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What is the narrowest definition of the ANS?
The part of the PNS that is motor to smooth muscle, cardiac muscle, glands
What else can be added?
Control by CNS for higher center, sensory components that provide feedback
body wall and extremities (bones, joints, skeletal muscles, skin)
internal organs, glands, bloods, vessels
4 basic functional fiber types but 2 in ANS.
ANS—Visceral efferent and visceral afferent
2 division of ANS= ?
- 1. Sympathetic
- 2. Parasympathetic
Why is sympathetic division called thoracolumbar part of the ANS?
Preganglionic cell bodies are found in the lateral intermediate gray column from spinal cord segments from T1-L2
Parasympathetic= cranciosacral. why?
Preganglionic nerves found in brain stem and from S2-S4
Differences in Para vs Sym? Anatomically
- Para—synapse the target organ, long preganglionic, short post ganglionic
- Sym-- Synapse near the CNS, short preganglionic, post ganglionic
Functional differences of parasympathetic and sympathetic?
- Para— Rest and Digest. Protective, vegetative, secretomotor
- Sym—Fight or Flight. Fear, strength, endurance, vasoconstriction
DIfferences of PARA and SYM Pharmacologically...
- Para— ACh
Preganglionic sympathetic axons in rge spinal cord to the paravertebral ganglia of the sympathetic trunk. Motor goes from the gray matter to the ventral root, to the sympathetic trunk.
- 1. Terminal at synapse of sympathetic trunk at level of entry
- 2. Ascend in the sym trunk to a higher level and then synapse
- 3. Descend in the sympathetic Trunk to a lower level and then synapse
- 4. Leave the sym trunk in a splanchnic nerve (still preganglionic fibers) and a synapse in a collateral ganglion.
- Vertebra, muscle, great vessels can synapse elsewhere
Sympathetic fibers leaving the trunk
- 1. Postganglionic fibers leave the sym at all levels via gray communicating rami to ravel in spinal nerves in the limbs and body walls
- 2. Post gang fibers called Direct Visceral Branches leave the sympathetic trunk and go directly to thoracic viscera
- 3. Preganglion fibers leave the sym trunk in splanchnic Nerves and then synapse in the collateral ganglia in the abdomen and pelvis and synapase there onto a post ganglionic fiber
- 4. Postganglionic fibers leave the sym trunk and travel on carotoid arteries (periarterial plexus) to supple viscera in the head
Which spinal nerves have white communicating rami and why?
- ONLY T1-L2
- Pregangllionic sympathetics leave the spinal cord only at three levels to enter the sympathetic trunk
Which spinal nerves have gray communicating rami and why?
- All spinal nerves, postganglionic sym leave the sym trunk at all levels to enter all spinal nerves
- Therefore only T1 through L2 spinal nerves have both white and Gray communication rami
- NO trunk of the ganglia—most are located in the target organ itself
- Origin—Brain stem nuclei of CN 3,7,9,10 and lateral intermediate gray column of spinal cord segments S2-S4
What general areas do the cranial parasympathetics supply?
- Cranial Nerves 3,7,9 suppply viseral of the head
- CN 10 supplies viscera of thorax and part of abdomen