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The sympathetic trunk is a fundamental part of the sympathetic nervous system, and part of the autonomic nervous system. It allows nerve fibres to travel to spinal nerves that are superior and inferior to the one in which they originated. Also, a number of nerves, such as most of the splanchnic nerves, arise directly from the trunks.
The sympathetic nervous system's primary process is to stimulate the body's fight or flight response. It is, however, constantly active at a basic level to maintain homeostasis. [4] The sympathetic nervous system is described as being antagonistic to the parasympathetic nervous system.
The bilaterally symmetric sympathetic chain ganglia, also called the paravertebral ganglia, are located just ventral and lateral to the spinal cord. [3] The chain extends from the upper neck down to the coccyx, forming the unpaired ganglion impar. Ganglia within this chain are either cervical, thoracic, lumbar, or sacral.
The white ramus communicans (pl.: rami communicantes) from Latin ramus (branch) and communicans (communicating) is the preganglionic sympathetic outflow nerve tract from the spinal cord. Each of the thoracic, and the first and second lumbar nerves contribute a white ramus communicans to the adjoining sympathetic ganglion , unlike the gray rami ...
The superior cervical ganglion (SCG) is the upper-most and largest [1] of the cervical sympathetic ganglia of the sympathetic trunk. [1] [2] It probably formed by the union of four sympathetic ganglia of the cervical spinal nerves C1–C4. [1] It is the only ganglion of the sympathetic nervous system that innervates the head and neck.
In the sympathetic division, neurons are mostly adrenergic (that is, epinephrine and norepinephrine function as the primary neurotransmitters). Notable exceptions to this rule include the sympathetic innervation of sweat glands and arrectores pilorum muscles where the neurotransmitter at both pre and post ganglionic synapses is acetylcholine .
Autonomic nervous system, showing splanchnic nerves in middle, and the vagus nerve as "X" in blue. The heart and organs below in list to right are regarded as viscera. The autonomic nervous system has been classically divided into the sympathetic nervous system and parasympathetic nervous system only (i.e., exclusively motor).
Schema of the sympathetic nervous system, showing the sympathetic ganglia and the parts of the body to which they connect Norepinephrine is the main neurotransmitter used by the sympathetic nervous system, which consists of about two dozen sympathetic chain ganglia located next to the spinal cord, plus a set of prevertebral ganglia located in ...