Sympathetic trunk
Encyclopedia
The sympathetic trunks (sympathetic chain, gangliated cord) are a paired bundle of nerve fibers that run from the base of the skull
to the coccyx
.
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
.
Along the length of the sympathetic trunk are ganglia known as paravertebral ganglia
.
. It allows nerve fibers 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.
Human skull
The human skull is a bony structure, skeleton, that is in the human head and which supports the structures of the face and forms a cavity for the brain.In humans, the adult skull is normally made up of 22 bones...
to the coccyx
Coccyx
The coccyx , commonly referred to as the tailbone, is the final segment of the vertebral column. Comprising three to five separate or fused vertebrae below the sacrum, it is attached to the sacrum by a fibrocartilaginous joint, the sacrococcygeal symphysis, which permits limited movement between...
.
Structure
The sympathetic trunk travels in a downward direction from the skull, just lateral to the vertebral bodies. It interacts with the spinal nerves or their ventral rami by way of rami communicantes.The superior end of it is continued upward through the carotid canal
Carotid canal
On the interior surface of the temporal bone, behind the rough surface of the apex, is the large circular aperture of the carotid canal, which ascends at first vertically, and then, making a bend, runs horizontally forward and medialward.-Contents:...
into the skull, and forms a plexus
Plexus
A plexus is a part of nervous system. Plexus has a slightly different definition in vertebrates and in invertebrates.- In vertebrates :In vertebrates, a plexus is an area where nerves branch and rejoin. The electrical signals do not mix; rather, the fibres travel together with their electrical...
on the internal carotid artery
Internal carotid artery
In human anatomy, the internal carotid arteries are two major arteries, one on each side of the head and neck. They arise from the common carotid arteries where these bifurcate into the internal and external carotid artery, and they supply the brain....
; the inferior part travels in front of the coccyx
Coccyx
The coccyx , commonly referred to as the tailbone, is the final segment of the vertebral column. Comprising three to five separate or fused vertebrae below the sacrum, it is attached to the sacrum by a fibrocartilaginous joint, the sacrococcygeal symphysis, which permits limited movement between...
, where it converges with the other trunk at a structure known as the ganglion impar
Ganglion impar
The pelvic portion of each sympathetic trunk is situated in front of the sacrum, medial to the anterior sacral foramina. It consists of four or five small sacral ganglia, connected together by interganglionic cords, and continuous above with the abdominal portion...
.
Along the length of the sympathetic trunk are ganglia known as paravertebral ganglia
Paravertebral ganglia
Along the length of the sympathetic trunk are ganglia known as ganglia of sympathetic trunk or paravertebral ganglia. The ganglia are distinguished as cervical, thoracic, lumbar, and sacral and, except in the neck, they closely correspond in number to the vertebrae.-Arrangement:Only the cervical...
.
Function
The sympathetic trunk is a fundamental part of the sympathetic division of the autonomic nervous systemAutonomic nervous system
The autonomic nervous system is the part of the peripheral nervous system that acts as a control system functioning largely below the level of consciousness, and controls visceral functions. The ANS affects heart rate, digestion, respiration rate, salivation, perspiration, diameter of the pupils,...
. It allows nerve fibers 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
Splanchnic nerves
The splanchnic nerves are paired nerves that contribute to the innervation of the viscera, carrying fibers of the autonomic nervous system as well as sensory fibers from the organs...
, arise directly from the trunks.
