Heart valve tricuspid valve has anterior, posterior, and septal cusps; and the mitral valve has just anterior and posterior cusps. The valves of the human heart can be grouped in two sets: 1- Two Atrioventricular (AV) valves to prevent backflow of blood from the ventricles into the atria a) Tricuspid valve, located between the right atrium and right ventricle. b) Bicuspid or mitral valve, located between the left atrium and left ventricle. 2- Two Semilunar valves to prevent the backflow of blood into the ventricle a) Pulmonary semilunar valve, located at the opening between the right ventricle and the pulmonary trunk. b)
Heart that lies over the heart called the cardiac plexus. The vagus nerve is a long, wandering nerve that emerges from the brainstem and provides parasympathetic stimulation to a large number of organs in the thorax and abdomen, including the heart. The nerves from the sympathetic trunk emerge through the T1-T4 thoracic ganglia and travel to both the sinoatrial and atrioventricular nodes, as well as to the atria and ventricles. The ventricles are more richly innervated by sympathetic fibers than parasympathetic fibers. Sympathetic stimulation causes the release of the neurotransmitter norepinephrine (also known as noradrenaline) at the neuromuscular junction of the