The cervical sympathetic chain is a part of the autonomic nervous system located in the neck region. It consists of a series of interconnected nerve fibers that run alongside the cervical vertebrae. This chain plays a crucial role in regulating various involuntary functions, such as heart rate, blood pressure, and sweating. The cervical sympathetic chain is divided into three main ganglia: the superior cervical ganglion, the middle cervical ganglion, and the inferior cervical ganglion. These ganglia communicate with other parts of the body, influencing the function of organs and tissues in the head, neck, and upper body.