Development of Peripheral Nervous System

Question 1

The Peripheral Nervous System consist of what?

Answer 1

12 Cranial Nerves

Spinal Nerves

Ganglia

Enteric plexus - inervates gut

Sensory Receptors

Question 2

Discribe the order of Grey Matter

Answer 2

Dorsal or posterior horn is Sensory

The lateral horn is autonomics

The anterior or ventral horn is motor

Question 3

Describe the formation of the spinal cord

Where does it form?

What is the difference between Alar and Baslar plates?

Answer 3

Alar plate is for sensory neurons

Baslar plate is for motor neurons + presynaptic neurons for autonomics

They are seperated by the Sulcus limitans

Question 4

1st order sensory neurons come from where?

2nd and 3rd?

Answer 4

Embryonic Crest

Alar Plate

Question 5

Stem cells in the Neural Canal produce what cells in the Ventricular Zone?

Answer 5

Ependmyoblasts

Ependymal cells - Line the ventricals and Central Canal

Choroid plexus cells - Makes CSF

Question 6

Stem cells in the Neural Canal produce what cells in the Intermediate Zone?

Answer 6

Neurons

Astrocytes - Structural cells that regulate environment

Question 7

Stem cells in the Neural Canal produce what cells in the Marginal cells?

Answer 7

Mylenated axons (Oligodentrocytes)

Question 8

Where do Microglial cells come from in the CNS?

What do they do?

Answer 8

Monocytes

Phagocytose debris and dead cells

Question 9

Where is the end of the spinal cord found in adults vs infants?

Answer 9

L1 or L2 for adults

L2 or L3 for new borns

Question 10

What cells do neuro crest cells give rise to?

Answer 10

Spinal Ganglion and Sensory Neurons in the periphery

Schwann Cells

Question 11

How is the alar and basal plate signaled to form the spinal cord

Answer 11

By a gradient

High BMP from Roof plate on alar side activate PAX3 and PAX7 to generate its differentiation

High Shh from floor plate and notocord levels on basal side activate NXK2.2 and NKX6.1 to promote

(just dorsal there are slightly lower Shh and higher BMP, this allows for ventral motor neurons)

Question 12

Where does the development of the PNS come from

Answer 12

The neuro crest cells and the ectodermal placodes (from ectoderm)?

Question 13

Specific cells that develop from the neural tube (neuro ectoderm).

Answer 13

motor neurons - located in ventral horn

pre-ganglionic autonomic neurons - located in lateral horn

Question 14

Specific cells from neurocrest.

Answer 14

Neurons of dorsal root ganglia

Sensory ganglia of cranial nerves

Schwann Cells

Sympathetic and Parasympathetic neurons

Question 15

Decribe the classifications of motor neurons derived from the neuroectoderm.

Answer 15

GSE (general somatic efferent) - Somatic muscle - somite derived

GVE (general visceral efferent) - autonomics to smooth and cardiac muscles and glands

SVE (Brachial or Special visceral efferent) - muscles derived from pharyngeal arches

Question 16

Describe the classifications of motor neurons derived from the neurocrest.

Answer 16

• *GVA (General visceral afferent)**: sensory of visceral structures – Ectoderm
• *SSA (Special somatic afferent):** hearing, balance and sight – Endoderm

SVA (Special visceral afferent): taste and smell: chemical
senses

GSA (General somatic afferent): sensory in the skin, joint
capsule, tendon, muscle

Question 17

The parasympathetic or sympathetic nervous sytem are involved in a two cell link system. Describe this.

What is the difference?

Answer 17

Short peganglionic nerves from spinal cord which are myelinated send signals to long postganglionic nerves which are not

Sympathetic = short to long

Parasympathetic = long to short

Question 18

Sympathetics come from where?

Answer 18

The lateral horns of the spinal cord. Are found in the T1 to L2.

Question 19

Parasympathetics come from where?

Answer 19

Cranial Nerves III, XII, IX, X

Sacral 2nd to 4th (GVE)

Ganglia usually found in viscera or in the 4 cranial ganglia

Question 20

Describe whether the dorsal and ventral root are efferent or afferent

Answer 20

Dorsal = efferent

Ventral = afferent

Question 21

Motor neurons are derived from what?

Answer 21

The neural ectoderm

(often long axons)

Question 22

Sensory Neurons are derived from what?

Answer 22

The neura crest