1 - Autonomic Nervous System

Question 1

What is different regarding neural connections in the somatic vs autonomic nervous system?

Answer 1

Somatic = One neuron connection to muscle

Autonomic = Two neuron pwathway connects effection (preganglionic and postganglionic)

Question 2

Two Types of Autonomic Neurons:

1. Preganglionic
2. Post Ganglionic

Answer 2

Preganglionic:

• First, cell body in CNS, axon passes out of CNS to synapse with dendrites/cell bodies of secondary neuron in PNS, myelinated (appears white) axon

Postganglionic:

• Cell body in autonomic ganglion, has axon travel to structure, unmyelinated (appears grey) axon

Question 3

What are the three types of autonomic ganglia?

What are they based on?

Answer 3

Based on location in body

1. Sympathetic Chain
2. Prevertebral Ganglia
3. Terminal Ganglia

Question 4

Sympathetic Chain Ganglia

Answer 4

Located in sympathetic trunk, located adjacent to vertebral column

Extends form vertebra C1 to coccyx

Question 5

Prevertebral (or preaortic) Ganglia

Answer 5

Located anterior to the lumbar vertebrae as well as abdominal aorta; most associated with the branches of abdominal aorta (celiac, superior and inferior mesenteric arteries)

Question 6

Terminal Ganglia

Answer 6

Located within the wall of an organ or adjacent to the organ, parasympathetics

Question 7

Sympathetics:

Preganglionic Neuronal Cell Body Location

Post Ganglionic Neuronal Cell Body Location

Function

Answer 7

Pre: Lateral horns of grey matter of spinal cord at thoracic and upper lumbar levels (T1-T12, L1-L3); Thoraco-Lumbar

Post: Located in sympathetic chain ganglia and preaortic (prevertebral)

Functions: Fight or Flight: Increase HR, dilate voluntary vessels/restrict skin/gut, EPINEPHRINE

Question 8

Parasympathetics:

Preganglionic Cell Bodies

Post Ganglionic Cell Bodies

Functions

Answer 8

Pre - Cranial Nerve Nuclei 3, 7, 9, 10; gray matter of Sacra S2-S4; Cranio Sacral

Post - Located in terminal ganglia

Functions - Rest and Digest, Can cause opposite from sympathetics, exerts over short, limited region of body

Question 9

Do organs usually receive sympathetics or parasympathetics?

Answer 9

Both para/symp fibers usually supply the same organ or structure

Usually act antagonistically

Question 10

What three regions only receive supply from sympathetics?

Answer 10

1. Sweat Glands
2. Medulla of Adrenal Gland
3. Arrector Pili Muscles (good pimples, erect hair)

Question 11

Cranial Components of Parasympathetics:

Preganglionic Cell Bodies

Preganglionic Axons

Terminal Ganglia (Post Gang Bodies)

Postganglionic Axon

Answer 11

PreG Cell Bodies - Nucleus of Vagus Nerve (CN 10) in brainstem

Pre GAxons - Travel with vagus nerve descend neck; hitch ride with other structures (arteries, broncus, etc.)

Terminal Ganglia - Close / in Wall of targets

PostG Axon - Axon of neuron in terminal ganglion, short

Question 12

What organs are targets for the Cranial Component of Parasympathetic Division?

What is their embryological origin?

Answer 12

1. All thoracic Viscera
2. Most of gut (as far as left colic flexure of large intestine)
   - - -

Foregut / Midgut

Question 13

Sacral Components of Parasympathetics:

Preganglionic Cell Bodies

Preganglionic Axons

Terminal Ganglia (Post Gang Bodies)

Postganglionic Axon

Answer 13

PreG Bodies - Gray matter of S2 - S4

PreG Axons - Leave spinal cord in ventral root, enter ventral ramus of S2 - S4; Ventral Rami of Sacral Spinal nerves enter Pelvic Cavity, form Pelvic Splanchnic Nerves, plexus on Arteries

Terminal Ganglia - Close to or in walls of targets

PostG Axon - Short

Question 14

What organs are targets for the Sacral Comonent of Parasympathetics Division?

What is the embryological origin of these structures?

Answer 14

1. Distal part of large bowel (beyond left colic flexure)
2. Urinary Bladder
   - - -

Hindgut

Question 15

Sympathetics:

Preganglionic Cell Bodies

Preganglionic Fibers (Axons)

Exit and Rally?

Answer 15

PreG Bodies - Lateral horn T1-T12, L1-L3

Axons - Myelinated, exit the spinal cord via the ventral roots of spinal nerves and enter ventral rami of T1-T12, L1-L3

**Exit and Rally: Exit via White Ramus Communicans, rally to Sympathetics Chain Ganglion within Sympathetic Trunk

Question 16

Sympathetics Trunk Location

Contents

Answer 16

Located lateral to vertebral column from C1 - Coccyx

Contains Preganglionic Sympathetic Fibers and Sympathetic Chain Ganglia located along its length

Question 17

Sympathetics: Synapse with Chain Ganglia

Three Target Destinations

Answer 17

1 .Synapse with postganglioni neuronal cell body at same level

2. Pass through chain ganglia (no synapse) and travel up or down sympathetic trunk to do #1 at a different level
3. Cervical/Upper Thoracic Sympathetic Chain Ganglia can synapse and leave three cervical chain ganglia and upper thoracic sympathetic chain ganglia to go directly to structures in head, neck, thorax without entering a spinal nerve

Question 18

What route does the postganglionic sympathetic neuron travel following synapse?

What does this junction join?

Answer 18

Gray Ramus Communicans

*Postganglionic axons are unmyelinated, hence gray name

Joins ventral ramus of a spinal nerve to travel to cutaneous structures or exits dorsal rami of spinal nerve to innervation structures of back

Question 19

Sympathetics: Synapse with Pre-Aortic (Prevertebral) Ganglion

Where are ganglia located around?

Answer 19

Pass through chain ganglia (no synapse) and form Splanchnic Nerves (4x)

Emerge from from levels T5 - L2 to join Preaortic Ganglia in abdomen and pelvis

Located around roots of major aortic branches

Question 20

Sympathetics: Synapse with Pre-Aortic (Prevertebral) Ganglion

Postganglionic Fibers

Answer 20

Fibers leave Preaortic Ganglion following synapse; and form Perivascular Plexus on branches of Aorta

Distributed to Abdominal-Pelvic Viscera

Question 21

Memory Aid to Differentiate Splanchnic Nerves

Answer 21

Pelvic Splanchnic Nerves are

Parasympathetics,

Splanchnic Nerves are

Sympathetics

Question 22

Which division of the ANS are pain afferents associated with?

Where are your cell bodies?

Answer 22

Sympathetics

Cell bodies of sensory neurons located in dorsal root ganglia of Spinal nerves T1 - T12, L1-L3

Question 23

Where do the peripheral processes of sensory neurons (pain) leave the spinal nerve?

Where do they enter?

Answer 23

Ventral rami via White Rami Communicans

Enter sympathetic trunk

Question 24

Contents of Splanchnic Nerves

Answer 24

1. Preganglionic Sympathetic Fibers to Preaortic Ganglia
2. Visceral Sensory Fibers from Organ Innervated

Question 25

Contents of Periarterial Plexus

Answer 25

1. Post ganglionic Sympathetic Fibers
2. Preganglionic Parasympathetic Fibers (e.g. vagus)
3. Visceral Sensory Fibers from Abdomino/pelvic organ