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

skull The skull, or cranium, is typically a bony enclosure around the brain of a vertebrate. In some fish, and amphibians, the skull is of cartilage. The skull is at the head end of the vertebrate. In the human, the skull comprises two prominent ...

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 horse anatomy, horses. In tailless primates (e.g. hum ...

. It is a major component of the

sympathetic nervous system The sympathetic nervous system (SNS or SANS, sympathetic autonomic nervous system, to differentiate it from the somatic nervous system) is one of the three divisions of the autonomic nervous system, the others being the parasympathetic nervous sy ...

Structure

The sympathetic trunk lies just lateral to the vertebral bodies for the entire length of the

vertebral column The spinal column, also known as the vertebral column, spine or backbone, is the core part of the axial skeleton in vertebrates. The vertebral column is the defining and eponymous characteristic of the vertebrate. The spinal column is a segmente ...

. It interacts with the

anterior rami The ventral ramus (: rami) (Latin for 'branch') is the anterior division of a spinal nerve. The ventral rami supply the antero-lateral parts of the trunk and the limbs. They are mainly larger than the dorsal rami. Shortly after a spinal nerve e ...

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 ...

by way of rami communicantes. 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 passage in the petrous part of the temporal bone of the skull through which the internal carotid artery and its internal carotid (nervous) plexus pass from the neck into (the middle cranial fossa of) the cranial cavity. ...

into the skull, and forms a plexus on the

internal carotid artery The internal carotid artery is an artery in the neck which supplies the anterior cerebral artery, anterior and middle cerebral artery, middle cerebral circulation. In human anatomy, the internal and external carotid artery, external carotid ari ...

; 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 The sympathetic ganglia, or paravertebral ganglia, are autonomic ganglia of the sympathetic nervous system. Ganglia are 20,000 to 30,000 Afferent nerve fiber, afferent and Efferent nerve fiber, efferent nerve cell bodies that run along on either s ...

. File:Gray530.png, The sympathetic trunk (yellow) can be seen just

lateral Lateral is a geometric term of location which may also refer to: Biology and healthcare * Lateral (anatomy), a term of location meaning "towards the side" * Lateral cricoarytenoid muscle, an intrinsic muscle of the larynx * Lateral release ( ...

to the

Relations

In the cervical region, the sympathetic trunk is situated upon the prevertebral fascia posterior to the

carotid sheath The carotid sheath is a condensation of the deep cervical fascia enveloping multiple vital neurovascular structures of the neck, including the common and internal carotid arteries, the internal jugular vein, the vagus nerve (CN X), and ansa c ...

Function

The sympathetic trunk is a fundamental part of the

, and part of the

autonomic nervous system The autonomic nervous system (ANS), sometimes called the visceral nervous system and formerly the vegetative nervous system, is a division of the nervous system that operates viscera, internal organs, smooth muscle and glands. The autonomic nervo ...

. 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.

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