Nerve tracts from the head and neck converge in the superior cervical ganglion or superior cervical ganglion. Anatomically, four broad areas can be distinguished, each comprising several branches; these rami belong to different nerve tracts and form part of the sympathetic nervous system. Damage to the cervical supercervical ganglion can result in loss of body function.
What is the cervical superior ganglion?
The cervical superior ganglion is located between the longus capitis muscle and the digastric muscle. The structure at the level of the second cervical vertebra represents a collection of neuronal cell bodies; these centers form important switching points in the peripheral nervous system and correspond to the basal ganglia or nuclei in the brain. Neuronal cell bodies (somata) lie close together here and form connections with each other with their nerve fibers and dendrites. In the cervical ganglion, sympathetic information from the head and neck unite, which is why the cervical ganglion belongs to the border cord (truncus sympathicus). This also includes two other cervical ganglia as well as 20 or 21 other nerve cell body assemblies. In total, the cervical supercervical ganglion measures 2.5 cm.
Anatomy and structure
The cervical superior ganglion consists of four areas that can be roughly distinguished without having a clear anatomic barrier. Each of these areas groups together several branches, which physiology attributes to different nerves. The anterior branches or rami anteriores form a connection to the cephalic ganglia. The nerve fibers responsible for this branch further and finally reach the eyes; in addition, they innervate the salivary glands in another branch. The rami anteriores of the superior cervical ganglion include nerve fibers from the nervis carotici interni and the nervi carotici externi. They terminate at the carotid artery, with the rami anteriores winding separately around the inner and outer branches of the blood vessel. These braids around the carotid artery are called the internal carotid plexus or the external carotid plexus, depending on their location – translated roughly as “braid of the internal carotid artery” or “of the external carotid artery,” respectively. The rami mediales form the middle region of the ganglion cervicale superius. They transmit nerve signals to/from the heart, larynx, and pharynx. In addition, the superior and middle cervical ganglions (cervicale medium ganglion) are connected via the rami inferiores. In contrast, the rami laterales, i.e., the lateral branches from the superior cervical ganglion, lead to the spinal cord and to various cranial and other nerves.
Function and Tasks
The main function of the cervical supercervical ganglion is to interconnect the nerves from the neck and head that converge here. Those fibers belong to the sympathetic nervous system, which is a subdivision of the autonomic nervous system. In general, it is considered an activating functional unit. Among other things, it controls skeletal muscle, cardiac activity, blood pressure, and overall metabolism. The carotid nerves run from the carotid plexus first to the cephalic ganglia and on to the eye and salivary gland. Neuronal signals from the nerve fibers trigger the secretion of digestive fluid in the salivary gland. In medicine, the organ is also known as the glandula salivatoria and thus refers to the entirety of the salivary glands. Three major and five minor salivary glands produce secretions for the oral cavity. The jugular nerve also passes through the cervical ganglion. The rami mediales not only include sympathetic supply to the larynx and pharynx, but also contribute to cardiac function. The superior cardiac nerve, also known as the superior cardiac nerve, is responsible for this task. In addition to it, two other cardiac nerves exist: cardiacus cervicalis medius and inferior nerves. Sympathetic activation speeds up the heartbeat and causes vascular pressure to increase. This may be a response to physical exertion, stress or anxiety, for example. In this way, the heart is able to pump more blood and thereby ensure the supply of blood to the body under stressful conditions.
Diseases
The cervical superior ganglion and its circuitry belong to the autonomic nervous system. Functions such as heartbeat and blood pressure were long considered to be beyond its control; however, recent studies now show that patients with elevated blood pressure can lower it voluntarily with sufficient exercise.The training consists of biofeeedback, which visually illustrates blood pressure and thus enables sufferers to influence it. Patients who are successful at this may not be able to directly target specific muscles, glands or nerves, but complex mechanisms allow them to influence it indirectly. However, this experimental biofeedback approach is still in the early stages of research and not every patient succeeds in achieving an effect. Ancient meditation and trance techniques from Asia may have their origins in similar biological mechanisms. In addition to general diseases and nerve damage, two specific clinical pictures can manifest in connection with the ganglion cervicale superius. Horner syndrome manifests as constricted pupil (miosis), drooping eyelid (ptosis), and apparent drooping of the eyeball (enophthalmos). Not only lesions at the supercervical ganglion can cause Horner’s syndrome; nerve damage in other areas of the sympathetic system may also be a cause. Familial dysautonomia (Riley-Day syndrome), on the other hand, is a genetic disease that results in the loss of nerve cells. If the cervical superior ganglion is affected, lacrimation may be absent, blood pressure may fluctuate widely, and digestion may be impaired. Other potential symptoms include limitations in temperature sensation, gait and speech problems, and short stature and spinal curvature.