Sympathetic trunk

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Nerve: Sympathetic trunk
Abdominal portion of the sympathetic trunk, with the celiac plexus and hypogastric plexus. (Sympathetic trunk labeled at center left.)
Scheme showing structure of a typical spinal nerve. 1. Somatic efferent. 2. Somatic afferent. 3,4,5. Sympathetic efferent. 6,7. Sympathetic afferent.
Latin	truncus sympathicus
Gray's	subject #214 976
Innervates
From
To
MeSH	[1]

The sympathetic trunk (sympathetic chain, gangliated cord) is a bundle of nerve fibers that runs from the base of the skull to the coccyx. There are two sympathetic trunks in the body, a right one and a left one.

Structure

Trunk

The sympathetic trunk travels inferiorly from the skull, just lateral to the vertebral bodies. It interacts with the spinal nerves or their ventral root by way of rami communicantes.

The superior end of it is continued upward through the carotid canal into the skull, and forms a plexus on the internal carotid artery; the inferior part travels in front of the coccyx, where it converges with the other trunk at a structure known as the ganglion impar.

Paravertebral ganglia

Along the length of the sympathetic trunk are ganglia known as paravertebral ganglia (ganglia trunci sympathici). The ganglia are distinguished as cervical, thoracic, lumbar, and sacral and, except in the neck, they closely correspond in number to the vertebrae.

They are arranged thus:

Cervical portion: 3 ganglia

The cervical portion usually has three ganglia: superior, middle, and inferior cervical ganglia. The inferior ganglion may be fused with the first thoracic ganglion to form a single structure, the stellate ganglion.

Nerves emerging from cervical sympathetic ganglia contribute to the cardiac plexus, among other things.

Thoracic portion: 12 ganglia

The thoracic portion typically has 12 ganglia. Emerging from the ganglia are thoracic splancic nerves (the greater, lesser, and least splanchic nerves) that help provide sympathetic innervation to abdominal structures.

Also, the ganglia of the thoracic sympathetic trunk have both white and gray rami communicantes. The white rami carry sympathetic fibers arising in the spinal cord into the sympathetic trunk.

Lumbar portion: 4 ganglia

The lumbar portion typically has 4 ganglia. The lumbar splanchnic nerves arise from the ganglia here, and contribute sympathetic efferent fibers to the nearby plexuses.

The first two lumbar ganglia have both white and gray rami communicantes.

Sacral portion: 4 or 5 ganglia

As the sympathetic trunk heads inferiorly down the sacram, it turns medially. There are generally four or five ganglia. In addition to gray rami communicantes, the ganglia send off sacral splanchnic nerves to join the inferior hypogastric plexus.

Near the coccyx, the right and left sympathetic trunks join to form the ganglion impar.

Function

The sympathetic trunk is a fundamental part of the sympathetic division of the autonomic nervous system. It allows nerve fibers to travel to spinal nerves that are superior and inferior to the one in which it originated. Also, a number of nerves, such as most of the splanchnic nerves, arise directly from the trunks.

Additional images

The formation of the spinal nerve from the dorsal and ventral roots.

Transverse section of thorax, showing relations of pulmonary artery.

Dissection of side wall of pelvis showing sacral and pudendal plexuses.

Sacral plexus of the right side.

See also

• Autonomic nervous system
• Splanchnic nerves
• Spinal nerves
• Sympathetic nervous system
• Sympathectomy

External links

• SUNY Figs 21:04-04 - "The position of the right and left vagus nerves, and sympathetic trunks in the mediastinum."
• SUNY Labs 43:15-0102 - "The Female Pelvis: The Posterolateral Pelvic Wall"
• GPnotebook -1764753348
• Dictionary at eMedicine Sympathetic+trunk
• Dictionary at eMedicine ganglion+of+sympathetic+trunk
• Atlas of anatomy at UMich n3a6p1 - "Autonomic Connections of the Spinal Cord"
• Diagram at umm.edu

This article was originally based on an entry from a public domain edition of Gray's Anatomy. As such, some of the information contained herein may be outdated. Please edit the article if this is the case, and feel free to remove this notice when it is no longer relevant.

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