The sympathetic trunks (sympathetic chain, gangliated cord) are a paired bundle of nerve fibers that run from the base of the

skull The skull is a bone protective cavity for the brain. The skull is composed of four types of bone i.e., cranial bones, facial bones, ear ossicles and hyoid bone. However two parts are more prominent: the cranium and the mandible. In humans, th ...

to the

coccyx The coccyx ( : coccyges or coccyxes), commonly referred to as the tailbone, is the final segment of the vertebral column in all apes, and analogous structures in certain other mammals such as horses. In tailless primates (e.g. humans and othe ...

. They are a major component of the

sympathetic nervous system The sympathetic nervous system (SNS) is one of the three divisions of the autonomic nervous system, the others being the parasympathetic nervous system and the enteric nervous system. The enteric nervous system is sometimes considered part of t ...

Structure

The sympathetic trunk lies just lateral to the

vertebral bodies The spinal column, a defining synapomorphy shared by nearly all vertebrates,Hagfish are believed to have secondarily lost their spinal column is a moderately flexible series of vertebrae (singular vertebra), each constituting a characteristic i ...

for the entire length of the

vertebral column The vertebral column, also known as the backbone or spine, is part of the axial skeleton. The vertebral column is the defining characteristic of a vertebrate in which the notochord (a flexible rod of uniform composition) found in all chordate ...

. It interacts with the anterior rami of

spinal nerves A spinal nerve is a mixed nerve, which carries motor, sensory, and autonomic signals between the spinal cord and the body. In the human body there are 31 pairs of spinal nerves, one on each side of the vertebral column. These are grouped into the ...

by way of

rami communicantes Ramus communicans (plural rami communicantes) is the Latin term used for a nerve which connects two other nerves, and can be translated as "communicating branch". Structure When used without further definition, it almost always refers to a commu ...

. The sympathetic trunk permits preganglionic fibers of the

to ascend to spinal levels superior to T1 and descend to spinal levels inferior to L2/3.Greenstein B., Greenstein A. (2002): Color atlas of neuroscience – Neuroanatomy and neurophysiology. Thieme, Stuttgart – New York, . The superior end of it is continued upward through the

carotid canal The carotid canal is a passageway in the temporal bone of the skull through which the internal carotid artery enters the middle cranial fossa from the neck. Structure The carotid canal is located within the middle cranial fossa, at the petrous ...

into the skull, and forms a

plexus In neuroanatomy, a plexus (from the Latin term for "braid") is a branching network of vessels or nerves. The vessels may be blood vessels (veins, capillaries) or lymphatic vessels. The nerves are typically axons outside the central nervous system ...

on the

internal carotid artery The internal carotid artery (Latin: arteria carotis interna) is an artery in the neck which supplies the anterior circulation of the brain. In human anatomy, the internal and external carotids arise from the common carotid arteries, where these ...

; the inferior part travels in front of the

, where it converges with the other trunk at a structure known as the ganglion impar. Along the length of the sympathetic trunk are sympathetic ganglia known as paravertebral ganglia. File:Gray530.png, The sympathetic trunk (yellow) can be seen just

lateral Lateral is a geometric term of location which may refer to: Healthcare *Lateral (anatomy), an anatomical direction * Lateral cricoarytenoid muscle * Lateral release (surgery), a surgical procedure on the side of a kneecap Phonetics *Lateral co ...

to the

Function

The sympathetic trunk is a fundamental part of the

, and part of the

autonomic nervous system The autonomic nervous system (ANS), formerly referred to as the vegetative nervous system, is a division of the peripheral nervous system that supplies internal organs, smooth muscle and glands. The autonomic nervous system is a control system t ...

. 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 The splanchnic nerves are paired visceral nerves (nerves that contribute to the innervation of the internal organs), carrying fibers of the autonomic nervous system ( visceral efferent fibers) as well as sensory fibers from the organs ( visceral a ...

, arise directly from the trunks.

Additional images

File:Spinal nerve.svg, The formation of the spinal nerve from the dorsal and ventral roots. File:Gray829.png, Dissection of side wall of pelvis showing sacral and pudendal plexuses. File:Gray837.png, Sacral plexus of the right side. File:Gray839.png, Diagram of efferent sympathetic nervous system. File:Gray840.png, Sympathetic connections of the ciliary and superior cervical ganglia. File:Sacral sympathetic.jpg, Sacral sympathetic

References

External links

* - "The position of the right and left vagus nerves, and sympathetic trunks in the mediastinum." * - "The Female Pelvis: The Posterolateral Pelvic Wall" * - "Autonomic Connections of the Spinal Cord"
Diagram at umm.edu
{{Authority control Sympathetic nervous system

Structure

Function

Additional images

See also

References

External links