Intro To ANS Flashcards
Where are the cell bodies of presynaptic fibers of the sympathetic NS located?
In the lateral horn of the spinal cord
Short fibers
Describe the route that presynaptic fibers of the sympathetic NS travel
Always travel in the anterior root —> into the anterior ramus —> quickly exit ramus and enter the paravertebral ganglia
What are the synaptic options for presynaptic fibers of the sympathetic visceral distribution?
- Enter the paravertebral ganglion and synapse onto a postsynaptic neuron in the same spinal level
- Enter the paravertebral ganglion then ascend or descend to synapse on a postsynaptic neuron in a different spinal level
- Enter the paravertebral ganglion and exit without synapsing and continue on through an abdominopelvic splanchnic nerve on their way to a post synaptic neuron in a prevertebral ganglion
Where do cell bodies of sympathetic visceral distribution postsynaptic fibers exist?
In the paravertebral or prevertebral ganglia
Long fibers
Describe sympathetic paravertebral ganglia of the visceral distribution?
Linked vertically to form sympathetic trunks on either idea of the vertebral column
Three ganglia also exist in the cervical, lumbar and pelvic regions
Describe prevertebral ganglia of the sympathetic visceral distribution
Ganglia and corresponding plexuses surrounding the main unpaired branches of the abdominal aorta
Describe the visceral distribution of the sympathetic NS
Innervation to visceral structures
What is the parietal distribution of the sympathetic NS?
Innervation to smooth muscle of the skin and blood vessels as well as sweat glands
Where do cell bodies of sympathetic parietal division postsynaptic fibers exist?
In the paravertebral ganglia
Describe the route by which sympathetic parietal distribution post synaptic fibers exit the paravertebral ganglion?
Exit the paravertebral ganglion via gray rami communicans back into the somatic nerve
For the sympathetic trunk distribution, presynaptic fibers enter the paravertebral ganglion and synapse onto what?
A postsynaptic neuron in the same spinal level
For the sympathetic head, neck and UE distribution, presynaptic fibers enter the paravertebral ganglion at their own level and then do what?
Ascend to synapse on a postsynaptic neuron in the cervical sympathetic trunk
For the sympathetic perineum and LE distribution, presynaptic fibers enter the paravertebral ganglion at their own level and then do what?
Descend to synapse on a postsynaptic neuron in the abdominal and sacral sympathetic trunk
Gray ramus communicans allows for travel from what?
From the paravertebral ganglion back to the spinal nerve
White ramus communicans allows for travel from what?
From the spinal nerve to the paravertebral ganglion
Describe the route of sympathetic trunk postsynaptic fibers to the back
Postsynaptic fibers follow the posterior rami of the spinal nerves to innervate the smooth muscle and sweat glands of the back
Describe the route of sympathetic trunk postsynaptic fibers to the get to the abdominal wall and lateral trunk
Postsynaptic fibers follow the anterior rami of the spinal nerves to innervate smooth muscle and sweat glands of the thoracic and abdominal body wall
Describe the route of head, neck and UE sympathetic postsynaptic fibers travel to get to the head and face
Postsynaptic fibers follow carotid nerves and enter the carotid perarterial plexus to innervate smooth muscle and sweat glands of the head and face
Describe the route of head, neck and UE sympathetic postsynaptic fibers travel to get to the posterior neck
Postsynaptic fibers follow the posterior rami of the spinal nerves (suboccipital, greater and least occ Ns) to innervate the smooth muscle and sweat glands of the posterior neck
Describe the route of head, neck and UE sympathetic postsynaptic fibers travel to get to the anterior neck and US
Postsynaptic fibers follow the anterior rami of the spinal nerves which for the anterior neck make up the cervical plexus and for the UE make up the brachial plexus to innervate smooth muscle and sweat glands of the anterior neck and UE
Describe the route of perineum and LE sympathetic postsynaptic fibers travel to get to the perineum and LE
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 LE
Describe the route of head, neck and UE sympathetic postsynaptic fibers travel to get to the buttocks
Postsynaptic fibers follow the posterior rami of the spinal cord nerves called cluneal nerves to innervate the smooth muscle and sweat glands of the buttocks
Where are the nuclei of parasympathetic presynaptic fibers found?
In the brain stem and sacral spinal nerves
Parasympathetic presynaptic fibers are what?
Long
What are the two main components of parasympathetic presynaptic fibers?
Cranial component associated with CNs (III, VII, IX and X) and a sacral component that exits spinal levels as pelvic splanchnic nerves
Describe parasympathetic postsynaptic fibers?
Usually short with ganglia/postsynaptic neurons near to in the target organ
Where are the nuclei of parasympathetic postsynaptic fibers found?
In four specific cranial ganglia or in the wall of the target group
What are intrinsic parasympathetic ganglia?
Postsynaptic parasympathetic cell bodies located in the walls of target organs
How are the autonomic plexuses responsible for the innervation of structures innervated by the ANS?
They are usually made of mixed sympathetic and parasympathetic plexuses that travel on the vasculature to carry the postsynaptic (for the sympathetic) and presynaptic (for the parasympathetic division) to the target organs
