Textbook Question
Collateral sympathetic ganglia are involved with innervating
a. abdominal organs
b. thoracic organs
c. head
d. arrector pili
e. all of these
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14. The Autonomic Nervous System
Introduction to the Autonomic Nervous System
1:28 minutesProblem 8
Textbook Question
Describe the anatomical relationship of the white and gray rami communicantes to the spinal nerve, and indicate the kind of fibers found in each ramus type.
Verified step by step guidance1
Understand the basic structure of the spinal nerve: The spinal nerve is formed by the union of the dorsal (sensory) and ventral (motor) roots. It is part of the peripheral nervous system and connects to the sympathetic trunk via rami communicantes.
Define the rami communicantes: These are branches that connect the spinal nerve to the sympathetic trunk. They are divided into white rami communicantes and gray rami communicantes, each serving distinct functions and containing specific types of fibers.
Describe the anatomical relationship: The white rami communicantes are located closer to the spinal nerve and are present only in the thoracic and upper lumbar regions (T1-L2). They carry preganglionic sympathetic fibers from the spinal nerve to the sympathetic trunk. The gray rami communicantes are found at all levels of the spinal cord and carry postganglionic sympathetic fibers from the sympathetic trunk back to the spinal nerve.
Explain the fiber types in the white rami communicantes: The white rami contain myelinated preganglionic sympathetic fibers, which are responsible for transmitting signals from the central nervous system to the sympathetic ganglia.
Explain the fiber types in the gray rami communicantes: The gray rami contain unmyelinated postganglionic sympathetic fibers, which transmit signals from the sympathetic ganglia to the target organs or tissues.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Rami Communicantes
Rami communicantes are small nerve branches that connect the spinal nerves to the sympathetic trunk. They consist of two types: white rami communicantes, which carry preganglionic sympathetic fibers from the spinal nerve to the sympathetic ganglia, and gray rami communicantes, which carry postganglionic sympathetic fibers back to the spinal nerve for distribution to peripheral targets.
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Spinal Nerve Anatomy
Spinal nerves are mixed nerves that emerge from the spinal cord, containing both sensory (afferent) and motor (efferent) fibers. Each spinal nerve splits into a dorsal root, which carries sensory information, and a ventral root, which carries motor commands. The rami communicantes branch off from the spinal nerve, integrating autonomic functions with somatic nervous system pathways.
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Sympathetic Nervous System
The sympathetic nervous system is a component of the autonomic nervous system responsible for the 'fight or flight' response. It prepares the body for stressful situations by increasing heart rate, dilating airways, and redirecting blood flow to essential organs. The fibers in the rami communicantes play a crucial role in transmitting sympathetic signals from the spinal cord to various target organs throughout the body.
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