The muscle tissue of the HEART. It is composed of striated, involuntary muscle cells (MYOCYTES, CARDIAC) connected to form the contractile pump to generate blood flow.

Conical muscular projections from the walls of the cardiac ventricles, attached to the cusps of the atrioventricular valves by the chordae tendineae.

Striated muscle cells found in the heart. They are derived from cardiac myoblasts (MYOBLASTS, CARDIAC). Myoblasts, Cardiac; Myofibrils;

The hollow, muscular organ that maintains the circulation of the blood.

The innermost layer of the heart, comprised of endothelial cells.

The heart of the fetus of any viviparous animal. It refers to the heart in the postembryonic period and is differentiated from the embryonic heart (HEART/embryology) only on the basis of time.

A fetal blood vessel connecting the pulmonary artery with the descending aorta.

The arterial trunk arising from the fetal heart. During development, it divides into AORTA and the PULMONARY ARTERY.

The chambers of the heart, to which the BLOOD returns from the circulation.

Ear-shaped appendage of either atrium of the heart. (Dorland, 28th ed)

An impulse-conducting system composed of modified cardiac muscle and having the power of spontaneous rhythmicity and conduction more highly developed than the rest of the heart.

Modified cardiac muscle fibers composing the terminal portion of the heart conduction system.

Small band of specialized CARDIAC MUSCLE fibers that originates in the ATRIOVENTRICULAR NODE and extends into the membranous part of the interventricular septum. The bundle of His, consisting of the left and the right bundle branches, conducts the electrical impulses to the VENTRICLES in generation of MYOCARDIAL CONTRACTION. Bundle-Branch Block;

A small nodular mass of specialized muscle fibers located in the interatrial septum near the opening of the coronary sinus. It gives rise to the atrioventricular bundle of the conduction system of the heart.

The small mass of modified cardiac muscle fibers located at the junction of the superior vena cava (VENA CAVA, SUPERIOR) and right atrium. Contraction impulses probably start in this node, spread over the atrium (HEART ATRIUM) and are then transmitted by the atrioventricular bundle (BUNDLE OF HIS) to the ventricle (HEART VENTRICLE).

This structure includes the thin muscular atrial septum between the two HEART ATRIA, and the thick muscular ventricular septum between the two HEART VENTRICLES.

An opening in the wall between the right and the left upper chambers (HEART ATRIA) of a fetal heart. Oval foramen normally closes soon after birth; when it fails to close the condition is called PATENT OVALE FORAMEN.

A fetal heart structure that is the bulging areas in the cardiac septum between the HEART ATRIA and the HEART VENTRICLES. During development, growth and fusion of endocardial cushions at midline forms the two atrioventricular canals, the sites for future TRICUSPID VALVE and BICUSPID VALVE.

The thin membrane-like muscular structure separating the right and the left upper chambers (HEART ATRIA) of a heart.

The muscular structure separating the right and the left lower chambers (HEART VENTRICLES) of the heart. The ventricular septum consists of a very small membranous portion just beneath the AORTIC VALVE, and a large thick muscular portion consisting of three sections including the inlet septum, the trabecular septum, and the outlet septum.