Lecture 20: Autonomics

Question 1

Why is the sympathetic division considered thoracolumar?

Answer 1

Presynpatic cell bodies are from the lateral horn of the thoracic part of the spinal cord (and upper lumbar)

Question 2

How does the sympathetic presynpatic fiber find its way to the paravertebral ganglion?

What is this fiber called?

Answer 2

Travels though the Anterior Root and Anterior Ramus to enter the paravertebral ganglion

Known as White Ramus Communicans

Question 3

In the sympathetic divison, pre-synaptic fibers are _____ while post-synpatic fibers _____.

Answer 3

In the sympathetic divison, pre-synaptic fibers are short and myelinated while post-synpatic fibers long and unmyelinated.

Question 4

There are three ways a sympathetic presynaptic fiber can synapse and reach its visceral target. In simple terms, what are the three options?

Answer 4

Option 1: Presynaptic Fibers enter Paravertebral Ganglion and synapse onto a Postsynaptic Neuron in the same spinal level

Example: Sympathetic innervation to heart

Option 2: Presynaptic Fibers enter Paravertebral Ganglion and ascend or descend to synapse on a Postsynaptic Neuron a different spinal level

Example: Sympathetic innervation to heart from cervical area

Option 3: Presynaptic Fibers enter Paravertebral Ganglion and exit without synapsing and continue on through an Abdominopelvic Splanchnic Nerve on their way to a Postsynaptic Neuron in Prevertebral Ganglion

Example: Sympathetic innervation to GI System

Question 5

Are splanchnic nerves pre-sympathetic or post-sympathetic?

Answer 5

BOTH: Splanchinc nerves innervate organs and have left the prevertebral ganglia!

Option 1 and 2: Synapse occurs in paravertebral ganglia and the post-synaptic fiber is considered to be a splanchinc nerve.

Option 3: Synapse occurs in prevertebral ganglia and the pre-synaptic fiber going to this ganglai is considered to be a splanchinc nerve.

Question 6

What are the four prevertebral ganglia?

Hint: All related to GI

Answer 6

Celiac Ganglion

Superior Mesenteric Ganglion

Aorticorenal Ganglion

Inferior Mesenteric Ganglion

I don’t think its important to memorize these - just be aware these exist

Question 7

There are three ways a sympathetic presynaptic fiber can synapse and reach its parietal target. In simple terms, what are the three options?

Answer 7

Option 1: Presynaptic Fibers enter Paravertebral Ganglion and synapse onto a Postsynaptic Neuron in the same spinal level

Example: Innervating intercostal nerves

Option 2: Presynaptic Fibers enter Paravertebral Ganglion ascend or descend to synapse on a Postsynaptic Neuron a different spinal level

Example: Innervating sweat glands in cheek

Option 3: Presynaptic Fibers enter Paravertebral Ganglion and exit without synapsing and continue on through an Abdominopelvic Splanchnic Nerve on their way to a Postsynaptic Neuron in Prevertebral Ganglion

Example: Innervating GI tissue

Question 8

How does the sympathetic parietal pathway different from visceral?

Answer 8

Instead of becoming a splanchinic nerve, the post-sympathetic fiber exits via a gray rami communicans and travels through anterior and posterior rami

Question 9

Describe the trunk dristribution in the back

Answer 9

Postsynaptic Fibers follow the Posterior Rami of the Spinal Nerves to innervate the smooth muscle and sweat glands of the Back

Question 10

Describe the trunk distribution in the anterior and lateral trunk.

Answer 10

Postsynaptic Fibers follow Anterior Rami of the Spinal Nerves

(Intercostal, Thoracoabdominal and Subcostal Ns.) to innervate smooth muscle and sweat glands of the Thoracic and abdominal body wall

Question 11

Describe the head, neck, UE distribution of the head and face.

Answer 11

Postsynaptic Fibers follow Carotid Ns and enter the Carotid Periarterial Plexus to innervate smooth muscle and sweat gland of the Head and Face

Question 12

Describe the head, neck, UE distribution of the posterior neck.

Answer 12

Postsynaptic Fibers follow Posterior Rami of the Spinal Nerves Suboccipital, Greater and Least Occipital nerves) to innervate the smooth muscle and sweat glands of the Posterior Neck

Question 13

Describe the head, neck, UE distribution of the anterior neck and UE.

Answer 13

Postsynaptic Fibers follow Anterior Rami of the Spinal Nerves, which for the Anterior Neck make up the Cervical Plexus of Nerves and for the Upper Extremity make up the Brachial Plexus of Nerves to innervate the smooth muscle and sweat glands of the Anterior Neck and Upper Extremity

Question 14

Describe the Perineum and Lower Extremity Distribution of the Buttocks.

Answer 14

Postsynaptic Fibers follow the Posterior Rami of the Spinal Nerves called Cluneal nerves to innervate the smooth muscle and sweat glands of the Buttocks

Question 15

Describe the Perineum and Lower Extremity Distribution.

Answer 15

Postsynaptic Fibers follow Anterior Rami of Spinal Nerves which make up the Lumbar and Sacral Plexuses to innervate smooth muscle and sweat glands of the Perineum and Lower Extremity

Question 16

Why is the parasympathetic divison called “Craniosacral?”

What are the nerves that exist this area called?

Answer 16

Pre-sympathetic neurons found in brainstem and sacral spinal levels

• Cranial Nerves 3, 7, 9, 10
• Pelvic Splanchnic Nerves

Question 17

Where can you find the four parasympathetic ganglion and what cranial nerves run through them?

Answer 17

Ciliary Ganglion: fibers from CN 3 (Oculomotor Nerve)

Pterygopalatine Ganglion: fibers from CN 7: Facial Nerve)

Submandibular Ganglion: fibers from CN 7 (Facial Nerve)

Otic Ganglion: Fibers from CN 9: (Glossopharyngeal Nerve)

Question 18

In the parasympathetic divison, pre-synaptic fibers are _____ while post-synpatic fibers _____.

Answer 18

In the sympathetic divison, pre-synaptic fibers are long/myelinated while post-synpatic fibers short/unmyelinated.

Post-synaptic cell bodies normally found in target organs