Thoracic splanchnic nerves
Thoracic splanchnic nerves are 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...

 that arise from the sympathetic trunk
Sympathetic trunk
The sympathetic trunks are a paired bundle of nerve fibers that run from the base of the skull to the coccyx.-Structure:...

 in the thorax
The thorax is a division of an animal's body that lies between the head and the abdomen.-In tetrapods:...

 and travel inferiorly to provide sympathetic innervation to the abdomen
In vertebrates such as mammals the abdomen constitutes the part of the body between the thorax and pelvis. The region enclosed by the abdomen is termed the abdominal cavity...

. The nerves contain preganglionic sympathetic and visceral efferent fibers.

There are three main thoracic splanchnic nerves:
Name Ganglia Description
| greater
T5-T9 or T5-T10 diaphragm
Thoracic diaphragm
In the anatomy of mammals, the thoracic diaphragm, or simply the diaphragm , is a sheet of internal skeletal muscle that extends across the bottom of the rib cage. The diaphragm separates the thoracic cavity from the abdominal cavity and performs an important function in respiration...

 and enters the abdominal cavity, where its fibers synapse at the celiac ganglia
Celiac ganglia
The celiac ganglia or coeliac ganglia are two large irregularly shaped masses of nerve tissue in the upper abdomen. Part of the sympathetic subdivision of the autonomic nervous system , the two celiac ganglia are the largest ganglia in the ANS, and they innervate most of the digestive tract.They...

. The nerve contributes to the celiac plexus
Celiac plexus
The celiac plexus or coeliac plexus, also known as the solar plexus, is a complex network of nerves located in the abdomen, where the celiac trunk, superior mesenteric artery, and renal arteries branch from the abdominal aorta...

, a network of nerves located in the vicinity of where the celiac trunk branches from the abdominal aorta
Abdominal aorta
The abdominal aorta is the largest artery in the abdominal cavity. As part of the aorta, it is a direct continuation of the descending aorta .-Path:...

. The fibers in this nerve modulate the activity of the enteric nervous system
Enteric nervous system
The enteric nervous system is a subdivision of the autonomic nervous system that directly controls the gastrointestinal system in vertebrates.It is derived from neural crest.-Function:...

 of the foregut
The foregut is the anterior part of the alimentary canal, from the mouth to the duodenum at the entrance of the bile duct. At this point it is continuous with the midgut...

. They also provide the sympathetic innervation to the adrenal medulla
Adrenal medulla
The adrenal medulla is part of the adrenal gland. It is located at the center of the gland, being surrounded by the adrenal cortex. It is the innermost part of the adrenal gland, consisting of cells that secrete epinephrine , norepinephrine , and a small amount of dopamine in response to...

, stimulating catecholamine
Catecholamines are molecules that have a catechol nucleus consisting of benzene with two hydroxyl side groups and a side-chain amine. They include dopamine, as well as the "fight-or-flight" hormones adrenaline and noradrenaline released by the adrenal medulla of the adrenal glands in response to...

| lesser
T9-T12, T9-T10, T10-T12, or T10-T11 aorticorenal ganglion
Aorticorenal ganglion
Sympathetic input to the gut comes from the sympathetic chain next to the thoracic vertebrae. The upper nerve supply leaves the sympathetic chain by the greater splanchnic nerve and synapses in the celiac ganglion before proceeding onto the foregut...

. The nerve modulates the activity of the enteric nervous system of the midgut
The midgut is the portion of the embryo from which most of the intestines develop. After it bends around the superior mesenteric artery, it is called the "midgut loop"...

| least or lowest
T12-L2, or T11-T12 The nerve travels into the abdomen, where its fibers synapse
In the nervous system, a synapse is a structure that permits a neuron to pass an electrical or chemical signal to another cell...

 in the renal ganglia.

The nerve's origins can be remembered by the "4-3-2 rule", accounting for the number of ganglia giving rise to each nerve. However, different sources define the nerves in different ways, so this rule may not always be reliable.

Additional images

External links

- "The position of the right and left vagus nerves, and sympathetic trunks in the mediastinum." - "Posterior Abdominal Wall: The Celiac Plexus"
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