Cardiac Plexus: Structure, Function & Diseases

The cardiac plexus is a nerve plexus of the autonomic nervous system, also known as the cardiac plexus. The deep portions of this network consist of sympathetic as well as parasympathetic nerve fibers and control the automatic action of the heart, which is beyond any external influence. Damage to the plexus can result in palpitations, heart palpitations, or other cardiac discomfort.

What is the cardiac plexus?

Networks or interweavings of conduit pathways such as veins, lymphatics, arteries, or nerve pathways are what anatomists call plexuses. Nerve plexi or nerve plexuses form with the juxtaposition of individual nerve fibers from different spinal cord segments or ganglia. In nerve plexuses, the individual fibers form reticular fiber networks. An extremely fine nerve plexus is located in the human body at the base of the heart. This plexus is called the cardiac plexus or cardiac plexus and lies outside the pericardium. The cardiac plexus is part of the autonomic nervous system. Thus, it is significantly involved in the automatic control of the heart and, as a consequence, in the involuntary control of the blood supply. The superior cardiac cervical nerve represents one of the three sympathetic cardiac nerves and is one of the most important nerves in the cardiac plexus. The plexus consists of a superficial pars superficialis and a much more prominent pars profunda, which lies deep in the tissue. The course of the cardiac plexus follows the course of the coronary artery.

Anatomy and structure

The pars profunda of the cardiac plexus lies posterior to the aortic arch at the bifurcation of the trachea. This part contains cardiac nerve fibers from both sides of the heart. The superficial portion sits below the aortic arch near the right pulmonary artery and carries primarily fibers from the left cardiac nerves. Functionally, the two portions are closely connected. The nerve plexus receives its inflows from sympathetic as well as parasympathetic nerves of the autonomic nervous system. The parasympathetic tributaries include the vagus nerve and the laryngeal recurrent nerve. The sympathetic tributaries correspond to the superior, medius, and inferior cardiac nerve. The cardiac plexus contains several nerve cell nodes of the heart, called ganglia cardiaca. Nerve cell nodes are a collection of nerve cell bodies known technically as ganglia. The largest nerve node of the cardiac plexus is the Wrisberg ganglion with localization in the aortic arch cavity near the ligamentum arteriosum. Connections exist to the thoracic aortic plexus and pulmonary plexus. In addition to motor fibers, pain-conducting fibers and chemoreceptor and pressoreceptor fibers run in the nerve tracts of the cardiac plexus.

Function and Tasks

The cardiac plexus is a part of the autonomic nervous system. Thus, the cardiac plexus is involved in the control of various automatic systems. The processes controlled by the autonomic nervous system escape voluntary influence and can be divided into parasympathetic and sympathetic activities. The cardiac plexus carries nerve fibers of both parts. With parasympathetic and sympathetic fibers, the plexus innervates the heart and thus controls automatic cardiac activity. During stress, for example, the sympathetic nervous system increases the heart’s action via the sympathetic cardiac nerves. In this way, it brings the body into a state of readiness for performance and prepares the organism for greater stress, for which sufficient energy must be available. The parasympathetic nervous system, on the other hand, is associated with relaxation. This part of the autonomic nervous system has a dampening effect on the actions of the sympathetic nervous system and thus establishes a moderate state of rest between complete tension and complete relaxation. Through the sympathetic-prasympathetic interaction, the organism adapts to stress and, from an evolutionary-biological point of view, maintains life even in extreme situations. The cardiac plexus is not the only nerve plexus with sympathetic as well as parasympathetic fibers. Due to its functional tasks in controlling cardiac activity and the cardiovascular system, it is nevertheless one of the most important plexuses in the human body. The control of the heart is mainly performed by the branches in the deep part of the plexus. With these branches, the cardiac plexus particularly influences the heart rate.

Diseases

Arrhythmias are cardiac arrhythmias.In this phenomenon, the heart beats in an irregular sequence. Mild or occasional cardiac arrhythmias often go unnoticed. In the long run, however, irregular heartbeat can cause symptoms such as dizziness, fainting spells, seizures or chest pain. In addition, severe arrhythmias can cause shock. Different forms of arrhythmias are known from clinical practice. Stimulation disorders with disturbed formation of electrical impulses are distinguished from disorders resulting from defective cardiac conduction. Organic causes of accelerated, slowed or stumbling heartbeat may be related to damage of the cardiac plexus. In particular, inflammation of the nervous tissue in this area can result in severe cardiac dysfunction. Psychological cardiac arrhythmias are to be distinguished from this. The cause of such disturbances can be nervousness, excitement or fear. Stress heralds a stressful situation and causes the sympathetic influence on cardiac activity to increase. This shift toward the sympathetic nervous system increases the heart rate. In addition, the heart rate changes with excessive consumption of caffeine and alcohol, as well as with drug, medication, and toxin use. Dysfunctions of the autonomic nervous system can in principle be a symptom of numerous neurological and internal diseases. In this context, systemic degenerations such as Parkinson’s disease or Parkinson’s syndrome are just as relevant as generalized nerve damage in the sense of polyneuropathies, such as can occur as a result of diabetes mellitus. In all cases of functional impairment of the autonomic nervous system, including nerve damage in the cardiac plexus, typical symptoms are dizziness and brief loss of consciousness. The brief periods of unconsciousness are termed syncope.