!Myocard - Atria and Sinoatrial Node
!!Anatomy
Cardiac muscle is a blend of ((Musculoskeletal - Skeletal Muscles|striated)) and ((Organ Walls - Smooth Muscle Layer|smooth muscle)) in the ((Circulatory - Heart - Overview|heart)), with involuntary innervation by the cardiac plexus. It's ((Circulatory - Blood|blood)) supply is secured by the ((Circulatory - Coronary Arteries (Intima)|coronary arteries)) in a circulation separate from the systemic circulation.
The heart muscle cells are multinuclear, whereas smooth muscle cells are mononuclear. 

{img fileId="228" thumb="box"}

The heart chambers (((Circulatory - Myocardium - Ventricles|ventricles))) are filled from the ((Circulatory - Myocard - Atria|atria)) by coordinated contractions while the ((Circulatory - Endocardium and Heart Valves|valves)) prevent reverse flow. The right ventricle pumps deoxygenated blood via the lung artery into the lungs, whereas the left ventricle supplies the systemic circulation with oxygenated blood. The expulsion is called systole, the filling phase diastole.

{img fileId="226" thumb="box"}graphic: wikipedia

The coordination of contractions in atria and ventricles is effected by an autonomous center of excitation and conduction which is influenced by the autonomous nervous system and by hormones. 
The __sinoatrial node__ (SA-node) is situated in the right atrium nearby the junction of the superior caval vein. It consists of specialized muscle cells capable of spontaneous depolarization, which can excite autonomously and thereby generate the rhythm of contractions. The sympathetic nervous system and ((Endocrine - Adrenal Gland - Medulla|adrenal medulla)) hormones speed up the sinus rhythm, the vagus can inhibit it (__vagus brake__). Conduction and coordination with the ventricles is carried out via the atrio-ventricular node (AV-node) which is influenced by the relays of the ((Circulatory - Coronary Arteries (Intima)|coronary arteries)) (slow rhythm) and ((Circulatory - Coronary Veins (intima)|coronary veins)) (fast rhythm).

{img fileId="230" thumb="box"} Conduction 1:Sinoatrial node 2. Atrioventricular node
graphic: wikipedia, Patrick J Lynch

The myocardium of atria and ((Circulatory - Myocardium - Ventricles|ventricles)) show different reaction patterns and conflict themes. The atrial myocardium has a relay in the midbrain, the ventricular myocardium in the cerebral medulla. 

!!Brain
{img fileId="202" thumb="box"}

{img fileId="227" thumb="box"} Cut through the midbrain at the level of inferior colliculus
graphic: wikipedia, Kevin Dufendach

Relay:
__Midbrain/Plexus Cardiacus__ ( + / - ), frontolateral left & right
compare __Brain Stem__ {img fileId="190" thumb="box"} brain-organ relation crossed!

!!Mind
!!!Theme
Overwhelm (not being able to secure survival/ the blood flow in the heart)

!!!Emotions, Thoughts
__Anxiety__ often because of other heart problems.

!!!META-Meaning
My heart works easily and faithfully. Everything goes like a dance!

!!Organ
In embryonic development, the heart has made a turn so that curiously, brain stem innervation crosses over. The sinus node, innervated by fibres from the left plexus cardiacus, stimulates the right atrium and the right ventricle.

!!!Stress Phase Symptoms
__Forced rhythm__ through the sinus node, contractility of cardiac muscle, especially in the atria. The atrial wall __thickens__.

!!!Regeneration Phase Symptoms
Tonus normalization of cardiac muscle especially in the atrium, often accompanied by __vagotonic tachycardia__ (fibrillation), while thickening of the muscle remains.

!!!Healing Peak
Atrial tachycardia, __atrial fibrillation__ or atrial flutter, accompanied by restlessness, but no myocardial infarction!

!!!Biological Meaning
Support of the cardiac muscle during stress reaction is like a “double safety”. Another meaning is the increase in strength which lasts after regeneration.

!!Social
!!!Examples
*Due to a connective tissue disease, patient had dilated aorta and dilated heart chambers. Since it has been operated, he is constantly worrying about heart problems, measuring his pulse and listening to his own heart beat to check if it’s still beating normally. Thereby, he develops atrial tachycardia and partial atrial fibrillation.
*Patient’s mother has died from heart attack. Since then, she has been constantly worrying about having a heart disease. Thereby, she develops atrial tachycdia, accompanied by an unpleasant feeling in heart area.

!!Additional Information
!!!Differential Diagnosis
__((Circulatory - Coronary Arteries (Intima)|Coronary Arteries and AV node))__ (Cerebral Cortex, Plexus Cardiacus, -/+) with heart arrythmia and angina pectoris in the stress phase (loss of love/status); and bradycardia, possibly heart arrest, absence, heart pain in the healing peak

__((Circulatory - Coronary Veins (intima)|Coronary Veins)) __(Cerebral Cortex, Plexus Cardiacus, -/+) with painful angina pectoris in the stress phase (loss of love/status); and absence, tachycardia or ventricular fibrillation in the regeneration phase

__((Circulatory - Endocardium and Heart Valves|Endocardium))__ (Cerebral Medulla, Plexus Cardiacus, -/+) with reduced heart performance due to valve insufficiency in stress phase (performance self-devaluation), painful endocarditis in regeneration phase

__((Circulatory - Myocardium - Ventricles|Myocardium/Ventricular))__ (Cerebral Medulla, Plexus Cardiacus, -/+) with reduced heart performance due to local paralysis in the stress phase (overwhelm), myocardium infarction in healing peak

__((Circulatory - Pericardium and Epicardium|Pericardium))__ (Cerebellum, Plexus Cardiacus, +/-) with feeling of pressure or “armored heart” in stress phase (protection of the heart), cardiac insufficiency due to effusion in regeneration phase
