerves and lacrimal gland)
Submandibular ganglion (facial nerves, submandibular glands and sublingual glands)
Otic ganglion (glossopharyngeal nerve and parotid gland)

Question 21

What kind of neurones goes through the dorsal root and dorsal horn?

Answer 21

Sensory neurones

Question 22

What kind of neurones goes through the ventral root and ventral horn?

Answer 22

Motor neurones

Question 23

Explain how the sympathetic nervous system communicates in terms of the anatomy of the spinal cord to the spinal nerve.

Answer 23

The soma of the motor neurone can be found in the lateral horn of the spinal horn. This is the sympathetic preganglionic nerve. It then leaves the spinal cord and the ventral root and enters the spinal nerve and then goes off on a ‘detour’ to the white rams communicans and enters the sympathetic ganglion. Here it changes to a post ganglionic unmyelinated nerve and exits via the grey ramps communican to reenter the spinal nerve and go off to its destination.

Question 24

Explain how the parasympathetic nervous system communicates in terms of the anatomy of the spinal cord to the spinal nerve.

Answer 24

Similar to the sympathetic but instead the parasympathetic takes a direct route in the spinal nerve and skips the sympathetic ganglion to go directly to its ganglia usually found in the wall of the designated tissue.