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44 Cards in this Set

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Nucleus vs. Ganglions
1. Nucleus is a collection of nerve cell bodies within the CNS
2. Ganglions are collections of nerve cell bodies inside the PNS
How many types of ganglia are there?
1. Dorsal root ganglia (sensory+ NO synapse)
2. Autonomic ganglia (visceral motor + HAVE synapse)
What areas does the dorsal primary ramus supply?
1. Intrinsic muscles of the back
2. Skin of the back
Note: DPR is divided into 2 branches.
What areas does the ventral ramus supply? (Compare size to dorsal ramus)
1. Distributes to all other areas of the body
2. Much larger in size than dorsal ramus
REVIEW: Name parts of typical spinal "slice" and spinal nerve.
1. Ventral horn
2. Dorsal horn
3. Gray matter
4. Ventral (anterior) root
5. Dorsal root
6. Vertebral body
7. DRG (spinal ganglion)
8. Dorsal primary ramus
9. Ventral primary ramus
10. Sympathetic Chain Ganglion
11. Spinal Nerves
12. Sensory nerve fibers
13. Somatic motor fibers
How does sympathetic chain connect to spinal nerves?
Via white & gray rami communicantes.
(White IN & Gray OUT)
How long are spinal nerves before split?
What do spinal nerves divide into?
1. Very short (almost immediate divide)
2. Dorsal ramus & ventral ramus
Where are sensory fiber nerves located?
Dorsal root ganglion (DRG)
NOTE: There are NO synapses here
Pseudounipolar process???
Divides into a central process & a peripheral process
(e.g. Dorsal primary ramus)???
Somatic motor fibers:
1. Origin
2. Path
3. Destination
1. Arise from anterior horn cells
2. Pass into ventral root, becomes spinal nerve, passes into either dorsal/ventral ramus (Remember = Rami are MIXED)
3. Skeletal muscle (voluntary)
Sympathetic ganglion
1. Where are cell bodies located?
2. Path
1. Cell bodies of sympathetic nerve cells are located in lateral horn
2. Axons exit via ventral root and form part of spinal nerve; All sympathetic fibers pass into sympathetic chain ganglion where synapse (on occasion) occurs immediately & axons exit through rami.
Motor aspect of nervous system is divided into 2 parts.
1. Somatic Nervous system
2. Autonomic Nervous system
Somatic Nervous system:
1. Target organs
2. # neurons involved
3. Origin of neuron
4. Path
1. Skeletal muscles
2. Single neuron
3. Anterior horn cells of spinal cord
4. Axons exit ventral horn, out ventral root, form part of spinal nerve, then out via dorsal/ventral ramus
Autonomic Nervous system:
1. Definition
2. Target organs
1. Part of nervous system which contributes to the unconcious maintenance of homeostasis by its actions on target organs below.
2. Cardiac muscle, Smooth muscle & glands
2 Environments can elicit involuntary responses. Give examples.
1. External: hot weather causes you to sweat. (involuntary response)
2. Internal: If stomach secretes too much acid, involuntary reflex is set up to reduce acid.
What type of system is the ANS defined as?
What travels along with it, but is not part of the ANS?
1. Efferent (visceromotor) system
2. Afferent (sensory) system = travel alongside efferent nerve fibers, carrying impulses from target organs
Functionally ANS divided into 2 parts:
1. Sympathetic = 'fight or flight'
2. Parasympathetic = 'rest & repose'
These divisions have OPPOSITE effects
Somatic Nervous System Flow Diagram
1, Somatic (Voluntary)
2. Motor
3. Skeletal Muscle
Autonomic Nervous System Flow Diagram
Sympathetic
1. Autonomic
2. Sympathetic
3. Motor
4. Glands, cardiac & smooth muscle
Autonomic Nervous System Flow Diagram
Parasympathetic
1. Autonomic
2. Parasympathetic
3. Motor
4. Glands, cardiac & smooth muscle
Parasympathetic Fibers:
1. Target Organs
2. # Neurons involved
3. Origin of neuron
1. Glands, cardiac & smooth muscle
2. 2 neurons involved (hence synapse)
3. First neuron is in CNS
Where does parasympathetic nervous system arise?
Arises on either side (PARA) of the origin of the sympathetic system. Specifically, S2-S4 & Brainstem
Parasympathetic Axons:
1. Origin
2. Distribution
3. Location of synapse
1. Only leave CNS from Cranial nerves C3, C7, C9, C10 or Sacral nerves S2, S3, S4 = CRANIOSACRAL OUTFLOW
2. Extend only to internal organs or viscera (hollow cavities)
3. Synapse in ganglia found either in or near the organ supplied.
BIG picture summary: Parasympathetics
1. Tends to Target...
2. Distribution stays where?
3. Distributed by what nerves?
4. Location of 2nd order neurons.
'Rest & Repose'
1. Targets glands, smooth & cardiac muscle, but usually nonvascular smooth muscle (e.g. SM in guts/tubes)
2. Distribution stays in cavities
3. Cranial nerves 3,7,9,10 & Sacral nerves 2,3,4
4. Near or in the organ of the structure supplied
Sympathetic Nervous System:
1. Target Organs
2. # Neurons involved
3. Origin of neuron
1. Glands, cardiac & smooth muscle
2. 2 Neurons
3. CNS
Where does sympathetic nervous system arise?
Arises from the intermedial lateral cell column of spinal cord segments T1-L2
Sympathetic Axons:
1. Origin
2. Path
3. Distribution
4. Location of synapse
1. Only leave CNS btwn T1-L2
THORACOLUMBAR OUTFLOW
2. From lateral horn, preganglionic axons pass into ventral root, leads to spinal nerve & connects to sympathetic trunk & ganglia via white rami communicantes; fibers synapse after reach trunk, then postganglionic fibers proceed to target organs
3. Periphery, body walls, & limbs
4. Paravertebral ganglia (Sympathetic chain) or prevertebral ganglia
BIG picture summary: Sympathetics
1. Tends to target...
2. What must all fibers enter?
3. Where does chain distribute?
1. Periphery/body wall, limbs, & even dermatomes
2. Sympathetic chain ganglion
3. Body wall, limbs, cavities
How do sympathetic fibers get to body wall/ limbs? (OPTION 1)

What happens in periphery?
1. Leave via T1-L2 of spinal cord, synapse immediately in sympathetic chain, then use post-ganglionic connection to spinal nerve (called gray ramus communicantes), then out to periphery
2. Constrict blood vessels, supply glands
How do sympathetic fibers get to body wall/ limbs? (OPTION 2)
1. Leave T1-L2 spinal cord segmentsm run up or down sympathetic chain, synapse elsewhere in chain at other level of entry, & then follow gray ramus communicantes to spinal nerve found at different level of entry.
Fundamentals:
1. # pairs of spinal nerves
2. Where does smooth muscle exist?
3. Where do glands exist?
1. 31 pairs of spinal nerves
2. Exists in every blood vessel inferior to the cranial fossae & at base of every hair follicle in body (pili erector-hair stand)
3. Everywhere on the body surface (Generally true)
Where do sympathetic fibers reach?
Reach every square inch of the body surface by communicating with and 'hitching' a ride with every spinal nerve.
Note: Spinal nerves distribute to every square inch of the body.
Describe path through sympathetic chain (part that is same for all levels of spine).
Cell body lies in lateral horn where axon comes out, forms a component of the ventral root, enters the spinal nerve, & enters the sympathetic chain like EVERY pre-synaptic sympathetic fiber.
How do sympathetic fibers reach levels T1-L2?
Synapse occurs immediately in sympathetic chain, axons from post-ganglionic second order neuron at this level proceeds back to spinal nerve via gray ramus communicantes. The axon then extends out to these structures (target organs) in the vental body wall.
How do sympathetic fibers reach levels above T1?
Pre-ganglionic fibers arise & the axon enters the sympathetic trunk via a white ramus communicantes. Pre-synaptic fiber (no synapse at this level) must ascent to get to higher level, then synapse, & post-synaptic fiber enters spinal nerve via gray ramus communicantes & distributes post-synaptic fibers to spinal nerves above T1.
How do sympathetic fibers reach levels below L2?
Pre-synaptic sympathetic fibers ALL arise from spinal cord segments T1-L2. Axons enter sympathetic trunk at that level. In order to reach nerves below this level, they descend in the sympathetic trunk, a synapse occurs, & then post-ganglionic fibers would follow gray ramus communicantes to spinal nerve at this level, & axon goes out to target organs at this level (hip or lower limb). (BELOW L2)
Sympathetic Options: Visceral
These fibers do NOT use spinal nerves or gray ramus communicantes--They go to the periphery.
1. Leave CNS, synapse in chain, & go immediately to target organ
2. Leave CNS, do NOT synapse in chain, pass throught diaphragm, go to preaortic (prevertebral) ganglion, synapse in ganglion, & then go to target organ (thoracic or abdominopelvic)
What does splachnic mean?
Visceral
Sympathetic Innervation of Thoracic Viscera
1. PATH
Cell body lies in spinal cord. Axon passes out through ventral root, enters the spinal nerve, passes into sympathetic trunk via WRC. Synapse occurs. Post-ganglionic fiber extends to heart & lungs
CARDIOPULMONARY SPLANCHNIC NERVES
Sympathetic Innervation of Abdominopelvic Viscera
1. PATH
Pre-synaptic cell bodies leave thoracic portions of spinal cord, pass into sympathetic chain WITHOUT synapsing, go through prevertebral ganglion where they would synapse & post-ganglionic fibers would extend to abdominopelvic organs via a throcic splanchnic nerve called ABDOMINOPELVIC SPLANCHNIC NERVE
Ventral & Dorsal Rami to dermatomes T1-L2
Sympathetic pathways to the visceral and initially to the body wall & limbs.
1. Axon passes into sympathetic trunk, synapse occurs, postganglionic fibers run to spinal nerve & supply smooth muscle & glands at levels of T1-L2 via dorsal or ventral rami.
While ANS is primarily described as efferent (motor=visceromotor) system, what travels alongside?
Afferent (sensory) fibers travel alongside efferent nerve fibers, carrying impulses from target organs (similar to that found in somatic system)
Physiological Feedback with Parasympathetics:
What type of fibers run with this system?
1. Visceral afferent fibers that run with parasympathetics are REFLEX fibers (e.g. blood pressure, not enough oxygen etc.) Sensation is initiated & passes influence to initiate reflex arc.
Physiological Feedback with Sympathetics:
What type of fibers run with this system?
Pain fibers in the thoracic region run w/ sympathetics. Pain afferents run w/ cardiac nerves & reach the sympathetic trunk & axon passes via WHITE rami communicantes & follows spinal nerve, The cell bodies for all afferent fibers lie in the dorsal root ganglion. Cell bodies central processes would carry this visceral afferent pain fiber into the spinal cord rather than brain @ this point (why?).