Cervical ganglia are clusters of nerve cell bodies located in the neck region of the sympathetic nervous system. They play a crucial role in transmitting signals that regulate various bodily functions, including heart rate and blood pressure. There are three main cervical ganglia: the superior cervical ganglion, middle cervical ganglion, and inferior cervical ganglion. These ganglia are involved in the autonomic control of organs in the head, neck, and upper body. They receive input from the spinal cord and send out nerve fibers to target organs, helping to manage responses to stress and maintain homeostasis in the body.