Right atrium and ventricle
After going through this study unit you will be able to:
- Identify the chambers of the heart.
- Understand the function of the right atrium and ventricle and their relations.
- Describe and name the structures of the right heart.
The right atrium occupies the upper right side of the heart above the right ventricle. It is the first chamber of the heart to receive the deoxygenated blood from the body via 3 main sources. That includes the superior vena cava, which drains blood from the upper parts of the body, the inferior vena cava, which collects blood from the lower parts, and the coronary sinus, which drains blood from the heart itself. One of the main features of the right atrium is the sinoatrial (SA) node that is placed within the wall of this chamber adjacent to the entrance of the superior vena cava. It is known as “the human pacemaker” that spontaneously generates electrical impulses and determines the normal heart rhythm.
The right ventricle takes up the majority of the anterior surface of the heart. It receives blood from the right atrium and pumps it via the pulmonary trunk into the lungs for blood oxygenation. The blood flow between these heart chambers is regulated by the right atrioventricular (tricuspid) valve, allowing only unidirectional flow from the right atrium to the right ventricle. Similarly, the pulmonary valve permits the blood to flow from the right ventricle to the pulmonary trunk without regurgitation.
Watch the following video and learn everything you should know about the right atrium and ventricle, their functions and anatomical relations:
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Take a closer look at the structures of the right atrium and ventricle in the atlas gallery below.
|Features||Receives deoxygenated blood from the systemic circulation via the superior vena cava, inferior vena cava and coronary sinus
Characteristics: Thin wall; contains the sinoatrial and atrioventricular nodes; three internal surfaces (venous, vestibular, auricular)
Landmarks: Right auricle
Function: Reservoir for blood and an active pump that helps fill the ventricle
|Right auricle of heart||Cone-shaped pouch which extends from the superoanterior part of right atrium|
|Pectinate muscles||Array of parallel muscular columns on the internal anterior wall of right atrium|
|Crista terminalis||Crescent-shaped muscular ridge on the internal aspect of right atrium that externally corresponds with the terminal sulcus|
|Sinus of venae cavae||Portion of right atrium that receives the superior and inferior venae cavae|
|Vestibule of right atrioventricular valve||Fibrous rings that support the leaflets of the right atrioventricular valve|
|Fossa ovalis||Oval depression on the interatrial septum (remnant of foramen ovale)|
|Sinoatrial (SA) node
|Collection of specialized nodal tissue that produces electrical impulses that travel through the electrical conduction system|
|Atrioventricular (AV) node||Part of electrical conduction system found near coronary sinus on the interatrial septum|
|Features||Receives deoxygenated blood from the right atrium and pumps it to the lungs for oxygenation
Characteristics: Septomarginal trabecula (moderator band)
Landmarks: Three prominent papillary muscles
Function: Pumps blood into the pulmonary circulation
|Supraventricular crest||Round accentuation of the internal muscular wall that separates the conus arteriosus from the rest of the ventricular cavity|
|Conus arteriosus||Conical pouch where the pulmonary trunk arises|
|Trabeculae carneae||Muscular elevations that course along mainly apical parts of ventricular wall|
|Papillary muscles (anterior, inferior, septal), chordae tendineae||Muscular projections attached to cusps of right atrioventricular valve via tendinous cords (chordae tendineae) preventing prolapse|
|Septomarginal trabecula||A muscular tissue that transmits the right branch of atrioventricular bundle from the interventricular septum to the anterior papillary muscle|