Intro to Autonomic Nervous System (Olinger)

Question 1

Typically, sympathetic stimulation is ______ (fight or flight), while parasympathetic stimulation is ______ (normal function and energy conservation)

Answer 1

catabolic, anabolic

Question 2

What is the parasympathetic distribution like compared to the sympathetic distribution?

Answer 2

• parasympathetic is limited: head, neck, trunk viscera; never in body wall or extremities
• sympathetic distributes to all vascular areas of the body

Question 3

What is the only glandular secretion not controlled by parasympathetic system?

How does the sympathetic system indirectly decrease glandular secretion?

Answer 3

• sweat glands = controlled by sympathetic system
• sympathetic system can indirectly decrease non-sweat gland glandular secretion through vasoconstriction

Question 4

What system stimulates vasoconstriction?

Answer 4

• sympathetic system (except coronary As.)

Question 5

What is the other name for the sympathetic nervous system? Why is it called that?

Answer 5

• thoracolumbar (T1-L2)
• it is called this because the pre-synaptic cells that cause innervation within sympathetic system are housed in the thoracic and upper lumbar area (in lateral horns)

Question 6

What are the two divisions of the sympathetic nervous system?

Answer 6

• visceral distribution: sympathetic innervation to visceral structures; organs of the trunk (heart, lungs, liver, gallbladder, GI tract, spleen, pancreas, kidneys, reproductive organs)
• parietal distribution: sympathetic innervation to smooth muscle of the skin/blood vessels and sweat glands

Question 7

What are the characteristics of the presynaptic fibers of the visceral sympathetic system? (4)`

Answer 7

Presynaptic fibers (short)

• cell bodies exist in the lateral horn of the spinal cord
• always travels in the anterior root
• always travels into the anterior ramus
• quickly exit anterior ramus and enter the paravertebral ganglia

Question 8

What are the 3 synaptic options within the visceral sympathetic system?

Answer 8

1. presynaptic fibers can enter the paravertebral ganglion and synapse onto a postsynaptic neuron in the same spinal level
2. presynaptic fibers can enter the paravertebral ganglion and ascend or descend to synapse on a postsynaptic neuron on a different spinal level
3. presynaptic fibers can enter the paravertebral ganglion and exit without synapsing and continue on through an abdominopelvic splanchnic nerve on their way to a postsynaptic neuron in prevertebral ganglion

Question 9

Where are the 2 different locations postsynaptic cell bodies (long) of the visceral sympathetic system can reside?

Answer 9

Paravertebral or Prevertebral Ganglia

• paravertebral: linked vertically to form sympathetic trunks on either side of the vertebral column, 3 ganglia also exist in the cervical, lumbar, and pelvic regions
• prevertebral: ganglia and corresponding plexuses surrounding the main unpaired branches of the abdominal aorta (Celiac Ganglion, Superior Mesenteric Ganglion, Aorticorenal Ganglion, Inferior Mesenteric Ganglin)

Question 10

What are the characteristics of the presynaptic fibers of the parietal sympathetic system? (4)

Answer 10

Presynaptic fibers (short)

• cell bodies exist in the lateral horn of the spinal cord
• always travels in the anterior root
• always travels into the anterior ramus
• quickly exit anterior ramus and enter the paravertebral ganglia

Question 11

What are the 3 synaptic options within the parietal sympathetic system?

Answer 11

1. trunk distribution: presynaptic fibers enter the paravertebral ganglion and synapse onto a postsynaptic neuron in the same spinal level
2. head, neck, and upper extremity distribution: presynaptic fibers enter the paravertebral ganglion at their own level then ascend to synapse on a postsynaptic neuron in the cervical sympathetic trunk
3. perineum and lower extremity distribution: presynaptic fibers enter the paravertebral ganglion at their own level then descend to synapse on a postsynaptic neuron in the abdominal and sacral sympathetic trunk

Question 12

Postsynaptic fibers (long) of parietal sympathetic system have cell bodies that exist in the ___________ ______, how do these fibers exit this area?

Answer 12

• paravertebral ganglia
• postsynaptic fibers exit paravertebral ganglion via gray rami communicantes back into the somatic nerve

Question 13

How do the postsynaptic fibers of parietal sympathetic system innervate the following:

• back:
• anterior and lateral trunk:
• head and face:
• posterior neck:
• anterior neck and upper extremity:
• buttocks:
• perineum and lower extremity:

Answer 13

• back: postsynaptic fibers follow the posterior rami of the spinal nerves to innervate the smooth muscle and sweat glands of the back
• anterior and lateral trunk: postsynaptic fibers follow the anterior rami of the spinal nerves, which for the trunk are intercostal, thoracoabdominal, and subcostal Ns., to innervate smooth muscle and sweat glands of the thoracic and abdominal body wall
• head and face: postsynaptic fibers follow carotid Ns. and enter the carotid periarterial plexus to innervate smooth muscle and sweat gland of the head and face
• posterior neck: postsynaptic fibers follow the posterior rami of the spinal nerves, such as suboccipital, greater, and least occipital nerves to innervate smooth muslce and sweat glands of the posterior neck
• anterior neck and upper extremity: postsynaptic fibers follow the 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
• buttocks: postsynaptic fibers follow the posterior rami of the spinal nerves called cluneal nerves to innervate the smooth muscle and sweat glands of the buttocks
• perineum and lower extremity: postsynaptic fibers follow the 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 14

What is another name for the parasympathetic nervous system? Why is it called that?

Answer 14

• craniosacral system
• it is also called this because the innervation comes from cranial and sacral cell bodies (CN III, VII, IX, X; S2-4)

(the sacral part is actually in the lumbar part of the vertebral column due to descrepencies in the spinal cord length and vertebral column)

Question 15

What are the characteristics of the presynaptic fibers of the parasympathetic system? Where are the nuclei housed?

Answer 15

Presynaptic fibers (long)

• nuclei are in the brain stem and sacral spinal levels
• cranial component exits as cranial nerves: Oculomotor N. (CN III), Facial N. (CN VII), Glossopharyngeal N. (CN IX), Vagus N. (CN X)
• sacral components exits spinal levels as pelvic splanchnic nerves

Question 16

Which cranial nerve does the bulk of parasympathetic innervation?

Answer 16

Vagus N.

Question 17

What are the characteristics of postsynaptic fibers of the parasympathetic system? Where are the nuclei housed?

Answer 17

Postsynaptic fibers (short)

• nuclei are in 4 specific cranial ganglia: (1) ciliary ganglion: Oculomotor N., (2) pterygopalatine ganglion: Facial N., (3) submandibular ganglion: Facial N., (4) optic ganglion: Glossopharyngeal N.

OR

• nuclei are in intrinsic parasympathetic ganglia: postsynaptic parasympathetic cell bodies located in the walls of target organs

(Olinger said not to worry about the facial ganglia right now)

Question 18

typically mixed sympathetic and parasympathetic plexuses that travel on the vasculature to carry the postsynaptic (for sympathetic division) and presynaptic (for parasympathetic division) to the target organs

Answer 18

autonomic plexuses

Question 19

What are the plexuses related to the 1) thorax, 2) abdomen, 3) pelvis?

(Olinger said these are not important right now for this class as they are not MSK related)

Answer 19

• thorax: pulmonary plexus, cardiac plexus, aortic plexus, esophageal plexus
• abdomen: celiac plexus, hepatic plexus, superior mesenteric plexus, renal plexus, intermesenteric plexus, inferior mesenteric plexus, superior hypogastric plexus
• pelvis: inferior hypogastric pelvic plexus, vesical plexus, uterovaginal plexus, prostatic plexus

Question 20

What is the difference between white and gray rami communicantes?

Answer 20

• white rami communicantes carry presynaptic sympathetic fibers from the ventral (anterior) primary rami to the sympathetic trunk and exist only between spinal cord segments T1 and L2
• gray rami communicantes carry postsynaptic sympathetic fibers from the sympathetic trunk to all spinal nerves