Superior cervical ganglion

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Superior cervical ganglion 1

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Sympathetic Trunk and SCG innervation

Superior cervical ganglion is a neuronal structure located at the top of the sympathetic trunk in the neck. It is the largest of the cervical ganglia, serving as a key relay point in the sympathetic nervous system, which is part of the autonomic nervous system. The autonomic nervous system regulates involuntary body functions, including heart rate, digestion, and respiratory rate.

Anatomy

The superior cervical ganglion is located near the base of the skull, anterior to the transverse processes of the cervical vertebrae C1-C4. It typically measures about 2.5 cm in length. This ganglion sends out nerve fibers that innervate various structures in the head and neck, including the pupils (pupillary dilation), the glands (such as the salivary glands and sweat glands), and blood vessels (vasoconstriction).

Function

The superior cervical ganglion plays a crucial role in the sympathetic outflow to the head and neck. It is involved in several autonomic functions:

• Vasomotor control: Regulates the diameter of blood vessels in the head and neck, affecting blood pressure and blood flow.
• Pupillary dilation: Controls the dilation of the pupils in response to low light or sympathetic stimulation.
• Sweating: Controls sweating in the head and neck region.
• Salivation: Influences the rate and composition of saliva produced by the salivary glands.

Clinical Significance

Disorders or injuries affecting the superior cervical ganglion can lead to a range of symptoms, including:

• Horner's syndrome: A condition characterized by ptosis (drooping eyelid), miosis (constricted pupil), anhidrosis (lack of sweating), and enophthalmos (sunken eyeball), typically on one side of the face. It can result from damage to the ganglion or its postganglionic fibers.
• Cluster headaches: Some theories suggest that dysfunction in the superior cervical ganglion may contribute to the pathophysiology of cluster headaches, a type of severe, recurrent headache.

See Also

• Autonomic nervous system
• Sympathetic nervous system
• Cervical ganglia
• Horner's syndrome
• Cluster headaches