ANS anatomy

Question 1

the autonomic nervous system is separated how?

Answer 1

• sympathetic
• parasympathetic - vagus nerve

Question 2

Vasovagal response does what?

Answer 2

involves parasympathetic

• reduces heart rate and blood pressure etc -

Question 3

Where do the sympathetic nerves come from?

Answer 3

T1-L2

Question 4

Where do the parasympathetics come from?

Answer 4

brainstem and 4 cranial nerve

as well as the S2-S4 of the sacral part of spinal cord - supply parasympathetic in pelvis

Question 5

Parasympathetic uses what nueroreceptor?

Answer 5

acetylcholine nicotinic at pre-ganglionic

acetylcholine muscarinic at post-ganglionic

Question 6

Grey matter = what?

Answer 6

cell bodies

Question 7

What exits from the lateral horn?

Answer 7

sympathetics - go alonng the anterior root to the spinal nerve -

Question 8

sympathetic chain allows what?

Answer 8

it is the highway for sympathetic activity beyond its short origins at the cranial segments

Question 9

the pre-ganglionic fibers are myelinated or unmyelinated?

Answer 9

myelinated like most

Question 10

postganglionic sympathetic fibers are myelinated or unmylinated?

Answer 10

unmyelinated - pretty much the only unmyelinated region you’ll come across is the postganglionic sympathetic fibers which is why they are called “grey”

Question 11

do preganglionic fibers run up or down the sympathetic chain before synapsing?

Answer 11

they can run either up or down

*the postganglionic fibers may run up or down the chain before exiting*

Question 12

can preganglionic fibers leave the sympathetic chain without synapsing?

Answer 12

Absolutely!

ex) fibers can come from T5-T9 , don’t synapse and continue on as the splanchnic nerves and going to the ganglia before aortic trunk- then moves to bowels? What I’m getting here is that they can be entirely random

Question 13

the thoracic sympathetic trunk is enclosed by what?

Answer 13

the parietal pleura

Question 14

Describe the path of the thoracic sympathetic trunk

Answer 14

continuation of the cervical trunk - crosses the neck of 1st rib, heads of ribs 2-10, bodies of 11th and 12th rib - moves more medially as it moves inferiorly

Question 15

where does the vagus nerve begin?

Answer 15

tries to stay posterior and medial all the way down - (on the left side though the aorta is in the way) - runs behind the hilum of lung and tries to run on the

Question 16

What is the name of the vagus nerves in the thorax?

Answer 16

enter as vagus nerves

then makes the esophageal plexus?

exit as vagal trunks - (main contributor = right vagus nerve) anterior and (main contributor = left vagus nerve) posterior trunks

Question 17

what plexuses are contributed to by the autonomic system?

Answer 17

• cardiac plexus - in thorax
• coeliac - in abdomen
• hypogastric - in pelvis

Question 18

where do the sympathetic fibers of the cardiac plexus run to?

Answer 18

SA and AV nodes- coronary vessels and cardiac muscle

Question 19

where are the preganglionic fibers of the parasympathetic?

Answer 19

brainstem - make vagus nerve - relay to heart wall

*only synapses with the post-ganglionic fibers in the actual wall of the heart *

Question 20

What is the main function of the cardiac plexus?

Answer 20

regulate heart rate

force of each contraction

cardiac output

Question 21

divide the cardiac plexus functions into sympathetic and parasympathetic

Answer 21

Sympathetic

• increase heart rate
• increase force of contraction
• dilate coronary arteries

parasympathetic

• decrease heart rate
• reduce force of contraction
• constrict coronary arteries

Question 22

How does the brain interpret cardiac pain?

Answer 22

brain has a hard time interpreting visceral pain - so in the case of an MI when cardiac cells actually die- the visceral pain fibers travel along with the sympathetic fibers- they are co-stimulated- and therefore the level of the spinal cord that those sympathetics return to are effected ( T1-T4)

• these pain signals then enter the T1-T4 segments of the spinal cord which is the dermatome level of the left medial arm
• the phrenic nerve is also irritated in this process at (C3,4,5) which are the dermatomes to the neck - therefore you could feel it along the jaw

*cardiac pain can be variable/atypical because your body is trying to distinguish visceral feelings -

Question 23

what is the ‘typical ‘ cardiac pain?

Answer 23

crushing restrosternal pain

radiating to the neck, jaw, left arm

Question 24

What is an atypical presentation of an MI?

Answer 24

mild epigastric discomfort and severe nausea

Question 25

what are the effects of the pulmonary plexus divided into the sympathetic and parasympathetic?

Answer 25

sympathetic

• bronchodilation
• vasoconstrictuion

parasympathetic

• bronchoconstriction
• mucus secretion
• vasodilation
• cough reflex (afferent)

Question 27

what might a beta antagonist be used for?

Answer 27

it is an anti-sympathetic - they are used as an antihypertensive *but is often contraindicated in an asthmatic b/c it would cause an asthma attack*

Question 28

what is a tumour at the apex of the lung area called?

Answer 28

pancoast’s tumour - get brachial plexus symptoms etc- can put pressure on the sympathetic chain there and compromise sympathetic activity often in only one side

*horner’s syndrome*

Question 29

what is the term for pupil constriction?

Answer 29

Miosis

Question 30

What is the term for ipsilateral partial drooping of eyelid?

Answer 30

ptosis

Question 31

what is the term for sweat glands not innervated?

Answer 31

anhidrosis