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Anatomy - autonomic nervous system - intro


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Visceral efferent fibers
motor fibers, innervate involuntary (smooth) muscle, in the walls of organs and blood vessels, modified cardiac muscle, glands
Visceral afferent fibers
provide information about bodys internal environment, regulate BP and blood chemistry by altering heart rate, respiratory rate, vascular resistance, also pain
Name two divisions of autonomic system
Sympathetic (thoracolumbar) and Parasympathetic (craniosacral)
Where is the cell body of preganglionic neuron located?
Gray matter of CNS
Where do preganglionic fibers terminate
On postganglionic neuron
Where are the cell bodies of postganglionic neuron located?
Autonomic ganglia outside CNS
Where do postsynaptic fibers terminate?
On effector organ (smooth muscle, cardiac muscle, glands)
Which NT is used by sympathetic system?
NE (except sweat glands)
Which NT is used by parasympathetic system
Name two roots of spinal nerve
Ventral - efferent
Name two branches of spinal nerve
Ventral and dorsal rami, carry both motor and sensory fibers
What does dorsal ramus innervate
Synovial joints of the vertebral column, deep muscles of the back, overlying skin
What does ventral ramus innervate
Anterior and lateral regions of the trunk, upper and lower limbs
GSA fibers
General somatic afferent, transmit sensations from body to CNS - pain, touch, temp, proprioceptive info from muscles, tendons, joints.
Unilateral area of skin innervated by general sensory fibers of a single spinal nerve
Why doesnt lesion of single spinal nerve result in paralysis
General sensory fibers conveyed by adjacent spinal nerves overlap almost completely as they are distribute to skin, providing double coverage
General somatic efferent, transmit impulses to skeletal muscles
Unilateral muscle mass receiving innervation from the somatic motor fibers conveyed by single spinal nerve
General visceral afferent, transmit pain or subconscious visceral reflex sensations from hollow organs, glands and blood vessels to CNS
Name location of cell bodies of sensory fibers
Both visceral and general sensory fibers have their cell bodies in spinal ganglia or ganglia of cranial nerves
transmit impulses to involuntary muscle and glandular tissue
Lateral horns, location of preganglionic neurons of sympathetic division of ANS, located between T1-L2 segments of spinal cord
Name location of sympathetic postganglionic cell bodies
Paravertebral ganglia - form sympathetic chains on each side of vertebral column
Prevertebral ganglia - plexuses surrounding origins of abdominal aorta
How do axons of preganglionic neurons leave spinal cord
Through ventral roots and enter ventral rami of spinal nerves T1-L2, then pass to sympathetic chain through white rami communicantes (WRC)
What are 4 possible courses preganglionic fibers can take within sympathetic chain
1) ascend
2)descend and synapse there
3)synapse at same level it was
4) not synapse at all, and continue through splanchnic nerve to reach prevertebral ganglia
Which preganglionic nerves would follow first three routes
Nerves that innervate head, neck, body wall, limbs and thoracic cavity
Which pregnaglionic nerves would follow last route?
Nerves innervating viscera of abdominopelvic region
How do postganglionic fibers travel
They pass from paravertebral ganglia of sympathetic chains to adjacent ventral rami of spinal nerves through grey rami communicantes
Which spinal nerves get postganglionic fibers
All 31
Splanchnic nerve
Convey visceral efferent and aferent fibers to and from viscera of the body cavities
Name location of preganglionic parasympathetic cell bodies
S2-S4 segments of spinal cord

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