Functional anatomy of ANS part II Flashcards
What are the four different routes that the GVE fibers can take once in the sympathetic chain?
- Body Wall and Limbs
- CERVICAL SPINAL NERVES AND LUMBAR AND SACRAL SPINAL NERVES; SYMPATHETIC SUPPLY TO THE HEAD
- Thoracic visceral structures
- Abdominal and pelvic visceral structures
What happens if the spinal nerve is distributed to body wall/limbs?
The preganglionic axon synapses with a postganglionic neuron in the sympathetic chain ganglion at that vertebral level
The postganglionic axon returns to the spinal nerve to be distributed to the territory of that spinal nerve
What happens if the route is to cervical spinal nerves and lumbar and sacral spinal nerves (sympathetic supply to head)?
so above T1 and below L2 - no interomedial cell column here
The preganglionic axon may ascend into the cervical or descend into the sacral (pelvic) extension of the sympathetic chain and synapse at a different vertebral level
The postganglionic axon travels through a gray ramus to join the spinal nerve at that level for distribution to the territory of that spinal nerve
this would be the cervical enlargement/lumbarosacral enlargements
In regions above T1 and L2, what will you NOT see?
No white rami communicantes!!
Only use a gray communicantes here
Sympathetic supply to the head is via what?
superior cervical ganglion!
Preganglionic sympathetic fibers from T1-2 synapse in the superior cervical ganglion; postganglionic fibers go onto the internal carotid and are distributed to visceral structures in the head
What is hornet’s syndrome?
disruption of sympathetic supply to the head
What are some hallmarks of horner’s syndrome? (4)
PTOSIS
Loss of innervation to the superior tarsal muscle
MIOSIS
Loss of innervation to dilator pupillae (sympathetically innervated)
ANHYDROSIS
Loss of innervation to sweat glands
VASODILATION
Loss of sympathetic tone to blood vessels
**usually only on one side - side where the lesion is
What happens if the route is to thoracic visceral structures?
**What is the level of vertebra this happens at?
The preganglionic axon synapses in the chain ganglion at that vertebral level
The postganglionic axon leaves the sympathetic chain as a splanchnic nerve (e.g. cardiac, thoracic)
This is true for the heart, lungs, esophagus, etc.
**Happens from T1 to T4!!!!
Preganglionics are committed to visceral structures in thoracic – ventral root, white ramus, sympathetic ganglion, synapse but don’t go back thorugh gray ramus but instead leave the ganglion!! – form a splanchnic or cardiac nerve
What happens if the rout is to the abdominal and pelvic visceral structures?
The preganglionic axon may leave the sympathetic chain WITHOUT synapsing
These splanchnic nerves will synapse in ganglia associated with branches of the abdominal aorta
The postganglionic axons will innervate most of the GI tract (ex. celiac ganglion or pre aortic ganglion) - use blood vessels of arteries to get to structure
The celiac ganglion receives preganlionic axons of what?
the greater splanchnic nerve
Other autonomic ganglia receive the preganglionic fibers of other abdominopelvic splanchnic nerves
A general feature of the parasympathetic nervous division is “craniosacral flow”…. what does that mean?
Craniosacral outflow:
‘Cranial’ associated with four cranial nerves which innervate the head or the thorax and most of the abdominal viscera (vagus, CN XI)
‘Sacral’ is from S2-S4 spinal levels to hindgut and pelvic viscera
Preganglionic axons synapse on postganglionic neurons in intramural ganglia of visceral targets
main nerve from cranial medulla is the…
vagus nerve - parasympathetic
Cardiac nerves originate from the vagus nerve and go to the cardiac plexus
….
The right and left vagus nerves form a plexus on the esophagus and continue through the diaphragm as the vagal trunks into the abdomen
….
parasympathetic fibers generally have a very long pre ganglionic fiber and a very short post ganglionic fiber
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