PNS Development

Question 1

Which systems does the PNS include?

Answer 1

1. Autonomic /(Visceral)
2. Somatic
3. Enteric nervous sytem

Question 2

How is the PNS involved in the Somatic nervous system?

Answer 2

Via sensory neurons to the CNS and from CNS to voluntary muscles.
(Voluntary muscles are striated and skeletal)

Question 3

Where do we find ganglions, in the somatic or autonomous system?

Answer 3

In the autonomous.

Question 4

Is “ALS” a disease of the CNS or PNS?

Answer 4

ALS is the dying of motor neurons, so CNS

Question 5

How many pairs of spinal nerves and ganglia do we have?

Answer 5

31 pairs.

Question 6

How are the spinal nerve pairs divided?

Answer 6

8 cervical spinal nerve pairs
12 thoracic spinal nerve pairs
5 lumbar spinal nerve pairs
5 sacral spinal nerve pairs
1 coccygeal nerve pairs

Question 7

Which fibres does the spinal nerves (mixed nerve) contain off?

Answer 7

1. Autonomic fibres
   - Motor output to (1) body wall, (2) thoracic cavity, (3) limbs and (4) head/neck
2. Motor fibres
   - Ventral part of the spinal cord & Neurons which grow out to the muscles via the ventral root
3. Sensory fibres
   - Peripheral nerves run via the dorsal root ganglia

Question 8

Where do you expect to find “association neurons” and what are their function?

Answer 8

CNS
Its the bridge between sensory and motor output

Question 9

Where do the spinal nerves start?

Answer 9

Where the ventral and dorsal tracts merch

Question 10

We find ganglions in the Autonomous nervous system (so, it is a 2-step-process). Where is it adjacent to?

Answer 10

Sympathetic ganglion is close to the CNS.
Parasympathetic is close to the organs.

Question 11

Which autonomic system is craniosacral?

Answer 11

Parasympathetic Nervous System

Question 12

Which autonomic system is thoracolumbar?

Answer 12

Sympathetic Nervous System

Question 13

What are the neurotransmitters used by the somatic-, sympathetic- and parasympathetic nervous system?

Answer 13

1. Somatic: Acetylcholine
2. Sympathetic: Pre-ganglion: Acetylcholine, Post-ganglion: Norepinephrine/ Epinephrin
3. Parasympathetic: Acetylcholine

Question 14

What is the fibre-origin of sympathetic- and parasympathetic nerves?

Answer 14

Sympathetic nerves: Thoracic & Part lumbar
Parasympathetic nerves: Cranial & Sacral

Question 15

What happens to the neural crest cells during neurolation?

Answer 15

They become sensory ganglion

Question 16

What happens at week 5 at the beginning of PNS development?

Answer 16

Step. 1
- Sympathetic ganglia form
- Neural migration from neural crest cells

Question 17

What happens in week 6 to PNS development?

Answer 17

Step. 2
- Somatic motor neurons bundle together to form ventral root
- Migrate cranio-caudal direction

Question 18

What happens at Step. 3 of PNS development?

Answer 18

Step. 3
- Somatic, autonomous and sensory fibres bundle together
- they connect with association neurons

Question 19

What happens at Step. 4 in week 6.5 of PNS development?

Answer 19

Step 4.
- Development of the “sympathetic chain ganglia”