Sympathetic Nuclei
The sympathetic nuclei are clusters of neuronal cell bodies located in the central nervous system, specifically within the intermediolateral cell column (IML) of the spinal cord.
Location
- Found in the lateral horn of the spinal cord gray matter
- Present from T1 to L2/L3 spinal cord segments
- Also referred to as the thoracolumbar outflow
Function
- Contain preganglionic sympathetic neurons
- Axons exit via ventral roots, then enter the sympathetic chain ganglia (paravertebral) or prevertebral ganglia
- Postganglionic neurons project to target organs:
- Heart (↑ rate and contractility)
- Pupils (dilation)
- Skin (sweating, vasoconstriction)
- Gastrointestinal tract (↓ motility)
Organization
Region | Spinal Levels | Role |
---|---|---|
Intermediolateral Nucleus | T1–L2 | Origin of preganglionic sympathetic neurons |
Paravertebral Ganglia | Along vertebral column | Relay to postganglionic neurons |
Prevertebral Ganglia | Abdomen (e.g., celiac, mesenteric) | Control of abdominal viscera |
Clinical Relevance
- Horner Syndrome: Damage to the sympathetic pathway causes ptosis, miosis, and anhidrosis
- Spinal cord injuries above T1 can interrupt sympathetic output
- Autonomic dysreflexia in spinal lesions above T6