Sympathetic ganglia

Sympathetic Ganglia

The sympathetic ganglia are a collection of nerve cell bodies (ganglia) situated in the sympathetic nervous system, a part of the autonomic nervous system. These ganglia are critical in the body's fight or flight response, regulating involuntary bodily functions such as heart rate, digestion, respiratory rate, pupillary response, urination, and sexual arousal. The sympathetic ganglia are divided into two major chains: the paravertebral ganglia (or sympathetic chain ganglia) and the prevertebral ganglia.

Structure

The sympathetic ganglia are organized into two main groups: the paravertebral ganglia and the prevertebral ganglia.

Paravertebral Ganglia

The paravertebral ganglia form a chain that runs alongside the vertebral column. This chain extends from the base of the skull to the coccyx, forming the sympathetic trunk. The paravertebral ganglia are connected to the spinal nerves through the rami communicantes, which contain both myelinated and unmyelinated fibers. These ganglia are primarily involved in the distribution of the sympathetic innervation to the body wall, head, neck, limbs, and thoracic cavity.

Prevertebral Ganglia

Prevertebral ganglia are located anterior to the vertebral column and close to the major abdominal arteries. They include the celiac, superior mesenteric, and inferior mesenteric ganglia. These ganglia primarily provide sympathetic innervation to the abdominal and pelvic viscera.

Function

The sympathetic ganglia play a crucial role in the autonomic nervous system, preparing the body for physical activity by increasing heart rate, dilating bronchial passages, decreasing motility of the large intestine, constricting blood vessels, and causing pupil dilation. These actions are part of the body's fight or flight response to stress.

Clinical Significance

Abnormalities or damage to the sympathetic ganglia can lead to various disorders, including Horner's syndrome, which is characterized by ptosis (drooping eyelid), miosis (constricted pupil), and anhidrosis (lack of sweating) on the affected side of the face. Another condition, complex regional pain syndrome (CRPS), involves severe chronic pain that can occur in an arm or leg after injury, surgery, stroke, or heart attack and is thought to be caused by dysfunctional sympathetic ganglia.

See Also

• Autonomic nervous system
• Parasympathetic nervous system
• Neuron
• Fight or flight response

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