Nerve
Thoracic splanchnic nerves
Visceral pathways whose fiber type depends on the named group
High-yield
The usual thoracic pattern is greater T5–T9 toward the celiac ganglia, lesser T10–T11 toward aorticorenal and related plexuses, and least T12 toward the renal plexus. Contributions and relays vary.
Overview
The greater, lesser and least thoracic splanchnic nerves carry preganglionic sympathetic fibers toward abdominal ganglia. They also carry returning visceral afferents. The name splanchnic alone does not imply sympathetic fibers: pelvic splanchnic nerves are parasympathetic.
Reference facts
- Origin
- Thoracic spinal preganglionic neurons send axons through the sympathetic chain without synapsing there
- Root value
- Commonly greater T5–T9, lesser T10–T11 and least T12; lumbar splanchnic contributions arise from upper lumbar levels
- Course
- Thoracic branches descend through the diaphragm to abdominal autonomic plexuses; lumbar branches reach those plexuses from below the diaphragm
- Motor
- Sympathetic regulation of abdominal viscera, including vascular tone, secretion and motility; adrenal medullary fibers act directly on chromaffin cells
- Sensory
- Visceral afferents return from abdominal organs alongside autonomic fibers
Clinical correlation
Some preganglionic fibers continue to adrenal medullary chromaffin cells without a conventional peripheral neuronal relay. These cells release catecholamines into blood as part of the sympathetic response.
Frequently asked questions
What are the roots of the thoracic splanchnic nerves?
Commonly greater T5–T9, lesser T10–T11 and least T12; lumbar splanchnic contributions arise from upper lumbar levels.
What muscles do the thoracic splanchnic nerves supply?
Sympathetic regulation of abdominal viscera, including vascular tone, secretion and motility; adrenal medullary fibers act directly on chromaffin cells.
What is the sensory distribution of the thoracic splanchnic nerves?
The thoracic splanchnic nerves carry sensation from the visceral afferents return from abdominal organs alongside autonomic fibers.
What is the course of the thoracic splanchnic nerves?
Thoracic branches descend through the diaphragm to abdominal autonomic plexuses; lumbar branches reach those plexuses from below the diaphragm.